On Sat, 07 Nov 2015 22:52:34 -0000, Rod Speed wrote:



"Tough Guy no. 1265" wrote in message
news
On Sat, 07 Nov 2015 21:48:17 -0000, Rod Speed
wrote:



"Tough Guy no. 1265" wrote in message
news On Sat, 07 Nov 2015 20:28:36 -0000, Rod Speed
wrote:



"Tough Guy no. 1265" wrote in message
news On Sat, 07 Nov 2015 19:37:55 -0000, Cursitor Doom

wrote:

On Sat, 07 Nov 2015 16:42:20 +0000, Tough Guy no. 1265 wrote:

I looked this up, I'm asking the question at the top. The replies
don't
seem to be able to agree. Any sensible opinions?

http://electronics.stackexchange.com...hy-are-we-not-
always-isolating-the-mains-supply

In repair & testing scenarios, we use isolation transformers to
remove
the Earth reference. It prevents ground loops arising which can
destroy
sensitive test equipment. But an IT won't save you from a belt if you
somehow manage to bridge directly across it.

No it won't, but it won't make it any worse, it'll be identical. But
it
does remove the shock from live to ground, which is more likely as
only
one conductor has to be touched.

But the cost of a ****ing great transformer for the entire house
and the losses involved in that don't warrant the tiny increase
safety. Makes more sense to use RCDs and double insulated
smaller appliances instead.

No more transformers required,

Wrong.

simply have the output of the substation not connected to ground.

Wouldn't stop people getting electrocuted.

Yes it would, because the live has no voltage WRT ground anymore.

Wrong when its done at the substation for hundreds of houses.

That's actually LESS wiring.

Wrong again.

Same number of cables coming to each house, count them.

Same number isn't LESS wiring, stupid.

In the house, all the cables could be TWO core.

--
While the Swiss Army Knife has been popular for years, the Swiss Navy Knife has remained largely unheralded.
Its single blade functions as a tiny canoe paddle.

On Sat, 07 Nov 2015 22:11:59 +0000, Mr Pounder Esquire wrote:

Why are you feeding phucker?
All this dick wants is an argument.

He has earned a lot of political cred here. Unlike some.

"Tough Guy no. 1265" wrote in message
news
On Sat, 07 Nov 2015 21:52:56 -0000, Rod Speed
wrote:



"Tough Guy no. 1265" wrote in message
news
On Sat, 07 Nov 2015 20:33:48 -0000, Rod Speed
wrote:



"Tough Guy no. 1265" wrote in message
news On Sat, 07 Nov 2015 20:05:02 -0000, Fredxxx wrote:

On 07/11/2015 19:07, Tough Guy no. 1265 wrote:
On Sat, 07 Nov 2015 18:14:59 -0000, harry

wrote:

On Saturday, 7 November 2015 16:42:25 UTC, Tough Guy no. 1265
wrote:
I looked this up, I'm asking the question at the top. The replies
don't seem to be able to agree. Any sensible opinions?

http://electronics.stackexchange.com...e-mains-supply


--
It said, "Insert disk #3," but only two will fit!

It is important when electrical equipment/appliances have metal
cabinets which can be earthed. Which was everything years ago.
Without an earth, ant fault to the cabinet could not be detected
and
would be dangerous if there were other earth faults.
Also get over certain capacitance effects.

Two faults is unlikely. One fault would of course not shock you at
all. Most shocks are an exposed live to an earth, isolating the
mains
would remove that possibility altogether, and not change the amount
of
shocks between live and neutral.

I would agree with you, but only if you can automatically detect each
of
the faults and interrupt the power accordingly.

An isolation transformer might well hide some faults as well as
introducing some more and so be more dangerous in reality than the
conventional single phase supply.

But the two faults would have to be within reach of each other, eg
your
washing machine and your fridge both having a fault with the opposite
conductor, and you touch both. So very unlikely.

Not as unlikely with a couple of small appliances in the kitchen.

I have never had ONE appliance get live on its chassis,

It happens anyway.

Not as often as other problems.

That is very arguable given that hardly anyone is actually stupid
enough to mow their lawn with electric lawn mowers etc.

And even if it was less common, still worth protecting against.

nevermind two.

You don't need two, in fact two would be safe. The problem is with
one with a live case and all the others with an earthed case and other
earthed stuff like the sink etc.

No, because with isolation you don't have earths everywhere.

Wrong again. You still need to earth the case so that if a
live does come adrift, it takes the fuse out or the RCD.

You'd have to therefore have two faults, one with live to chassis and one
with neutral to chassis.

Wrong, as always.

Besides, I've never actually observed a fault where the chassis
becomes
live.

Doesn't matter what you have observed, the design
of the system has to allow for that situation.

Why allow for a remote possibility, thereby creating a very likely one
of
live to the ground?

The only shocks I've ever had were worn cables on a mower, touching a
switch with wet hands when outside, etc.

A wire does come adrift inside an appliance quite a bit.

No,

Yep.

because they are inside and don't get touched.

They touch the case and that is a problem.

They come adrift when the wire comes out of what its
supposed to be attached to and when cord anchor isn't
good enough and some fool lets it fall off the bench
and hang on the cord etc.

Usually the cord then yanks out the other conductors and live and neutral
short,

Hardly ever.

blowing the fuse.

What actually blows the fuse or trips the
RCD is the active contacting the earthed case.

On Sat, 07 Nov 2015 22:56:53 -0000, Cursitor Doom wrote:

On Sat, 07 Nov 2015 21:47:18 +0000, Tough Guy no. 1265 wrote:

Isolated mains IMPROVES safe tea.

I suppose these days with more and more STUFF coming in double-insulated
plastic encapsulations, there may be SOME merit to your argument. We'll
just prematurely scrap all the metal-cased appliances, then. Happy?

Isolated mains improves safety with those too.

--
Q. What's the difference between a brown-noser and a ****-head?
A. Depth perception.

**** snipped

"Tough Guy no. 1265" wrote in message
news
On Sat, 07 Nov 2015 22:52:34 -0000, Rod Speed
wrote:



"Tough Guy no. 1265" wrote in message
news
On Sat, 07 Nov 2015 21:48:17 -0000, Rod Speed
wrote:



"Tough Guy no. 1265" wrote in message
news On Sat, 07 Nov 2015 20:28:36 -0000, Rod Speed

wrote:



"Tough Guy no. 1265" wrote in message
news On Sat, 07 Nov 2015 19:37:55 -0000, Cursitor Doom

wrote:

On Sat, 07 Nov 2015 16:42:20 +0000, Tough Guy no. 1265 wrote:

I looked this up, I'm asking the question at the top. The replies
don't
seem to be able to agree. Any sensible opinions?

http://electronics.stackexchange.com...hy-are-we-not-
always-isolating-the-mains-supply

In repair & testing scenarios, we use isolation transformers to
remove
the Earth reference. It prevents ground loops arising which can
destroy
sensitive test equipment. But an IT won't save you from a belt if
you
somehow manage to bridge directly across it.

No it won't, but it won't make it any worse, it'll be identical.
But
it
does remove the shock from live to ground, which is more likely as
only
one conductor has to be touched.

But the cost of a ****ing great transformer for the entire house
and the losses involved in that don't warrant the tiny increase
safety. Makes more sense to use RCDs and double insulated
smaller appliances instead.

No more transformers required,

Wrong.

simply have the output of the substation not connected to ground.

Wouldn't stop people getting electrocuted.

Yes it would, because the live has no voltage WRT ground anymore.

Wrong when its done at the substation for hundreds of houses.

Explain.

That's the reason NO ONE does it the way you want it done WORLD WIDE.

That's actually LESS wiring.

Wrong again.

Same number of cables coming to each house, count them.

Same number isn't LESS wiring, stupid.

No grounding point required.

That doesn't involve any street wiring.

"Tough Guy no. 1265" wrote in message
news
On Sat, 07 Nov 2015 22:52:34 -0000, Rod Speed
wrote:



"Tough Guy no. 1265" wrote in message
news
On Sat, 07 Nov 2015 21:48:17 -0000, Rod Speed
wrote:



"Tough Guy no. 1265" wrote in message
news On Sat, 07 Nov 2015 20:28:36 -0000, Rod Speed

wrote:



"Tough Guy no. 1265" wrote in message
news On Sat, 07 Nov 2015 19:37:55 -0000, Cursitor Doom

wrote:

On Sat, 07 Nov 2015 16:42:20 +0000, Tough Guy no. 1265 wrote:

I looked this up, I'm asking the question at the top. The replies
don't
seem to be able to agree. Any sensible opinions?

http://electronics.stackexchange.com...hy-are-we-not-
always-isolating-the-mains-supply

In repair & testing scenarios, we use isolation transformers to
remove
the Earth reference. It prevents ground loops arising which can
destroy
sensitive test equipment. But an IT won't save you from a belt if
you
somehow manage to bridge directly across it.

No it won't, but it won't make it any worse, it'll be identical.
But
it
does remove the shock from live to ground, which is more likely as
only
one conductor has to be touched.

But the cost of a ****ing great transformer for the entire house
and the losses involved in that don't warrant the tiny increase
safety. Makes more sense to use RCDs and double insulated
smaller appliances instead.

No more transformers required,

Wrong.

simply have the output of the substation not connected to ground.

Wouldn't stop people getting electrocuted.

Yes it would, because the live has no voltage WRT ground anymore.

Wrong when its done at the substation for hundreds of houses.

That's actually LESS wiring.

Wrong again.

Same number of cables coming to each house, count them.

Same number isn't LESS wiring, stupid.

In the house, all the cables could be TWO core.

Wrong. You'd still need to earth the body
of all those non double insulated devices.

"Tough Guy no. 1265" wrote in message
news
On Sat, 07 Nov 2015 22:54:34 -0000, Rod Speed
wrote:



"Tough Guy no. 1265" wrote in message
news
On Sat, 07 Nov 2015 21:46:51 -0000, Rod Speed
wrote:



"Tough Guy no. 1265" wrote in message
news On Sat, 07 Nov 2015 20:23:54 -0000, Cursitor Doom

wrote:

On Sat, 07 Nov 2015 20:19:27 +0000, Tough Guy no. 1265 wrote:

Besides, I've never actually observed a fault where the chassis
becomes
live. The only shocks I've ever had were worn cables on a mower,
touching a switch with wet hands when outside, etc. Now if the
supply
had been isolated, I wouldn't have received a shock.

Naw, you want an RCD for that, mate.

Which wouldn't be needed if they simply removed the earth from the
neutral.

Wrong. You can still get killed with that config.

But in half the number of ways.

Wrong when its done at the substation.

Explain.

That's the reason NO ONE does it like that WORLD WIDE.

There might just be a reason why no one does it that way world wide.

The link I posted originally suggests it may be nothing more tan historic.

Its just plain wrong on that.

The real reason is that the only way it would work
is a ****ing great transformer for each house.

And remember RCDs never used to exist.

Irrelevant to what makes sense now that they do.

RCDs are a nuisance. I would never install one in my house.

You're free to be as stupid as you like. Sooner fools like you die the
better.

240 volts is not usually dangerous.

Even more pig ignorant than you usually manage.

And it's ****ing annoying when you get nuisance trips.

**** all get nuisance trips.

On 07/11/2015 23:37, Tough Guy no. 1265 wrote:
On Sat, 07 Nov 2015 22:54:34 -0000, Rod Speed
wrote:



"Tough Guy no. 1265" wrote in message
news
On Sat, 07 Nov 2015 21:46:51 -0000, Rod Speed
wrote:



"Tough Guy no. 1265" wrote in message
news On Sat, 07 Nov 2015 20:23:54 -0000, Cursitor Doom

wrote:

On Sat, 07 Nov 2015 20:19:27 +0000, Tough Guy no. 1265 wrote:

Besides, I've never actually observed a fault where the chassis
becomes
live. The only shocks I've ever had were worn cables on a mower,
touching a switch with wet hands when outside, etc. Now if the
supply
had been isolated, I wouldn't have received a shock.

Naw, you want an RCD for that, mate.

Which wouldn't be needed if they simply removed the earth from the
neutral.

Wrong. You can still get killed with that config.

But in half the number of ways.

Wrong when its done at the substation.

Explain.

There might just be a reason why no one does it that way world wide.

The link I posted originally suggests it may be nothing more tan historic.

And remember RCDs never used to exist.

Irrelevant to what makes sense now that they do.

RCDs are a nuisance. I would never install one in my house.

You're free to be as stupid as you like. Sooner fools like you die the
better.

240 volts is not usually dangerous. And it's ****ing annoying when you
get nuisance trips.

Try it on a circuit without an RCD a few times, then tell us of your
experience.

On Sat, 07 Nov 2015 20:29:41 +0000, Cursitor Doom wrote:

On Sat, 07 Nov 2015 20:20:06 +0000, A.Lee wrote:

They have transformers at 55 volt per side, so a typical fault would
only give you a 55 volt belt.

55V doesn't constitute a "belt" in my book. Can't feel anything at all
below 80V; that's the point when I first feel a slight tingle.

In dry conditions, 55vac might only give you a mild 'tingle' but on a
building site working in the rain, it's a different story, you will get a
bit of a belt (but with far less risk of electrocution than if it were a
240v contact or even 120v).

These site transformers provide a bi-phase 110v supply to the tools, the
centre tap on the secondary is connected to earth to prevent either of
the phases rising to 110v with respect to earth in the event of an
earthing fault on the opposite phase.

--
Johnny B Good

On Saturday, 7 November 2015 19:07:06 UTC, Tough Guy no. 1265 wrote:
On Sat, 07 Nov 2015 18:14:59 -0000, harry wrote:

On Saturday, 7 November 2015 16:42:25 UTC, Tough Guy no. 1265 wrote:
I looked this up, I'm asking the question at the top. The replies don't seem to be able to agree. Any sensible opinions?

http://electronics.stackexchange.com...e-mains-supply

--
It said, "Insert disk #3," but only two will fit!

It is important when electrical equipment/appliances have metal cabinets which can be earthed. Which was everything years ago.
Without an earth, ant fault to the cabinet could not be detected and would be dangerous if there were other earth faults.
Also get over certain capacitance effects.

Two faults is unlikely. One fault would of course not shock you at all. Most shocks are an exposed live to an earth, isolating the mains would remove that possibility altogether, and not change the amount of shocks between live and neutral.

--
H lp! S m b d st l ll th v w ls fr m m k yb rd!

Nearly all accidents occur when two unlikely factors coincide.

On Saturday, 7 November 2015 20:19:32 UTC, Tough Guy no. 1265 wrote:
On Sat, 07 Nov 2015 20:05:02 -0000, Fredxxx wrote:

On 07/11/2015 19:07, Tough Guy no. 1265 wrote:
On Sat, 07 Nov 2015 18:14:59 -0000, harry
wrote:

On Saturday, 7 November 2015 16:42:25 UTC, Tough Guy no. 1265 wrote:
I looked this up, I'm asking the question at the top. The replies
don't seem to be able to agree. Any sensible opinions?

http://electronics.stackexchange.com...e-mains-supply


--
It said, "Insert disk #3," but only two will fit!

It is important when electrical equipment/appliances have metal
cabinets which can be earthed. Which was everything years ago.
Without an earth, ant fault to the cabinet could not be detected and
would be dangerous if there were other earth faults.
Also get over certain capacitance effects.

Two faults is unlikely. One fault would of course not shock you at
all. Most shocks are an exposed live to an earth, isolating the mains
would remove that possibility altogether, and not change the amount of
shocks between live and neutral.

I would agree with you, but only if you can automatically detect each of
the faults and interrupt the power accordingly.

An isolation transformer might well hide some faults as well as
introducing some more and so be more dangerous in reality than the
conventional single phase supply.

But the two faults would have to be within reach of each other, eg your washing machine and your fridge both having a fault with the opposite conductor, and you touch both. So very unlikely.

Besides, I've never actually observed a fault where the chassis becomes live. The only shocks I've ever had were worn cables on a mower, touching a switch with wet hands when outside, etc. Now if the supply had been isolated, I wouldn't have received a shock.

You won't observe a fault where a chassis becomes live because it is earthed.
One of the faults could be miles away.

On Sunday, 8 November 2015 00:00:01 UTC, Fredxxx wrote:
On 07/11/2015 23:37, Tough Guy no. 1265 wrote:
On Sat, 07 Nov 2015 22:54:34 -0000, Rod Speed
wrote:



"Tough Guy no. 1265" wrote in message
news On Sat, 07 Nov 2015 21:46:51 -0000, Rod Speed
wrote:



"Tough Guy no. 1265" wrote in message
news On Sat, 07 Nov 2015 20:23:54 -0000, Cursitor Doom

wrote:

On Sat, 07 Nov 2015 20:19:27 +0000, Tough Guy no. 1265 wrote:

Besides, I've never actually observed a fault where the chassis
becomes
live. The only shocks I've ever had were worn cables on a mower,
touching a switch with wet hands when outside, etc. Now if the
supply
had been isolated, I wouldn't have received a shock.

Naw, you want an RCD for that, mate.

Which wouldn't be needed if they simply removed the earth from the
neutral.

Wrong. You can still get killed with that config.

But in half the number of ways.

Wrong when its done at the substation.

Explain.

There might just be a reason why no one does it that way world wide.

The link I posted originally suggests it may be nothing more tan historic.

And remember RCDs never used to exist.

Irrelevant to what makes sense now that they do.

RCDs are a nuisance. I would never install one in my house.

You're free to be as stupid as you like. Sooner fools like you die the
better.

240 volts is not usually dangerous. And it's ****ing annoying when you
get nuisance trips.


People have been killed with as low as 40 volts.

On Saturday, 7 November 2015 19:27:13 UTC, Tough Guy no. 1265 wrote:
On Sat, 07 Nov 2015 19:12:57 -0000, wrote:

On Saturday, November 7, 2015 at 4:42:25 PM UTC, Tough Guy no. 1265 wrote:
I looked this up, I'm asking the question at the top. The replies don't seem to be able to agree. Any sensible opinions?

http://electronics.stackexchange.com...e-mains-supply

--
It said, "Insert disk #3," but only two will fit!

Because mains is an AC system, there is no such thing as a totally isolated system. There is always some capacitance between the conductors and earth which all adds up.

Why do builders have isolating transformers then?


They are 110 volts, centre tapped to earth so there is 55 volts to earth.

On Saturday, 7 November 2015 20:20:46 UTC, Tough Guy no. 1265 wrote:
On Sat, 07 Nov 2015 20:13:05 -0000, Fredxxx wrote:

On 07/11/2015 20:01, Tough Guy no. 1265 wrote:
On Sat, 07 Nov 2015 19:38:55 -0000, Chris Hogg wrote:

On Sat, 07 Nov 2015 19:27:07 -0000, "Tough Guy no. 1265"
wrote:

On Sat, 07 Nov 2015 19:12:57 -0000,
wrote:

On Saturday, November 7, 2015 at 4:42:25 PM UTC, Tough Guy no. 1265
wrote:
I looked this up, I'm asking the question at the top. The replies
don't seem to be able to agree. Any sensible opinions?

http://electronics.stackexchange.com...e-mains-supply


--
It said, "Insert disk #3," but only two will fit!

Because mains is an AC system, there is no such thing as a totally
isolated system. There is always some capacitance between the
conductors and earth which all adds up.

Why do builders have isolating transformers then?

And electric shaver sockets in bathrooms? I would think they're just a
small version of whole-house isolation?

Perhaps it's just because it's always been done that way, and that way
is cheaper than having a beefy transformer in every garage.

The substation could isolate. Just don't clamp neutral to the ground.
4 wires come out of the secondary side of the substation transformer,
leave them away from the ground, and take them to the houses as normal.

Do you understand about 3-phase distribution?

If you don't clamp neutral to ground, what do you think will happen to
each phase voltage wrt ground?

230V is enough for me!

If isolated, no phase has any voltage with respect to ground, just like a battery sitting on your desk has no voltage with respect to ground.

Batteries are only safe because they are usually only low voltage.

On Saturday, 7 November 2015 20:31:58 UTC, Cursitor Doom wrote:
On Sat, 07 Nov 2015 20:20:06 +0000, A.Lee wrote:

They have transformers at 55 volt per side, so a typical fault would
only give you a 55 volt belt.

55V doesn't constitute a "belt" in my book. Can't feel anything at all
below 80V; that's the point when I first feel a slight tingle.

Drivel. Try the experiment stood in the bath.
Or with wet feet/hands, touching earth.

Do you mean a transformer so one side of the mains could be earthed even on
a hot chassis device?
Most test set ups tend to be this way of course, but to do this with the
whole supply to a home would need a very big transformar?
Brian

--
From the Sofa of Brian Gaff Reply address is active
Remember, if you don't like where I post
or what I say, you don't have to
read my posts! :-)
"Tough Guy no. 1265" wrote in message
news
I looked this up, I'm asking the question at the top. The replies don't
seem to be able to agree. Any sensible opinions?

http://electronics.stackexchange.com...e-mains-supply

--
It said, "Insert disk #3," but only two will fit!

Pardon?

Brian

--
From the Sofa of Brian Gaff Reply address is active
Remember, if you don't like where I post
or what I say, you don't have to
read my posts! :-)
"bm" wrote in message
eb.com...
**** snipped

On Sat, 07 Nov 2015 23:37:10 +0000, Tough Guy no. 1265 wrote:

240 volts is not usually dangerous. And it's ****ing annoying when you
get nuisance trips.

Yes, it's always a terrible nuisance when you're being electrocuted and
some device quickly shuts the power off.

On Sun, 08 Nov 2015 00:53:10 -0800, harry wrote:

You won't observe a fault where a chassis becomes live because it is
earthed.

Oh I don't know. He's probably replaced all his fuses with nails 'cos
they blew once in a while.

On Sun, 08 Nov 2015 01:01:54 -0800, harry wrote:

Drivel. Try the experiment stood in the bath.
Or with wet feet/hands, touching earth.

Why would I want to do that? Of course one's skin resistance is massively
reduced when wet, consequently raising the risk of severe shock and
electrocution. In dry conditions, however, I personally can't feel
*anything* under 80V. YMMV.

On 08/11/15 10:12, Cursitor Doom wrote:
On Sat, 07 Nov 2015 23:37:10 +0000, Tough Guy no. 1265 wrote:

240 volts is not usually dangerous. And it's ****ing annoying when you
get nuisance trips.

Yes, it's always a terrible nuisance when you're being electrocuted and
some device quickly shuts the power off.

The problem is that the requirements for RFI filtering, plus the advent
of switched mode power supplies, plus the number of them now extant in
the average household, now means there is enough capacitance between
live and earth to guarantee nuisance trips if you get a voltage spike.
And often when you don't as well.



--
the biggest threat to humanity comes from socialism, which has utterly
diverted our attention away from what really matters to our existential
survival, to indulging in navel gazing and faux moral investigations
into what the world ought to be, whilst we fail utterly to deal with
what it actually is.

In article ,
Tough Guy no. 1265 wrote:
Why do builders have isolating transformers then?

Generally, because the tools are 110v.

Going back years in TV studios, any domestic equipment or musical
instrument that needed mains power was fed via an isolating transformer.

These days, using an RCD provides the same safety requirement, and at
far less cost.

--
*The last thing I want to do is hurt you. But it's still on my list.

Dave Plowman London SW
To e-mail, change noise into sound.

Brian-Gaff wrote

Do you mean a transformer so one side of the mains could be earthed even
on a hot chassis device?
Most test set ups tend to be this way of course, but to do this with the
whole supply to a home would need a very big transformar?

He proposes to do it with the existing substation transformer
and doesn’t realise it wont work with that one, essentially
because any of the houses supplied by that substation
can earth one leg due to an earth fault.

That's the reason the builder's 110V supply is center
tapped with that center tap earthed, not fully floating.

Tough Guy no. 1265 wrote

I looked this up, I'm asking the question at the top. The replies don't
seem to be able to agree. Any sensible opinions?

http://electronics.stackexchange.com...e-mains-supply

On Sun, 08 Nov 2015 17:37:18 -0000, Rod Speed wrote:

Brian-Gaff wrote

Do you mean a transformer so one side of the mains could be earthed even
on a hot chassis device?
Most test set ups tend to be this way of course, but to do this with the
whole supply to a home would need a very big transformar?

He proposes to do it with the existing substation transformer
and doesnt realise it wont work with that one, essentially
because any of the houses supplied by that substation
can earth one leg due to an earth fault.

So instead of having it ALWAYS possible to get a shock from live, it's not only possible if there's a fault. Better, no?

That's the reason the builder's 110V supply is center
tapped with that center tap earthed, not fully floating.

I saw some builders doing roughcasting on a terrace of council houses. Instead of simply asking one of the tenants to lend them some juice, they had a great big noisy generator running all day. If I'd lived there, I would have had strong words with them and produced an extension cord.

Tough Guy no. 1265 wrote

I looked this up, I'm asking the question at the top. The replies don't
seem to be able to agree. Any sensible opinions?

http://electronics.stackexchange.com...e-mains-supply




--
Which is it, is man one of god's blunders or is god one of man's? -- Friedrich Nietzsche

On Sun, 08 Nov 2015 12:44:54 -0000, Dave Plowman (News) wrote:

In article ,
Tough Guy no. 1265 wrote:
Why do builders have isolating transformers then?

Generally, because the tools are 110v.

Going back years in TV studios, any domestic equipment or musical
instrument that needed mains power was fed via an isolating transformer.

These days, using an RCD provides the same safety requirement, and at
far less cost.

Why would a TV studio be a dangerous environment?

--
In case of exposure to lack of substance, please do not continue to refrain from stopping.

On Sun, 08 Nov 2015 11:04:06 -0000, The Natural Philosopher wrote:

On 08/11/15 10:12, Cursitor Doom wrote:
On Sat, 07 Nov 2015 23:37:10 +0000, Tough Guy no. 1265 wrote:

240 volts is not usually dangerous. And it's ****ing annoying when you
get nuisance trips.

Yes, it's always a terrible nuisance when you're being electrocuted and
some device quickly shuts the power off.

The problem is that the requirements for RFI filtering, plus the advent
of switched mode power supplies, plus the number of them now extant in
the average household, now means there is enough capacitance between
live and earth to guarantee nuisance trips if you get a voltage spike.
And often when you don't as well.

20 computers in a room where I used to work. Almost impossible to get them on without tripping the bloody thing. You had to plug in one at a time. That's plug in, not switch on.

--
What is the difference between a female jogger and a sewing machine?
A sewing machine only has one bobbin.

On Sun, 08 Nov 2015 10:12:12 -0000, Cursitor Doom wrote:

On Sat, 07 Nov 2015 23:37:10 +0000, Tough Guy no. 1265 wrote:

240 volts is not usually dangerous. And it's ****ing annoying when you
get nuisance trips.

Yes, it's always a terrible nuisance when you're being electrocuted and
some device quickly shuts the power off.

Except most trips are nuisance trips, not a danger.

--
What does a Polish woman do after she sucks a cock?
Spits out the feathers.

On Sun, 08 Nov 2015 08:53:10 -0000, harry wrote:

On Saturday, 7 November 2015 20:19:32 UTC, Tough Guy no. 1265 wrote:
On Sat, 07 Nov 2015 20:05:02 -0000, Fredxxx wrote:

On 07/11/2015 19:07, Tough Guy no. 1265 wrote:
On Sat, 07 Nov 2015 18:14:59 -0000, harry
wrote:

On Saturday, 7 November 2015 16:42:25 UTC, Tough Guy no. 1265 wrote:
I looked this up, I'm asking the question at the top. The replies
don't seem to be able to agree. Any sensible opinions?

http://electronics.stackexchange.com...e-mains-supply


--
It said, "Insert disk #3," but only two will fit!

It is important when electrical equipment/appliances have metal
cabinets which can be earthed. Which was everything years ago.
Without an earth, ant fault to the cabinet could not be detected and
would be dangerous if there were other earth faults.
Also get over certain capacitance effects.

Two faults is unlikely. One fault would of course not shock you at
all. Most shocks are an exposed live to an earth, isolating the mains
would remove that possibility altogether, and not change the amount of
shocks between live and neutral.

I would agree with you, but only if you can automatically detect each of
the faults and interrupt the power accordingly.

An isolation transformer might well hide some faults as well as
introducing some more and so be more dangerous in reality than the
conventional single phase supply.

But the two faults would have to be within reach of each other, eg your washing machine and your fridge both having a fault with the opposite conductor, and you touch both. So very unlikely.

Besides, I've never actually observed a fault where the chassis becomes live. The only shocks I've ever had were worn cables on a mower, touching a switch with wet hands when outside, etc. Now if the supply had been isolated, I wouldn't have received a shock.

You won't observe a fault where a chassis becomes live because it is earthed.
One of the faults could be miles away.

I would have known about them because a fuse would have blown, then I'd investigate the fault. I've never seen a live chassis.

--
What does Michael Jackson like about twenty-eight year olds?
The fact that there are twenty of them.

On Sun, 08 Nov 2015 08:59:34 -0000, harry wrote:

On Saturday, 7 November 2015 20:20:46 UTC, Tough Guy no. 1265 wrote:
On Sat, 07 Nov 2015 20:13:05 -0000, Fredxxx wrote:

On 07/11/2015 20:01, Tough Guy no. 1265 wrote:
On Sat, 07 Nov 2015 19:38:55 -0000, Chris Hogg wrote:

On Sat, 07 Nov 2015 19:27:07 -0000, "Tough Guy no. 1265"
wrote:

On Sat, 07 Nov 2015 19:12:57 -0000,
wrote:

On Saturday, November 7, 2015 at 4:42:25 PM UTC, Tough Guy no. 1265
wrote:
I looked this up, I'm asking the question at the top. The replies
don't seem to be able to agree. Any sensible opinions?

http://electronics.stackexchange.com...e-mains-supply


--
It said, "Insert disk #3," but only two will fit!

Because mains is an AC system, there is no such thing as a totally
isolated system. There is always some capacitance between the
conductors and earth which all adds up.

Why do builders have isolating transformers then?

And electric shaver sockets in bathrooms? I would think they're just a
small version of whole-house isolation?

Perhaps it's just because it's always been done that way, and that way
is cheaper than having a beefy transformer in every garage.

The substation could isolate. Just don't clamp neutral to the ground.
4 wires come out of the secondary side of the substation transformer,
leave them away from the ground, and take them to the houses as normal.

Do you understand about 3-phase distribution?

If you don't clamp neutral to ground, what do you think will happen to
each phase voltage wrt ground?

230V is enough for me!

If isolated, no phase has any voltage with respect to ground, just like a battery sitting on your desk has no voltage with respect to ground.

Batteries are only safe because they are usually only low voltage.

Irrelevant to the fact that they have no voltage WRT ground.

--
What does Michael Jackson like about twenty-eight year olds?
The fact that there are twenty of them.

On Sun, 08 Nov 2015 08:57:57 -0000, harry wrote:

On Saturday, 7 November 2015 19:27:13 UTC, Tough Guy no. 1265 wrote:
On Sat, 07 Nov 2015 19:12:57 -0000, wrote:

On Saturday, November 7, 2015 at 4:42:25 PM UTC, Tough Guy no. 1265 wrote:
I looked this up, I'm asking the question at the top. The replies don't seem to be able to agree. Any sensible opinions?

http://electronics.stackexchange.com...e-mains-supply

--
It said, "Insert disk #3," but only two will fit!

Because mains is an AC system, there is no such thing as a totally isolated system. There is always some capacitance between the conductors and earth which all adds up.

Why do builders have isolating transformers then?


They are 110 volts, centre tapped to earth so there is 55 volts to earth.

Then we could have centre tapped 240V, like the yanks do.

--
Q: If you have a mothball in one hand and another mothball in the other hand, what would you have?
A: The undivided attention of a very large moth!

On Sun, 08 Nov 2015 00:00:00 -0000, Fredxxx wrote:

On 07/11/2015 23:37, Tough Guy no. 1265 wrote:
On Sat, 07 Nov 2015 22:54:34 -0000, Rod Speed
wrote:



"Tough Guy no. 1265" wrote in message
news On Sat, 07 Nov 2015 21:46:51 -0000, Rod Speed
wrote:



"Tough Guy no. 1265" wrote in message
news On Sat, 07 Nov 2015 20:23:54 -0000, Cursitor Doom

wrote:

On Sat, 07 Nov 2015 20:19:27 +0000, Tough Guy no. 1265 wrote:

Besides, I've never actually observed a fault where the chassis
becomes
live. The only shocks I've ever had were worn cables on a mower,
touching a switch with wet hands when outside, etc. Now if the
supply
had been isolated, I wouldn't have received a shock.

Naw, you want an RCD for that, mate.

Which wouldn't be needed if they simply removed the earth from the
neutral.

Wrong. You can still get killed with that config.

But in half the number of ways.

Wrong when its done at the substation.

Explain.

There might just be a reason why no one does it that way world wide.

The link I posted originally suggests it may be nothing more tan historic.

And remember RCDs never used to exist.

Irrelevant to what makes sense now that they do.

RCDs are a nuisance. I would never install one in my house.

You're free to be as stupid as you like. Sooner fools like you die the
better.

240 volts is not usually dangerous. And it's ****ing annoying when you
get nuisance trips.

Try it on a circuit without an RCD a few times, then tell us of your
experience.

Try what on a circuit without an RCD? My house has no RCD, it has a fusebox, the traditional kind with fusewire.

--
Why is the front of an aeroplane called a cockpit?
If you have female pilots do you call it a pussypit?

On Sun, 08 Nov 2015 08:55:20 -0000, harry wrote:

On Sunday, 8 November 2015 00:00:01 UTC, Fredxxx wrote:
On 07/11/2015 23:37, Tough Guy no. 1265 wrote:
On Sat, 07 Nov 2015 22:54:34 -0000, Rod Speed
wrote:



"Tough Guy no. 1265" wrote in message
news On Sat, 07 Nov 2015 21:46:51 -0000, Rod Speed
wrote:



"Tough Guy no. 1265" wrote in message
news On Sat, 07 Nov 2015 20:23:54 -0000, Cursitor Doom

wrote:

On Sat, 07 Nov 2015 20:19:27 +0000, Tough Guy no. 1265 wrote:

Besides, I've never actually observed a fault where the chassis
becomes
live. The only shocks I've ever had were worn cables on a mower,
touching a switch with wet hands when outside, etc. Now if the
supply
had been isolated, I wouldn't have received a shock.

Naw, you want an RCD for that, mate.

Which wouldn't be needed if they simply removed the earth from the
neutral.

Wrong. You can still get killed with that config.

But in half the number of ways.

Wrong when its done at the substation.

Explain.

There might just be a reason why no one does it that way world wide.

The link I posted originally suggests it may be nothing more tan historic.

And remember RCDs never used to exist.

Irrelevant to what makes sense now that they do.

RCDs are a nuisance. I would never install one in my house.

You're free to be as stupid as you like. Sooner fools like you die the
better.

240 volts is not usually dangerous. And it's ****ing annoying when you
get nuisance trips.


People have been killed with as low as 40 volts.

Yeah right, I suppose you believe that story about a 9V PP3 in a multimeter killing an army guy too.

--
My wife and I were happy for twenty years. Then we met.

On Sun, 08 Nov 2015 08:51:24 -0000, harry wrote:

On Saturday, 7 November 2015 19:07:06 UTC, Tough Guy no. 1265 wrote:
On Sat, 07 Nov 2015 18:14:59 -0000, harry wrote:

On Saturday, 7 November 2015 16:42:25 UTC, Tough Guy no. 1265 wrote:
I looked this up, I'm asking the question at the top. The replies don't seem to be able to agree. Any sensible opinions?

http://electronics.stackexchange.com...e-mains-supply

--
It said, "Insert disk #3," but only two will fit!

It is important when electrical equipment/appliances have metal cabinets which can be earthed. Which was everything years ago.
Without an earth, ant fault to the cabinet could not be detected and would be dangerous if there were other earth faults.
Also get over certain capacitance effects.

Two faults is unlikely. One fault would of course not shock you at all. Most shocks are an exposed live to an earth, isolating the mains would remove that possibility altogether, and not change the amount of shocks between live and neutral.

--
H lp! S m b d st l ll th v w ls fr m m k yb rd!

Nearly all accidents occur when two unlikely factors coincide.

But it's very unlikely. Funny how double sockets are rated at 20A. The chances of two 13A devices being plugged in is low.....

--
All religions are part of Operation Mind****: http://en.wikipedia.org/wiki/Operation_Mind****

"Tough Guy no. 1265" wrote in message
news
On Sat, 07 Nov 2015 16:50:11 -0000, ARW
wrote:

"Tough Guy no. 1265" wrote in message
news
I looked this up, I'm asking the question at the top. The replies don't
seem to be able to agree. Any sensible opinions?

http://electronics.stackexchange.com...e-mains-supply

Not from me.

You don't have a sensible opinion?!? :-)


Just the one. Ban women drivers.

--
Adam

On Sun, 08 Nov 2015 17:56:59 -0000, ARW wrote:

"Tough Guy no. 1265" wrote in message
news
On Sat, 07 Nov 2015 16:50:11 -0000, ARW
wrote:

"Tough Guy no. 1265" wrote in message
news I looked this up, I'm asking the question at the top. The replies don't
seem to be able to agree. Any sensible opinions?

http://electronics.stackexchange.com...e-mains-supply

Not from me.

You don't have a sensible opinion?!? :-)

Just the one. Ban women drivers.

You will get complete agreement from me on that. They have slow reactions and no spatial awareness.

--
The microwave was invented after a researcher walked by a radar
tube and a chocolate bar melted in his pocket.

Tough Guy no. 1265 wrote
Rod Speed wrote
Brian-Gaff wrote
Tough Guy no. 1265 wrote

I looked this up, I'm asking the question at the top. The replies
don't seem to be able to agree. Any sensible opinions?

http://electronics.stackexchange.com...e-mains-supply

Do you mean a transformer so one side of the mains could be earthed even
on a hot chassis device?

Most test set ups tend to be this way of course, but to do this with
the whole supply to a home would need a very big transformar?

He proposes to do it with the existing substation transformer
and doesnt realise it wont work with that one, essentially
because any of the houses supplied by that substation
can earth one leg due to an earth fault.

So instead of having it ALWAYS possible to get a shock from live,

That is a lie with the current approach with earthed metal body
of the appliance, double insulated appliances, RCDs etc.

it's not only possible if there's a fault. Better, no?

Nope, MUCH worse when there is no way to even detect
that fault, let alone feasible to shut all the houses on that
substation down every time there is an earth fault detected
even if it was possible to detect that fault reliably.

That's the reason the builder's 110V supply is center
tapped with that center tap earthed, not fully floating.

I saw some builders doing roughcasting on a terrace of council houses.
Instead of simply asking one of the tenants to lend them some juice, they
had a great big noisy generator running all day. If I'd lived there, I
would have had strong words with them and produced an extension cord.

The extension cord wouldn't even come
close to providing the current they needed.

"Tough Guy no. 1265" wrote in message
news
On Sun, 08 Nov 2015 12:44:54 -0000, Dave Plowman (News)
wrote:

In article ,
Tough Guy no. 1265 wrote:
Why do builders have isolating transformers then?

Generally, because the tools are 110v.

Going back years in TV studios, any domestic equipment or musical
instrument that needed mains power was fed via an isolating transformer.

These days, using an RCD provides the same safety requirement, and at
far less cost.

Why would a TV studio be a dangerous environment?

It wasn't done that way because of the danger.

"Tough Guy no. 1265" wrote in message
news
On Sun, 08 Nov 2015 08:57:57 -0000, harry
wrote:

On Saturday, 7 November 2015 19:27:13 UTC, Tough Guy no. 1265 wrote:
On Sat, 07 Nov 2015 19:12:57 -0000,
wrote:

On Saturday, November 7, 2015 at 4:42:25 PM UTC, Tough Guy no. 1265
wrote:
I looked this up, I'm asking the question at the top. The replies
don't seem to be able to agree. Any sensible opinions?

http://electronics.stackexchange.com...e-mains-supply

--
It said, "Insert disk #3," but only two will fit!

Because mains is an AC system, there is no such thing as a totally
isolated system. There is always some capacitance between the
conductors and earth which all adds up.

Why do builders have isolating transformers then?


They are 110 volts, centre tapped to earth so there is 55 volts to earth.

Then we could have centre tapped 240V, like the yanks do.

They don't earth their center tap.

"Tough Guy no. 1265" wrote in message
news
On Sun, 08 Nov 2015 08:51:24 -0000, harry
wrote:

On Saturday, 7 November 2015 19:07:06 UTC, Tough Guy no. 1265 wrote:
On Sat, 07 Nov 2015 18:14:59 -0000, harry
wrote:

On Saturday, 7 November 2015 16:42:25 UTC, Tough Guy no. 1265 wrote:
I looked this up, I'm asking the question at the top. The replies
don't seem to be able to agree. Any sensible opinions?

http://electronics.stackexchange.com...e-mains-supply

--
It said, "Insert disk #3," but only two will fit!

It is important when electrical equipment/appliances have metal
cabinets which can be earthed. Which was everything years ago.
Without an earth, ant fault to the cabinet could not be detected and
would be dangerous if there were other earth faults.
Also get over certain capacitance effects.

Two faults is unlikely. One fault would of course not shock you at all.
Most shocks are an exposed live to an earth, isolating the mains would
remove that possibility altogether, and not change the amount of shocks
between live and neutral.

--
H lp! S m b d st l ll th v w ls fr m m k yb rd!

Nearly all accidents occur when two unlikely factors coincide.

But it's very unlikely.

Accidents happen anyway, every single day in fact in large numbers.

Funny how double sockets are rated at 20A. The chances of two 13A devices
being plugged in is low.....

Not anymore with so many high powered devices like
convection ovens, electric jugs, heaters, microwaves etc etc etc.