"Jeffrey Angus" wrote in message
...
On 6/21/2011 7:25 AM, William Sommerwerck wrote:
"Jeffrey wrote in message
...
On 6/20/2011 10:36 PM, William Sommerwerck wrote:

Why don't you stop by, and I'll pull out the heating element part way.
Then you can touch one of the wires feeding the element with one hand,
and the a ground (such as the oven cabinet) with your other other
hand.

Care to bet your life on it?

I'd be happy to, idiot. I have enough sense to disconnect it first.

Oh. I thought all that was needed was to disconnect one side.

Uh huh, you're purposely talking in circles here....

You only have to disconnect one side to make the heater not heat.
You have to disconnect BOTH sides to make sure it's doesn't have
power on it to safely service the unit.

Of course. That's why I wondered why you were saying what you did -- since
the whole point of my original plaint was that only one side was disconected
from the line.

My toaster oven doesn't shut off when you open the door, either because
B&D
was cheap, or the designer didn't think anything bad would ever happen.
Older models did, including ones with sealed heating elements.


Does your gas oven shut it self off when you open the door?

Good question. I've never owned a gas oven, so I don't know. However, a gas
oven offers only the possibility of burning one's self -- not electrocution.
And for a number of obvious reasons, you wouldn't want to shut it off that
way, anyway.


What kind of red herring is this? It's a ****ing toaster oven, not
a front loading washing machine.

It's not a red herring. It's that toaster ovens /used/ to be designed to
fully shut off the power when the door was opened, even though the chance of
users electrocuting themselves was less than minuscule. I don't see why this
shouldn't apply to ovens.

On 21/06/2011 12:11 PM, Jeffrey Angus wrote:
On 6/20/2011 7:16 PM, William Sommerwerck wrote:
Remember, it ONLY takes ONE switch to OPEN a series circuit.
That is ALL that is required to control whether or not the
element gets hot or cools off.

You were not paying attention! Any heating device that uses both "phases"
requres TWO switches to open it.


Oh, and by the way, since you brought it up, the bit about
both of the 240 volt sources being "hot with respect to
neutral". The heating elements are connected ACROSS the 240
VAC source, NOT split with each half going from the two
sources to neutral. (That would require a double contact to
turn each PAIR of heating elements on and off.)

I'm not sure what you're talking about. First, there is no "240V"
source in
my condo. There are multiple 120V sources from which you can get higher
voltages by spanning them. (I assume each voltage is referenced to some
"neutral" point.) In my preceding apartment, I took advantage of this to
build a break-out box -- all to code, I have several electrician
friends who
advised me -- to provide individual lines for my class A power amps.

As someone else kindly pointed out, this oven has one side of its
elements
hard-wired to AC. Bad, bad, bad, bad idea.

Damn you are ****ing dense William.

The heating element from one hot lead to the other hot lead.
At NO time is there a connection to Neutral. Hence it ONLY
requires a SINGLE pole switch to open a SERIES circuit.

I see no inconsistency. A correctly functioning heating element can be
turned off, in the sense of no longer heating, by means of a single pole
switch.

But what about a non-correctly functioning heating element? One, for
example, that's shorted to its grounded covering somewhere along its
length. This could result in part of the element overheating, and an
owner noticing this would likely respond by turning the appliance off at
its switch. In the case of a heating element that spans two 110 v lines
in opposite phase, turning it off by a single pole switch won't have the
desired effect. Better hope that an earth leakage detector is fitted in
the supply lines, and works.

Sylvia.

Sylvia Else wrote:

On 21/06/2011 12:11 PM, Jeffrey Angus wrote:
On 6/20/2011 7:16 PM, William Sommerwerck wrote:
Remember, it ONLY takes ONE switch to OPEN a series circuit.
That is ALL that is required to control whether or not the
element gets hot or cools off.

You were not paying attention! Any heating device that uses both "phases"
requres TWO switches to open it.


Oh, and by the way, since you brought it up, the bit about
both of the 240 volt sources being "hot with respect to
neutral". The heating elements are connected ACROSS the 240
VAC source, NOT split with each half going from the two
sources to neutral. (That would require a double contact to
turn each PAIR of heating elements on and off.)

I'm not sure what you're talking about. First, there is no "240V"
source in
my condo. There are multiple 120V sources from which you can get higher
voltages by spanning them. (I assume each voltage is referenced to some
"neutral" point.) In my preceding apartment, I took advantage of this to
build a break-out box -- all to code, I have several electrician
friends who
advised me -- to provide individual lines for my class A power amps.

As someone else kindly pointed out, this oven has one side of its
elements
hard-wired to AC. Bad, bad, bad, bad idea.

Damn you are ****ing dense William.

The heating element from one hot lead to the other hot lead.
At NO time is there a connection to Neutral. Hence it ONLY
requires a SINGLE pole switch to open a SERIES circuit.

I see no inconsistency. A correctly functioning heating element can be
turned off, in the sense of no longer heating, by means of a single pole
switch.

But what about a non-correctly functioning heating element? One, for
example, that's shorted to its grounded covering somewhere along its
length. This could result in part of the element overheating, and an
owner noticing this would likely respond by turning the appliance off at
its switch. In the case of a heating element that spans two 110 v lines
in opposite phase, turning it off by a single pole switch won't have the
desired effect. Better hope that an earth leakage detector is fitted in
the supply lines, and works.


That's what the 2 pole fuse/circuit breaker is for.

Sylvia.


--
It's easy to think outside the box, when you have a cutting torch.

On Thu, 23 Jun 2011 12:27:06 +1000, Sylvia Else
wrote:

On 21/06/2011 12:11 PM, Jeffrey Angus wrote:
On 6/20/2011 7:16 PM, William Sommerwerck wrote:
Remember, it ONLY takes ONE switch to OPEN a series circuit.
That is ALL that is required to control whether or not the
element gets hot or cools off.

You were not paying attention! Any heating device that uses both "phases"
requres TWO switches to open it.


Oh, and by the way, since you brought it up, the bit about
both of the 240 volt sources being "hot with respect to
neutral". The heating elements are connected ACROSS the 240
VAC source, NOT split with each half going from the two
sources to neutral. (That would require a double contact to
turn each PAIR of heating elements on and off.)

I'm not sure what you're talking about. First, there is no "240V"
source in
my condo. There are multiple 120V sources from which you can get higher
voltages by spanning them. (I assume each voltage is referenced to some
"neutral" point.) In my preceding apartment, I took advantage of this to
build a break-out box -- all to code, I have several electrician
friends who
advised me -- to provide individual lines for my class A power amps.

As someone else kindly pointed out, this oven has one side of its
elements
hard-wired to AC. Bad, bad, bad, bad idea.

Damn you are ****ing dense William.

The heating element from one hot lead to the other hot lead.
At NO time is there a connection to Neutral. Hence it ONLY
requires a SINGLE pole switch to open a SERIES circuit.

I see no inconsistency. A correctly functioning heating element can be
turned off, in the sense of no longer heating, by means of a single pole
switch.

But what about a non-correctly functioning heating element? One, for
example, that's shorted to its grounded covering somewhere along its
length. This could result in part of the element overheating, and an
owner noticing this would likely respond by turning the appliance off at
its switch. In the case of a heating element that spans two 110 v lines
in opposite phase, turning it off by a single pole switch won't have the
desired effect. Better hope that an earth leakage detector is fitted in
the supply lines, and works.

Sylvia.
I had exactly this happen over a decade ago. The center resistance
element started arcing to the outer sheath. This action was clearly
visible. When turning off the oven didn't help, I did what any
intelligent person should do - I turned off the circuit breaker.

I repeat - only a fool works on electrical equipment without making
sure it has been disconnected from power. 'Assuming' that both sides
of the power line are switched is stupid. Beleiving that the circuit
breaker is correctly labeled is foolish. Trusting the circuit breaker
is working correctly is only slightly less so.

About 5 years ago a lady named Gina Marie Wylie published an online
serial called 'Spitfire and Messerschmidt'. In the story, an Air
Conditioning serviceman is called upon to determine why the central
air conditioner has stopped. In exquisite detail it is described how
he checked the thermostat, then turned off the circuit breaker, pulled
the access panel, then used a voltmeter to verify the power was off.
When Davey (AKA Messerschmidt) questions this, the serviceman explains
"I have a six year old son. I look forward to going home and playing
with him tonight. I don't want someone to have to explain to him that
Daddy was in a hurry, made a mistake, and won't ever be coming home."

I'm sure the OP's significant other would not be comforted by the
epitath 'I thought it was turned off.'

PlainBill

In article ,
wrote:

I'm sure the OP's significant other would not be comforted by the
epitath 'I thought it was turned off.'

Well said.

I understand that if you look at the statistics on people who suffer
injuries while working with (e.g.) power woodworking tools such as
table saws and lathes, you find:

- A significant but moderate percentage of "newbies" who didn't
read the instructions and warnings, and thus "didn't know better",

and

- A rather higher percentage of people with quite a lot of experience
with the equipment, who (when asked about it afterwards) say
something like "Yeah, I knew better, I knew I was taking a shortcut
and ignoring Precaution X".

As they say, "Familiarity breeds contempt" - in this case, familiarity
with the equipment or working environment tends to breed contempt for
safety precautions. "I got away with that before..."

--
Dave Platt AE6EO
Friends of Jade Warrior home page: http://www.radagast.org/jade-warrior
I do _not_ wish to receive unsolicited commercial email, and I will
boycott any company which has the gall to send me such ads!

On 24/06/2011 8:22 AM, Michael A. Terrell wrote:

Sylvia Else wrote:

On 21/06/2011 12:11 PM, Jeffrey Angus wrote:
On 6/20/2011 7:16 PM, William Sommerwerck wrote:
Remember, it ONLY takes ONE switch to OPEN a series circuit.
That is ALL that is required to control whether or not the
element gets hot or cools off.

You were not paying attention! Any heating device that uses both "phases"
requres TWO switches to open it.


Oh, and by the way, since you brought it up, the bit about
both of the 240 volt sources being "hot with respect to
neutral". The heating elements are connected ACROSS the 240
VAC source, NOT split with each half going from the two
sources to neutral. (That would require a double contact to
turn each PAIR of heating elements on and off.)

I'm not sure what you're talking about. First, there is no "240V"
source in
my condo. There are multiple 120V sources from which you can get higher
voltages by spanning them. (I assume each voltage is referenced to some
"neutral" point.) In my preceding apartment, I took advantage of this to
build a break-out box -- all to code, I have several electrician
friends who
advised me -- to provide individual lines for my class A power amps.

As someone else kindly pointed out, this oven has one side of its
elements
hard-wired to AC. Bad, bad, bad, bad idea.

Damn you are ****ing dense William.

The heating element from one hot lead to the other hot lead.
At NO time is there a connection to Neutral. Hence it ONLY
requires a SINGLE pole switch to open a SERIES circuit.

I see no inconsistency. A correctly functioning heating element can be
turned off, in the sense of no longer heating, by means of a single pole
switch.

But what about a non-correctly functioning heating element? One, for
example, that's shorted to its grounded covering somewhere along its
length. This could result in part of the element overheating, and an
owner noticing this would likely respond by turning the appliance off at
its switch. In the case of a heating element that spans two 110 v lines
in opposite phase, turning it off by a single pole switch won't have the
desired effect. Better hope that an earth leakage detector is fitted in
the supply lines, and works.


That's what the 2 pole fuse/circuit breaker is for.

It takes time to reach it, and that time may not be available.

Sylvia.

On 24/06/2011 8:53 AM, wrote:
On Thu, 23 Jun 2011 12:27:06 +1000, Sylvia Else
wrote:

On 21/06/2011 12:11 PM, Jeffrey Angus wrote:
On 6/20/2011 7:16 PM, William Sommerwerck wrote:
Remember, it ONLY takes ONE switch to OPEN a series circuit.
That is ALL that is required to control whether or not the
element gets hot or cools off.

You were not paying attention! Any heating device that uses both "phases"
requres TWO switches to open it.


Oh, and by the way, since you brought it up, the bit about
both of the 240 volt sources being "hot with respect to
neutral". The heating elements are connected ACROSS the 240
VAC source, NOT split with each half going from the two
sources to neutral. (That would require a double contact to
turn each PAIR of heating elements on and off.)

I'm not sure what you're talking about. First, there is no "240V"
source in
my condo. There are multiple 120V sources from which you can get higher
voltages by spanning them. (I assume each voltage is referenced to some
"neutral" point.) In my preceding apartment, I took advantage of this to
build a break-out box -- all to code, I have several electrician
friends who
advised me -- to provide individual lines for my class A power amps.

As someone else kindly pointed out, this oven has one side of its
elements
hard-wired to AC. Bad, bad, bad, bad idea.

Damn you are ****ing dense William.

The heating element from one hot lead to the other hot lead.
At NO time is there a connection to Neutral. Hence it ONLY
requires a SINGLE pole switch to open a SERIES circuit.

I see no inconsistency. A correctly functioning heating element can be
turned off, in the sense of no longer heating, by means of a single pole
switch.

But what about a non-correctly functioning heating element? One, for
example, that's shorted to its grounded covering somewhere along its
length. This could result in part of the element overheating, and an
owner noticing this would likely respond by turning the appliance off at
its switch. In the case of a heating element that spans two 110 v lines
in opposite phase, turning it off by a single pole switch won't have the
desired effect. Better hope that an earth leakage detector is fitted in
the supply lines, and works.

Sylvia.
I had exactly this happen over a decade ago. The center resistance
element started arcing to the outer sheath. This action was clearly
visible. When turning off the oven didn't help, I did what any
intelligent person should do - I turned off the circuit breaker.


I'm not so convinced that people who aren't used to fiddling with the
breaker box would immediately think of that in the heat (?) of the
moment. IMHO the switch on an appliance should disconnect the power, at
least if the appliance and supply are correctly wired. If the appliance
uses live and neutral, then a single pole switch is sufficient, but if
it uses two live wires, it should have a double pole switch.

Leaving aside the fault that occurs while an appliance is in use, if
parts of the appliance are live when the appliance is turned off, then
it can still go up in flames if a fault develops within. This was not
such an infrequenty occurence in the UK when TVs weren't earthed and had
unpolarised power cords which could result in the chassis (!) being
live, even when the TV was turned off.

Sylvia.

Sylvia Else wrote:

On 24/06/2011 8:22 AM, Michael A. Terrell wrote:

Sylvia Else wrote:

On 21/06/2011 12:11 PM, Jeffrey Angus wrote:
On 6/20/2011 7:16 PM, William Sommerwerck wrote:
Remember, it ONLY takes ONE switch to OPEN a series circuit.
That is ALL that is required to control whether or not the
element gets hot or cools off.

You were not paying attention! Any heating device that uses both "phases"
requres TWO switches to open it.


Oh, and by the way, since you brought it up, the bit about
both of the 240 volt sources being "hot with respect to
neutral". The heating elements are connected ACROSS the 240
VAC source, NOT split with each half going from the two
sources to neutral. (That would require a double contact to
turn each PAIR of heating elements on and off.)

I'm not sure what you're talking about. First, there is no "240V"
source in
my condo. There are multiple 120V sources from which you can get higher
voltages by spanning them. (I assume each voltage is referenced to some
"neutral" point.) In my preceding apartment, I took advantage of this to
build a break-out box -- all to code, I have several electrician
friends who
advised me -- to provide individual lines for my class A power amps.

As someone else kindly pointed out, this oven has one side of its
elements
hard-wired to AC. Bad, bad, bad, bad idea.

Damn you are ****ing dense William.

The heating element from one hot lead to the other hot lead.
At NO time is there a connection to Neutral. Hence it ONLY
requires a SINGLE pole switch to open a SERIES circuit.

I see no inconsistency. A correctly functioning heating element can be
turned off, in the sense of no longer heating, by means of a single pole
switch.

But what about a non-correctly functioning heating element? One, for
example, that's shorted to its grounded covering somewhere along its
length. This could result in part of the element overheating, and an
owner noticing this would likely respond by turning the appliance off at
its switch. In the case of a heating element that spans two 110 v lines
in opposite phase, turning it off by a single pole switch won't have the
desired effect. Better hope that an earth leakage detector is fitted in
the supply lines, and works.


That's what the 2 pole fuse/circuit breaker is for.

It takes time to reach it, and that time may not be available.


The element is inside a metal oven. How long do you think it will
take for the defctive element to burn a hole in it? How long before the
breaker would trip or the fuse would open on their own?


--
It's easy to think outside the box, when you have a cutting torch.

On 24/06/2011 7:20 PM, Michael A. Terrell wrote:

Sylvia Else wrote:

On 24/06/2011 8:22 AM, Michael A. Terrell wrote:

Sylvia Else wrote:

On 21/06/2011 12:11 PM, Jeffrey Angus wrote:
On 6/20/2011 7:16 PM, William Sommerwerck wrote:
Remember, it ONLY takes ONE switch to OPEN a series circuit.
That is ALL that is required to control whether or not the
element gets hot or cools off.

You were not paying attention! Any heating device that uses both "phases"
requres TWO switches to open it.


Oh, and by the way, since you brought it up, the bit about
both of the 240 volt sources being "hot with respect to
neutral". The heating elements are connected ACROSS the 240
VAC source, NOT split with each half going from the two
sources to neutral. (That would require a double contact to
turn each PAIR of heating elements on and off.)

I'm not sure what you're talking about. First, there is no "240V"
source in
my condo. There are multiple 120V sources from which you can get higher
voltages by spanning them. (I assume each voltage is referenced to some
"neutral" point.) In my preceding apartment, I took advantage of this to
build a break-out box -- all to code, I have several electrician
friends who
advised me -- to provide individual lines for my class A power amps.

As someone else kindly pointed out, this oven has one side of its
elements
hard-wired to AC. Bad, bad, bad, bad idea.

Damn you are ****ing dense William.

The heating element from one hot lead to the other hot lead.
At NO time is there a connection to Neutral. Hence it ONLY
requires a SINGLE pole switch to open a SERIES circuit.

I see no inconsistency. A correctly functioning heating element can be
turned off, in the sense of no longer heating, by means of a single pole
switch.

But what about a non-correctly functioning heating element? One, for
example, that's shorted to its grounded covering somewhere along its
length. This could result in part of the element overheating, and an
owner noticing this would likely respond by turning the appliance off at
its switch. In the case of a heating element that spans two 110 v lines
in opposite phase, turning it off by a single pole switch won't have the
desired effect. Better hope that an earth leakage detector is fitted in
the supply lines, and works.


That's what the 2 pole fuse/circuit breaker is for.

It takes time to reach it, and that time may not be available.


The element is inside a metal oven. How long do you think it will
take for the defctive element to burn a hole in it? How long before the
breaker would trip or the fuse would open on their own?


How long was the problem festering before the user noticed?

If it doesn't matter how long it takes for the user to reach the circuit
breaker, then it doesn't matter if they don't bother.

An ELT would trip straight away, if one's fitted, which it might not be
in this kind of circuit. There's no guarantee that there'd ever be an
overcurrent trip.

Sylvia.

Sylvia Else wrote:

Michael A. Terrell wrote:

Sylvia Else wrote:

Michael A. Terrell wrote:

The element is inside a metal oven. How long do you think it will
take for the defctive element to burn a hole in it? How long before the
breaker would trip or the fuse would open on their own?

How long was the problem festering before the user noticed?


Festering? Get real. We aren't talking low temperature an a few mA.


If it doesn't matter how long it takes for the user to reach the circuit
breaker, then it doesn't matter if they don't bother.

An ELT would trip straight away, if one's fitted, which it might not be
in this kind of circuit. There's no guarantee that there'd ever be an
overcurrent trip.

Emergency Locator Transmitter?
Extremely Large Telescope?

These are the only uses of 'ELT' I've seen in the United States. It
is where I live, and so does the OP.


Sigh. Think it through. The body of the oven is grounded. If a
calrod element is failing, it isn't gradual. If it shorts to the metal
body the fuse blows, or the breaker trips since it is less than a full
load resistance.

If the element opens inside the metal tube, it generally creates
plasma which burns through the casing and opens the element
permanently. Even a bad connector will self destruct at those currents.
There is an exceedingly small chance for an intermittent element.


--
It's easy to think outside the box, when you have a cutting torch.

"Sylvia Else" wrote in message
...
On 24/06/2011 8:53 AM, wrote:
On Thu, 23 Jun 2011 12:27:06 +1000, Sylvia Else
wrote:

On 21/06/2011 12:11 PM, Jeffrey Angus wrote:
On 6/20/2011 7:16 PM, William Sommerwerck wrote:
Remember, it ONLY takes ONE switch to OPEN a series circuit.
That is ALL that is required to control whether or not the
element gets hot or cools off.

You were not paying attention! Any heating device that uses both
"phases"
requres TWO switches to open it.


Oh, and by the way, since you brought it up, the bit about
both of the 240 volt sources being "hot with respect to
neutral". The heating elements are connected ACROSS the 240
VAC source, NOT split with each half going from the two
sources to neutral. (That would require a double contact to
turn each PAIR of heating elements on and off.)

I'm not sure what you're talking about. First, there is no "240V"
source in
my condo. There are multiple 120V sources from which you can get
higher
voltages by spanning them. (I assume each voltage is referenced to
some
"neutral" point.) In my preceding apartment, I took advantage of this
to
build a break-out box -- all to code, I have several electrician
friends who
advised me -- to provide individual lines for my class A power amps.

As someone else kindly pointed out, this oven has one side of its
elements
hard-wired to AC. Bad, bad, bad, bad idea.

Damn you are ****ing dense William.

The heating element from one hot lead to the other hot lead.
At NO time is there a connection to Neutral. Hence it ONLY
requires a SINGLE pole switch to open a SERIES circuit.

I see no inconsistency. A correctly functioning heating element can be
turned off, in the sense of no longer heating, by means of a single pole
switch.

But what about a non-correctly functioning heating element? One, for
example, that's shorted to its grounded covering somewhere along its
length. This could result in part of the element overheating, and an
owner noticing this would likely respond by turning the appliance off at
its switch. In the case of a heating element that spans two 110 v lines
in opposite phase, turning it off by a single pole switch won't have the
desired effect. Better hope that an earth leakage detector is fitted in
the supply lines, and works.

Sylvia.
I had exactly this happen over a decade ago. The center resistance
element started arcing to the outer sheath. This action was clearly
visible. When turning off the oven didn't help, I did what any
intelligent person should do - I turned off the circuit breaker.


I'm not so convinced that people who aren't used to fiddling with the
breaker box would immediately think of that in the heat (?) of the moment.
IMHO the switch on an appliance should disconnect the power, at least if
the appliance and supply are correctly wired. If the appliance uses live
and neutral, then a single pole switch is sufficient, but if it uses two
live wires, it should have a double pole switch.

Leaving aside the fault that occurs while an appliance is in use, if parts
of the appliance are live when the appliance is turned off, then it can
still go up in flames if a fault develops within. This was not such an
infrequenty occurence in the UK when TVs weren't earthed and had
unpolarised power cords which could result in the chassis (!) being live,
even when the TV was turned off.

Sylvia.

In all the years that I was directly involved with with TV sets in the UK,
working for one of the big four rental companies, I can only ever remember
one TV "going up in flames". It most certainly was not a common or frequent
occurrence. Further, I don't think I can recall any commonly sold make or
model, which ever employed an earth connection to the chassis. As for power
cords not being polarised, it depends exactly what you mean by that. In the
very early days, there were some sets that used a two pin plug-in power lead
which could be reversed. Likewise, there were two pin power sockets which
again could have the plugs for them reversed. However, by the time TV was
firmly established in the UK as an 'in every home' item, these sets were
long gone, and fixed power leads with colour-polarised wires, were the norm.
When we went over to the 13 A three pin wall socket convention, then as long
as the plug had been wired correctly, a 'live chassis' TV could never
actually have its chassis connected to the 'live' side of the incoming line
power. As to the chassis being live " even when the TV was turned off ", the
vast majority of sets that I saw employed a two pole power switch, ganged to
the volume control, so when they were switched off, both the line and the
neutral wires were disconnected from the TV.

On the cooker isolation issue, here in the UK, electric cookers are
typically connected via a permanently wired power cord that goes to a custom
outlet plate specifically designed and sold for the purpose. It is usual for
that outlet plate to be well down the wall behind the cooker, but connected
inside the wall to a further 'panel' mounted above counter height. On this
panel is either a large red switch on its own, or a large red switch, and a
three pin conventional power outlet. This is the double pole isolation
switch for the cooker, and is in addition to the fuse and breaker covering
this (independent) circuit, back at the fuse board.

http://www.pvrdirect.co.uk/productin...tref=SMJW45CUC

Arfa

On Fri, 24 Jun 2011 11:07:08 +1000, Sylvia Else
wrote:

On 24/06/2011 8:53 AM, wrote:
On Thu, 23 Jun 2011 12:27:06 +1000, Sylvia Else
wrote:

On 21/06/2011 12:11 PM, Jeffrey Angus wrote:
On 6/20/2011 7:16 PM, William Sommerwerck wrote:
Remember, it ONLY takes ONE switch to OPEN a series circuit.
That is ALL that is required to control whether or not the
element gets hot or cools off.

You were not paying attention! Any heating device that uses both "phases"
requres TWO switches to open it.


Oh, and by the way, since you brought it up, the bit about
both of the 240 volt sources being "hot with respect to
neutral". The heating elements are connected ACROSS the 240
VAC source, NOT split with each half going from the two
sources to neutral. (That would require a double contact to
turn each PAIR of heating elements on and off.)

I'm not sure what you're talking about. First, there is no "240V"
source in
my condo. There are multiple 120V sources from which you can get higher
voltages by spanning them. (I assume each voltage is referenced to some
"neutral" point.) In my preceding apartment, I took advantage of this to
build a break-out box -- all to code, I have several electrician
friends who
advised me -- to provide individual lines for my class A power amps.

As someone else kindly pointed out, this oven has one side of its
elements
hard-wired to AC. Bad, bad, bad, bad idea.

Damn you are ****ing dense William.

The heating element from one hot lead to the other hot lead.
At NO time is there a connection to Neutral. Hence it ONLY
requires a SINGLE pole switch to open a SERIES circuit.

I see no inconsistency. A correctly functioning heating element can be
turned off, in the sense of no longer heating, by means of a single pole
switch.

But what about a non-correctly functioning heating element? One, for
example, that's shorted to its grounded covering somewhere along its
length. This could result in part of the element overheating, and an
owner noticing this would likely respond by turning the appliance off at
its switch. In the case of a heating element that spans two 110 v lines
in opposite phase, turning it off by a single pole switch won't have the
desired effect. Better hope that an earth leakage detector is fitted in
the supply lines, and works.

Sylvia.
I had exactly this happen over a decade ago. The center resistance
element started arcing to the outer sheath. This action was clearly
visible. When turning off the oven didn't help, I did what any
intelligent person should do - I turned off the circuit breaker.


I'm not so convinced that people who aren't used to fiddling with the
breaker box would immediately think of that in the heat (?) of the
moment. IMHO the switch on an appliance should disconnect the power, at
least if the appliance and supply are correctly wired. If the appliance
uses live and neutral, then a single pole switch is sufficient, but if
it uses two live wires, it should have a double pole switch.

Leaving aside the fault that occurs while an appliance is in use, if
parts of the appliance are live when the appliance is turned off, then
it can still go up in flames if a fault develops within. This was not
such an infrequenty occurence in the UK when TVs weren't earthed and had
unpolarised power cords which could result in the chassis (!) being
live, even when the TV was turned off.

Sylvia.

Let's take a look at what will happen if the heating element fails by
shorting from the resistance element to the sheath. I will assume
that the failure I observed is worst case - an actual arc formed.
This gradually (1-2" per minute) moved toward the end of the heating
element. As the length of the resistance element got shorter, the
current would rise. Eventually the circuit breaker would trip. The
chance of a fire was very small. Most modern kitchen ranges have self
cleaning ovens which clean by heating themselves up high enough the
grease and spills are oxidized.

As I stated before, the problem was not in the design. Granted,
William Sommerwerk would not have received a shock if both lines were
interuurpted. However, that's not absolute protection. Switch and
relay contacts do weld together, triacs do short. One particular
brand of circuit breaker has been banned because the contacts tend to
weld together.

The chain of events is simple - The range was designed to meet certain
standards. William Sommerwerk assumed it was designed to his
standards. What is more, he was so confident in his assumption, he
failed to take the most emementary precaution of actually testing that
the terminal was not live.

Perhaps some may feel I am paranoid, but I have observed enough cases
where things were not as they should have been that I don't trust
labels, nor do I trust circuit breakers. Heck, I don't even trust a
simple neon bulb tester unless I check it!!

I've seen licensed electricians swap live and neutral wires in an
outlet box. I've seen a breaker box where the position labeled
'range' actually held two 15 amp breakers. I've seen a 12 gauge
(rated for 20 Amps) wire hooked to a 45 amp circuit breaker. I've
seen 'TN' wires (for installation in a conduit) strung across an attic
to power a ceiling fan in the room below.

PlainBill

Circuit breakers don't need to be explained.

In probably less than 1/1000 of installations in any relatively modern home,
there is a power plug (on a short cord) and receptacle for a kitchen range..
it's a service disconnect.

Disconnects are defined and required by codes in many places, certainly by
the NEC, and just plain (un?)-common sense.

--
Cheers,
WB
..............


"William Sommerwerck" wrote in message
...
I just had to replace the bottom element in my GE oven, and discovered --
to
my great surprise -- that one side of the element is always "hot" -- that
is, it has voltage on it. I will be calling Appliance Park next week and
verbally tearing someone a new oven cavity.

Is this normal? And if it is, is it for some reason other than saving
money?

--
"We already know the answers -- we just haven't asked the right
questions." -- Edwin Land

On Jun 23, 6:53*pm, wrote:
On Thu, 23 Jun 2011 12:27:06 +1000, Sylvia Else



wrote:
On 21/06/2011 12:11 PM, Jeffrey Angus wrote:
On 6/20/2011 7:16 PM, William Sommerwerck wrote:
Remember, it ONLY takes ONE switch to OPEN a series circuit.
That is ALL that is required to control whether or not the
element gets hot or cools off.

You were not paying attention! Any heating device that uses both "phases"
requres TWO switches to open it.

Oh, and by the way, since you brought it up, the bit about
both of the 240 volt sources being "hot with respect to
neutral". The heating elements are connected ACROSS the 240
VAC source, NOT split with each half going from the two
sources to neutral. (That would require a double contact to
turn each PAIR of heating elements on and off.)

I'm not sure what you're talking about. First, there is no "240V"
source in
my condo. There are multiple 120V sources from which you can get higher
voltages by spanning them. (I assume each voltage is referenced to some
"neutral" point.) In my preceding apartment, I took advantage of this to
build a break-out box -- all to code, I have several electrician
friends who
advised me -- to provide individual lines for my class A power amps.

As someone else kindly pointed out, this oven has one side of its
elements
hard-wired to AC. Bad, bad, bad, bad idea.

Damn you are ****ing dense William.

The heating element from one hot lead to the other hot lead.
At NO time is there a connection to Neutral. Hence it ONLY
requires a SINGLE pole switch to open a SERIES circuit.

I see no inconsistency. A correctly functioning heating element can be
turned off, in the sense of no longer heating, by means of a single pole
switch.

But what about a non-correctly functioning heating element? One, for
example, that's shorted to its grounded covering somewhere along its
length. This could result in part of the element overheating, and an
owner noticing this would likely respond by turning the appliance off at
its switch. In the case of a heating element that spans two 110 v lines
in opposite phase, turning it off by a single pole switch won't have the
desired effect. Better hope that an earth leakage detector is fitted in
the supply lines, and works.

Sylvia.

I had exactly this happen over a decade ago. *The center resistance
element started arcing to the outer sheath. *This action was clearly
visible. *When turning off the oven didn't help, I did what any
intelligent person should do - I turned off the circuit breaker.

I repeat - only a fool works on electrical equipment without making
sure it has been disconnected from power. *'Assuming' that both sides
of the power line are switched is stupid. Beleiving that the circuit
breaker is correctly labeled is foolish. Trusting the circuit breaker
is working correctly is only slightly less so.

About 5 years ago a lady named Gina Marie Wylie published an online
serial called 'Spitfire and Messerschmidt'. *In the story, an Air
Conditioning serviceman is called upon to determine why the central
air conditioner has stopped. *In exquisite detail it is described how
he checked the thermostat, then turned off the circuit breaker, pulled
the access panel, then used a voltmeter to verify the power was off.
When Davey (AKA Messerschmidt) questions this, the serviceman explains
"I have a six year old son. *I look forward to going home and playing
with him tonight. *I don't want someone to have to explain to him that
Daddy was in a hurry, made a mistake, and won't ever be coming home."

* I'm sure the OP's significant other would not be comforted by the
epitath 'I thought it was turned off.'

PlainBill

That was one of the best things said so far. I heard about a utility
worker who walked into 1100VAC at a sub station some years ago. He too
thought that "the power was off". He spent the rest of his short life
on life support. We shouldn't need to be given a reason to be safe but
just in case someone does, just read 'Spitfire and Messerschmidt'.

You know William it seems that we like to buy the same appliances. I
also had a Black and Decker toaster oven some years ago and I too
remember that both sides of the line were switched off when you opened
the door. (I burnished and bent those contacts many times until they
just eventually "evaporated" and we had to throw the damn toaster
out). But after thinking about it, what puzzles me now is why did they
bother to switch both a 120V hot as well as a neutral? I still think
that it's prudent to disconnect power before working on something,
(whenever you can that is), but it seems to make no sense to
disconnect a neutral on a 120V circuit considering they can't be
bothered to disconnect both sides of the line on a 240V appliance.
Lenny
Lenny

"klem kedidelhopper" wrote in message
...

You know William it seems that we like to buy the same appliances.
I also had a Black and Decker toaster oven some years ago and I too
remember that both sides of the line were switched off when you opened
the door. (I burnished and bent those contacts many times until they
just eventually "evaporated" and we had to throw the damn toaster
out). But after thinking about it, what puzzles me now is why did they
bother to switch both a 120V hot as well as a neutral? I still think
that it's prudent to disconnect power before working on something,
(whenever you can that is), but it seems to make no sense to
disconnect a neutral on a 120V circuit considering they can't be
bothered to disconnect both sides of the line on a 240V appliance.

I can think of a number of reasons, the principal one being that it's easy
to stick a fork in a toaster, much harder to stick one in an oven. Of
course, this particular toaster used sealed elements, so it's unlikely
anything within the cavity would ever be electrically hot.

The other reason for switching the neutral is that there's no guarantee the
neutral is neutral -- some houses are miswired.

I had a great conversation the other day with a woman at GE's CEO
headquarters, who apparently does nothing but talk to Really Unhappy
customers. I admitted my carelessness, but she didn't put me down, and
listened seriously. She said she would report this to The Council. ("The
Kryptonian Council of Elders?" That got a big laugh out of her.) Apparently,
GE has a group that pays attention to engineering issues.

You might have heard that GE is bringing major-appliance manufacturing back
to Appliance Park. This is apparently due to rising wages in other
countries, and GE's figuring out how to build appliances more efficiently. A
guy at GE told me that the goal is return the manufacture of /all/ major
appliances.

On Jun 25, 11:08*am, "William Sommerwerck"
wrote:
"klem kedidelhopper" wrote in message

...

You know William it seems that we *like to buy the same appliances.
I also had a Black and Decker toaster oven some years ago and I too
remember that both sides of the line were switched off when you opened
the door. (I burnished and bent those contacts many times until they
just eventually "evaporated" and we had to throw the damn toaster
out). But after thinking about it, what puzzles me now is why did they
bother to switch both a 120V hot as well as a neutral? I still think
that it's prudent to disconnect power before working on something,
(whenever you can that is), but it seems to make no sense to
disconnect a neutral on a 120V circuit considering they can't be
bothered to disconnect both sides of the line on a 240V appliance.

I can think of a number of reasons, the principal one being that it's easy
to stick a fork in a toaster, much harder to stick one in an oven. Of
course, this particular toaster used sealed elements, so it's unlikely
anything within the cavity would ever be electrically hot.

The other reason for switching the neutral is that there's no guarantee the
neutral is neutral -- some houses are miswired.

I had a great conversation the other day with a woman at GE's CEO
headquarters, who apparently does nothing but talk to Really Unhappy
customers. I admitted my carelessness, but she didn't put me down, and
listened seriously. She said she would report this to The Council. ("The
Kryptonian Council of Elders?" That got a big laugh out of her.) Apparently,
GE has a group that pays attention to engineering issues.

You might have heard that GE is bringing major-appliance manufacturing back
to Appliance Park. This is apparently due to rising wages in other
countries, and GE's figuring out how to build appliances more efficiently.. A
guy at GE told me that the goal is return the manufacture of /all/ major
appliances.

So then why not assume that there are enough idiots out there like
people who use ground busters because they have older ungrounded
outlets in their homes or better yet those that file the larger prong
on a plug down so that it will fit in an older outlet. If you really
consider these possibilities then why not switch both the hot and
neutral on every 120V appliance. Lets make them all "idiot proof" and
then everyone will be safe. I mean should we assume that anyone is
going to have to take responsibility for their own actions any more?
When I was a kid, (back in the stone age). there was no such thing as
a Calrod element, well maybe there might have been but I remember that
most appliances like toasters, ovens, broilers, even space heaters
were made with exposed nichrome wire. Many toasters still are. I
worked on them all from the time I was a teenager. Most people, even
the non technical ones realized after they had stuck a fork in the
toaster once to not do that again. I'm sure that they still do. But
really lets answer the bigger question. What is the goal here? Is it
to build an appliance as cheaply, I'm sorry, (cost effectively), as
possible or is it to keep people, even the stupid ones safe? And
getting back to my other question: why did B& D obviously think that
it was a good idea 15 years ago to switch both the hot and neutral on
my toaster oven but now they don't?
You just can't convince me that the least common denominator isn't
money. Yeah maybe I am a little paranoid too, but it doesn't mean
they're not out to get me.....Lenny

"klem kedidelhopper" wrote in message
...

When I was a kid, (back in the stone age). there was no such thing as
a Calrod element, well maybe there might have been but I remember that
most appliances like toasters, ovens, broilers, even space heaters
were made with exposed nichrome wire.

The GE Calrod unit goes back at least to the 50s, and probably the 30s. An
electric oven using exposed nichrome wires would not be a very good idea.

Many toasters still are. I
worked on them all from the time I was a teenager. Most people, even
the non technical ones realized after they had stuck a fork in the
toaster once to not do that again. I'm sure that they still do. But
really lets answer the bigger question. What is the goal here? Is it
to build an appliance as cheaply, I'm sorry, (cost effectively), as
possible or is it to keep people, even the stupid ones safe? And
getting back to my other question: why did B& D obviously think that
it was a good idea 15 years ago to switch both the hot and neutral on
my toaster oven but now they don't?

If there is an answer, it's that you do certain things simply because they
make sense, regardless of what you think a user might or might not do.


You just can't convince me that the least common denominator isn't
money. Yeah maybe I am a little paranoid too, but it doesn't mean
they're not out to get me.....Lenny

On Jun 25, 4:57*pm, "William Sommerwerck"
wrote:
"klem kedidelhopper" wrote in message

...

When I was a kid, (back in the stone age). there was no such thing as
a Calrod element, well maybe there might have been but I remember that
most appliances like toasters, ovens, broilers, even space heaters
were made with exposed nichrome wire.

The GE Calrod unit goes back at least to the 50s, and probably the 30s. An
electric oven using exposed nichrome wires would not be a very good idea.

Many toasters still are. I
worked on them all from the time I was a teenager. Most people, even
the non technical ones realized after they had stuck a fork in the
toaster once to not do that again. I'm sure that they still do. But
really lets answer the bigger question. What is the goal here? Is it
to build an appliance as cheaply, I'm sorry, (cost effectively), as
possible or is it to keep people, even the stupid ones safe? And
getting back to my other question: why did B& D obviously think that
it was a good idea 15 years ago to switch both the hot and neutral on
my toaster oven but now they don't?

If there is an answer, it's that you do certain things simply because they
make sense, regardless of what you think a user might or might not do.

You just can't convince me that the least common denominator isn't
money. Yeah maybe I am a little paranoid too, but it doesn't mean
they're not out to get me.....Lenny

I have my mother's old broiler/rotisserie from the 50's down in the
basement. My wife asked me to get rid of it so many times but I just
can't seem to part with it. (I remember the roasts and rotisserie
chickens we used to have when I was a kid). It has a coiled nichcrome
wire element as they all did at that time. Early Lionel trains were
connected directly to the AC line through a carbon pile or rheostat.
Things were a lot different in "the old days". I finally just hid it.
Maybe I'll get it out one day and cook a roast for her. Lenny

On Jun 25, 4:57*pm, "William Sommerwerck"
wrote:
"klem kedidelhopper" wrote in message

...

When I was a kid, (back in the stone age). there was no such thing as
a Calrod element, well maybe there might have been but I remember that
most appliances like toasters, ovens, broilers, even space heaters
were made with exposed nichrome wire.

The GE Calrod unit goes back at least to the 50s, and probably the 30s. An
electric oven using exposed nichrome wires would not be a very good idea.

Many toasters still are. I
worked on them all from the time I was a teenager. Most people, even
the non technical ones realized after they had stuck a fork in the
toaster once to not do that again. I'm sure that they still do. But
really lets answer the bigger question. What is the goal here? Is it
to build an appliance as cheaply, I'm sorry, (cost effectively), as
possible or is it to keep people, even the stupid ones safe? And
getting back to my other question: why did B& D obviously think that
it was a good idea 15 years ago to switch both the hot and neutral on
my toaster oven but now they don't?

If there is an answer, it's that you do certain things simply because they
make sense, regardless of what you think a user might or might not do.

You just can't convince me that the least common denominator isn't
money. Yeah maybe I am a little paranoid too, but it doesn't mean
they're not out to get me.....Lenny

I had another question as long as we're talking about ovens. When you
use the self cleaning function on these stoves, I believe that both
elements are turned on for an extended period of time. We usually hold
off doing this until a cold spell hits as lot of heat is generated and
warms the kitchen nicely. Essentially everything in the oven is
incinerated down to a fine gray powder. If you think of the bake and
broil elements as "filaments" of a sort, with a finite life span,
doesn't invoking this function shorten their life? Lenny

On 6/26/2011 10:44 PM, klem kedidelhopper wrote:
I had another question as long as we're talking about ovens. When you
use the self cleaning function on these stoves, I believe that both
elements are turned on for an extended period of time. We usually hold
off doing this until a cold spell hits as lot of heat is generated and
warms the kitchen nicely. Essentially everything in the oven is
incinerated down to a fine gray powder. If you think of the bake and
broil elements as "filaments" of a sort, with a finite life span,
doesn't invoking this function shorten their life? Lenny

One would think so, if one were inclined to think all corporations are
evil and all design engineers are stupid.

The misconception here is that the "normal" heating range on those
elements is the design center. It is NOT. The "clean" cycle is the
design center.

Jeff

--
"Everything from Crackers to Coffins"

"Jeffrey Angus" wrote in message
...
On 6/26/2011 10:44 PM, klem kedidelhopper wrote:

I had another question as long as we're talking about ovens. When
you use the self cleaning function on these stoves, I believe that both
elements are turned on for an extended period of time. We usually
hold off doing this until a cold spell hits as lot of heat is generated
and warms the kitchen nicely. Essentially everything in the oven is
incinerated down to a fine gray powder. If you think of the bake and
broil elements as "filaments" of a sort, with a finite life span,
doesn't invoking this function shorten their life?

If it does, then one has to weigh the convenience of self-cleaning against
the inconvenience and higher cost of manual cleaning.


One would think so, if one were inclined to think all corporations are
evil and all design engineers are stupid.

The misconception here is that the "normal" heating range on those
elements is the design center. It is NOT. The "clean" cycle is the
design center.

I've never used the self-cleaning feature on my oven. Yet the bottom element
burned through after only about 10 years of use. Another member of this
group reported the same thing for their GE.

I had a conservative, slightly paranoid friend (hi, Greg -- miss ya bad) who
claimed materials science was sufficiently advanced that auto manufacturers
were able to control how long a car engine lasted. I pooh-poohed this, but
he was probably correct. Few products are made to last "as long as
possible", because it tends to increase the price.

On 6/27/2011 8:03 AM, William Sommerwerck wrote:
I had a conservative, slightly paranoid friend (hi, Greg -- miss ya bad) who
claimed materials science was sufficiently advanced that auto manufacturers
were able to control how long a car engine lasted. I pooh-poohed this, but
he was probably correct. Few products are made to last "as long as
possible", because it tends to increase the price.

It's NOT some evil conspiracy.

The CONSUMER has been screaming for the past 30 years,
"I don't care if it's crap, I want it now, I want it
cheap and I don't care if it only last 6 months because
I'll be bored with it by then anyway."

Manufacturers are supplying them with what they asked for.

Jeff


--
"Everything from Crackers to Coffins"

On Mon, 27 Jun 2011 10:11:59 -0500, Jeffrey Angus
wrote:

On 6/27/2011 8:03 AM, William Sommerwerck wrote:
I had a conservative, slightly paranoid friend (hi, Greg -- miss ya bad) who
claimed materials science was sufficiently advanced that auto manufacturers
were able to control how long a car engine lasted. I pooh-poohed this, but
he was probably correct. Few products are made to last "as long as
possible", because it tends to increase the price.

It's NOT some evil conspiracy.

The CONSUMER has been screaming for the past 30 years,
"I don't care if it's crap, I want it now, I want it
cheap and I don't care if it only last 6 months because
I'll be bored with it by then anyway."

Manufacturers are supplying them with what they asked for.

Not exactly. In the not so distant past, manufacturers produced
products, set prices as best they could, and retailers did their best
to sell at that price point. No more. With the demise of the small
retailers, the large warehouse stores are doing it backwards. They
set a price at which they know they can sell and make a profit, and
then demand that their suppliers deliver at that price. If the
supplier complains, then another supplier will be found. Walmart is
famous for doing that. The result is that manufacturers have
cheapened their products, reduced the quality, cut corners, deleted
options, etc. Anything to meet the price target. If there are any
subsequent quality problems, it's cheaper to deal with warranty
returns, than to design in the necessary quality that prevent returns.

I see something quite different than customers that get bored in 6
months. I get complaints that it only lasts 6 months and that they
want quality at any price. I deliver quite a few overkill computer
systems, where a lesser machine would have been more than adequate. I
see hybrid auto sales doing quite well, mostly on the basis of quality
and alleged economy, where both would be difficult to innumerate and
financially justify. The GUM (great unwashed masses) may have been
demanding cheap junk for 30 years, but now seem to have begun to tire
of the junk.

As for controlling product lifetime, it's been here for quite a while.
Semiconductor life can be predicted based on the number of thermal
cycles. Electrolytic capacitor life can be predicted by a combination
of temperature and operating conditions. Battery lifetimes are well
known and controllable. High power LED's have a predictable lifetime.
I've seen products (i.e. old Sony TV's and monitors) that seem to have
had components selected for a specific target lifetime. Modeling
programs make such designs fairly easy.




--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

Jeff Liebermann wrote:

They
set a price at which they know they can sell and make a profit, and
then demand that their suppliers deliver at that price. If the
supplier complains, then another supplier will be found. Walmart is
famous for doing that. The result is that manufacturers have
cheapened their products, reduced the quality, cut corners, deleted
options, etc. Anything to meet the price target. If there are any
subsequent quality problems, it's cheaper to deal with warranty
returns, than to design in the necessary quality that prevent returns.

It's a lot older than you think. Around 1980 or so, Sears wanted to sell a
black and white portable TV and they could not get anyone in the US or Japan
to sell them one.

They shopped around and found Samsung, which was a large company in Korea,
but unheard of outside who was willing to do it. That's when the large
international Korean electronics giants were born.

As for quality programs, it's not the build quality that matters as much
as you think. It's the testing. Intel started it (although they may probably
were not the first) when they produced RAM chips for the IBM PC and other
small computers.

The only made only produced one chip speed and if the chips failed, they were
tested at a slower speed, if they failed that they were tested until they
failed at the slowest speed sold, or passed one of the tests.

They actually had to do it, their first chips were so bad that ECC (error
correcting code) processing had to be built into the hardware of the first
computer made using them. It was done at the XEROX PARC, you can read about
it in "Dealers in Lightening".

Now they don't bother to test anything at the manufacturing plant, the
consumer tests it for them. :-(

Geoff.

--
Geoffrey S. Mendelson N3OWJ/4X1GM
Making your enemy reliant on software you support is the best revenge.

"Jeff Liebermann" wrote in message
news
In the not so distant past, manufacturers produced
products, set prices as best they could, and retailers did their best
to sell at that price point. No more. With the demise of the small
retailers, the large warehouse stores are doing it backwards. They
set a price at which they know they can sell and make a profit, and
then demand that their suppliers deliver at that price. If the
supplier complains, then another supplier will be found. Walmart is
famous for doing that.

Wal*mart also (supposedly) insists that suppliers reduce their prices every
year.

I know of no other "big box" store that does these things.

I've been in Wal*mart a few times, and I didn't see where their prices were
categorically lower than other stores'. Regardless, I don't buy from
Wal*mart.

I'm old enough to remember when discounting was uncommon. Luskin's ("Jack
and Joe will save you dough.") of Baltimore was one of the first stores in
the US to discount appliances, electronics, etc. It's now taken for granted
that you don't pay "list price" for anything -- assuming that "list price"
has any meaning.


The result is that manufacturers have
cheapened their products, reduced the quality, cut corners, deleted
options, etc. Anything to meet the price target. If there are any
subsequent quality problems, it's cheaper to deal with warranty
returns, than to design in the necessary quality that prevent returns.

In the case of Wal*mart, the story goes that companies are sometimes forced
to send production overseas.


I see something quite different than customers that get bored in 6
months. I get complaints that it only lasts 6 months and that they
want quality at any price. I deliver quite a few overkill computer
systems, where a lesser machine would have been more than adequate. I
see hybrid auto sales doing quite well, mostly on the basis of quality
and alleged economy, where both would be difficult to innumerate and
financially justify. The GUM (great unwashed masses) may have been
demanding cheap junk for 30 years, but now seem to have begun to tire
of the junk.

Again, I'm not sure. If that were so, there wouldn't be any $30 DVD players
at Fry's.

Cheap merchandise -- of whatever quality -- is part of the "vicious circle"
of rapid technological change and obsolesence.

In article ,
Jeff Liebermann wrote:

As for controlling product lifetime, it's been here for quite a while.
Semiconductor life can be predicted based on the number of thermal
cycles. Electrolytic capacitor life can be predicted by a combination
of temperature and operating conditions. Battery lifetimes are well
known and controllable. High power LED's have a predictable lifetime.
I've seen products (i.e. old Sony TV's and monitors) that seem to have
had components selected for a specific target lifetime. Modeling
programs make such designs fairly easy.

Henry Ford ("Ford: The Men and the Machine" is an outstanding book, but
don't waste your time with the movie) sent roving teams of engineers out
to the junkyards of America to dismantle junked Fords and see which
parts were still good. One thing they couldn't find was a worn-out
kingpin, so Ford started making them lighter and cheaper. No sense
having a kingpin outlive the car. That was close to 100 years ago.

"Smitty Two" wrote in message
news
In article ,
Jeff Liebermann wrote:

As for controlling product lifetime, it's been here for quite a while.
Semiconductor life can be predicted based on the number of thermal
cycles. Electrolytic capacitor life can be predicted by a combination
of temperature and operating conditions. Battery lifetimes are well
known and controllable. High power LED's have a predictable lifetime.
I've seen products (i.e. old Sony TV's and monitors) that seem to have
had components selected for a specific target lifetime. Modeling
programs make such designs fairly easy.

Henry Ford ("Ford: The Men and the Machine" is an outstanding book, but
don't waste your time with the movie) sent roving teams of engineers out
to the junkyards of America to dismantle junked Fords and see which
parts were still good. One thing they couldn't find was a worn-out
kingpin, so Ford started making them lighter and cheaper. No sense
having a kingpin outlive the car. That was close to 100 years ago.

Which strikes me as perverse -- why not improve the quality of those parts
that were worn out? Oh, wait... cars would last longer, and there would be
fewer sales, over time.

On Tue, 28 Jun 2011 05:44:04 +0000 (UTC), "Geoffrey S. Mendelson"
wrote:

Now they don't bother to test anything at the manufacturing plant, the
consumer tests it for them. :-(

Quite true. Modern robotic manufacturing methods have the advantage
of producing fairly uniform output. The 1.5% AQL QA test is somewhat
of a thing of the past, as it's only necessary to test a tiny number
of sample units, to predict the performance of the rest.

From my experience, in the distant past, 100% parametric (partial)
testing of the product along the production line gives better results.
This is where key parts of the PCB are indirectly tested during board
assembly, but before final assembly. Tests such as total current
drain, end to end gain, board weight, and visual (camera) inspection,
do not provide a complete test, but give a fair indication if the PCB
is going to work. The idea is to eliminate final test, which such
methods do fairly well. The assumption is that a collection of small
tests during assembly, do better than a final test. To the casual
observer, it may look bad that there's no final test, but along the
board assembly line, there's plenty of testing being done.
Incidentally, some robotic parts stuffers test the components as they
are inserted in the PCB.

--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

On Tue, 28 Jun 2011 02:47:38 -0700, "William Sommerwerck"
wrote:

Wal*mart also (supposedly) insists that suppliers reduce their prices every
year.

Walmart offers the suppliers increased sales volume in trade for a
decreased profit margin. That will work only if the supplier has an
efficiency improvement program in place. It will also only work with
suppliers that are large enough to have sufficient credit available to
fund such programs. That eliminates all but the largest suppliers.

The dilemma for Walmart is that there are really only a few vendors
qualified to sell to Walmart under such a program. There's also
little to stop them from illegally organizing and fixing prices. When
this happens, Walmart finds a medium size supplier, and offers to back
their growth into a large supplier, in trade for profit margin
concessions. How it works in Mexico:
http://econ.la.psu.edu/~jtybout/SDS%20and%20NAFTA_NBER.pdf
The US gets cheap Mexican products, while Mexico gets Walmart.

I know of no other "big box" store that does these things.

My father sold lingerie to Sears during the 1960's thru mid 1980's.
Sears wasn't as obnoxious and as demanding as Walmart, but such
pricing policies (and others) were well established. However, Sears
had a different goal. They were not after the best price. They were
into growth. What they did was build up the business of their
suppliers, knowing that the supplier would need to obtain expensive
financing, and then abruptly cut off all orders. They could then buy
what was left of their supplier for peanuts.

In the case of Wal*mart, the story goes that companies are sometimes forced
to send production overseas.

Most domestic companies would prefer to use domestic production
facilities. It can be done, but not at the price points set by
Walmart. Similarly, if the competition wants to sell anywhere near
the same price point, they too have to go offshore, even if they don't
sell to Walmart.

Cheap merchandise -- of whatever quality -- is part of the "vicious circle"
of rapid technological change and obsolesence.

Good, fast, cheap.... pick two. The buying public has chosen fast and
cheap, so the quality will suffer. Where problems start is when
quality is unobtainable at any price. That's where I think we're
going.


--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

On Tue, 28 Jun 2011 02:47:38 -0700, "William Sommerwerck"
wrote:

Wal*mart also (supposedly) insists that suppliers reduce their prices every
year.

It's not just Walmart. Here's Apple demanding what appears to be
regular price cuts on iPad components:
Report: Apple Demands 10 Percent Price Cuts from iPad
Parts Suppliers
http://www.pcmag.com/article2/0,2817,2387397,00.asp

--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

"Jeff Liebermann" wrote in message
...

Cheap merchandise -- of whatever quality -- is part of the
"vicious circle" of rapid technological change and obsolesence.

Good, fast, cheap.... pick two. The buying public has chosen fast
and cheap, so the quality will suffer. Where problems start is when
quality is unobtainable at any price. That's where I think we're going.

Regardless of whether this is true or false, it's definitely has hurt Sony,
which depended on its premium products to create a favorable image for
everything it sold.

Sony used to be a true innovator that make a lot of Neat Stuff, but those
days seem gone. Glad I got a 7M3 AIBO while they were still available.

Jeffrey Angus wrote:
On 6/21/2011 7:25 AM, William Sommerwerck wrote:
"Jeffrey wrote in message
...
On 6/20/2011 10:36 PM, William Sommerwerck wrote:

Why don't you stop by, and I'll pull out the heating element part way.
Then you can touch one of the wires feeding the element with one hand,
and the a ground (such as the oven cabinet) with your other other hand.

Care to bet your life on it?

I'd be happy to, idiot. I have enough sense to disconnect it first.

Oh. I thought all that was needed was to disconnect one side.

Uh huh, you're purposely talking in circles here....

You only have to disconnect one side to make the heater not heat.
You have to disconnect BOTH sides to make sure it's doesn't have
power on it to safely service the unit.

From my perspective, the issue is this... There are certain design rules you
follow, simply because they're common sense. That's it.

My toaster oven doesn't shut off when you open the door, either because B&D
was cheap, or the designer didn't think anything bad would ever happen.
Older models did, including ones with sealed heating elements.

Does you gas oven shut it self off when you open the door?

Ha!

On Jun 19, 1:42*pm, Sylvia Else wrote:
On 19/06/2011 1:20 PM, William Sommerwerck wrote:

I should have explained that I went to remove the element without
opening the breaker -- on the assumption that no engineer in his
right mind would leave one side of the heating element powered.

Are you stupid? NOTHING gets worked on while connected to power.

"Foolish" might be more apt than "stupid". And people commonly work on
powered TVs and other electronic equipment -- with proper precautions, of
course.

We still need an answer to the original question... Why?

I think it's perfectly normal for appliances to switch only one pole of
the power supply, that pole being the live one. Same with power points
and light switches. I don't think I've seen an appliance with a double
power power switch.

What's not normal, and dangerous, is for the neutral wire to be the one
switched. Either the oven is miswired internally, is miswired to the
mains supply, or the mains supply is miswired. Whichever it is needs to
be fixed.

Sylvia.


I think you will find that this is in the USA, They have 2 x 120v 180
out of phase, and
if you go across the 2 actives you get 240v. This is used on
appliances like this and
air cons that suck a lot of power, in order to reduce the currents
involved.

It would be like 3 phase here, but we have 3 actives and 120
separation. Same rule,
ALL 3 phases must be turned off or the appliance is still "live"

On Jun 19, 8:40*pm, "William Sommerwerck"
wrote:
"Sylvia Else" wrote in message

...

On 19/06/2011 1:20 PM, William Sommerwerck wrote:
We still need an answer to the original question... Why?
I think it's perfectly normal for appliances to switch only one pole
of the power supply, that pole being the live one. Same with power
points and light switches. I don't think I've seen an appliance with
a double power power switch.

I have have. I've owned two of the classic GE/B&D toaster ovens, and they
switched both sides of the line when you opened the door. This is a good
safety precaution. My current B&D toaster oven does not remove the power
when the door is opened.

With respect to this particular oven, something "live" was NOT being
switched. How do you explain the spark, otherwise? The 208V or 240V are
(presumably) taken from across two phases (or whatever you want to call
them -- we needn't rehash that argument), one of which is not switched. The
oven's "metalwork" is grounded/"neutraled" so that a short from the
heating-element circuit to the metal will trip the breaker -- which it did.

What's not normal, and dangerous, is for the neutral wire to be the
one switched. Either the oven is miswired internally, is miswired to
the mains supply, or the mains supply is miswired. Whichever it is
needs to be fixed.

If I understand multi-phase wiring, the 240V is taken from across two
phases. Connecting or disconnecting the neutral would have no effect on that
voltage.

In single-phase systems, it would, of course, be foolish to switch just the
neutral. This would leave the hot "hot", and open the possibility of
electrocution from hot to ground, such as a plumbing fixture.


Believe it or not, I have seen in the past, appliances where the
neutral was switched
I was told that this was a tactic to allow a lower rated switch to be
used.

Same with old Ferguson fluorescent ballasts in common use in the
`1960-70s
The diagram on them showed them wired into the neutral supply with the
live coming
through the tube. Probably again to lower rate the thing ?



Yet again, an example of how a simple question becomes a tsimmes.