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Strange not-quite-240 high-voltage smoke problem... short? circuit breaker?



 
 
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  #1  
Old February 17th 04, 04:33 PM
Kent Monroe
external usenet poster
 
Posts: n/a
Default Strange not-quite-240 high-voltage smoke problem... short? circuit breaker?

Hi all,

I have a puzzler and need help. I'm getting some very strange high
voltages, high neutral-ground voltages, and smoke! I'm not sure if
I've got a bad breaker, or a wall short, mis-wiring, or a broken
ground, or ???


My sister-in-law's condo has a 2-pole 20Amp Sylvania circuit breaker
circuit which provides two different phases of 120V to the following:

1st 120V pole: Garbage disposal, powered on by a wall switch.
2nd 120V pole: Dishwasher

One of the above also powers a regular wall socket but I didn't check
which pole (probably the 1st). The wiring for both poles is pretty much
behind the sink, likely routed next to each other from the main box.

The disposal and dishwasher have worked fine in the past, but all
of a sudden, both stopped working. As the dishwasher was old and had a
broken latch too, she decided to buy a new dishwasher, and nice brother-
in-law that I am, I agreed to install it for her for free (tight budget).

I noticed something strange with the voltage meter from the start,
which is that I still had some residual voltage on either circuit until
I turned BOTH circuit breakers off. For example:

With nothing connected to either circuit (which turns out to matter but
shouldn't), I measured voltages of the wires at the appliances:

1st pole (disposal) breaker OFF, 2nd pole (dishwasher) breaker ON:
1st pole: black-neutral ~12V ; black-ground ~13V ; ground-neutral ~1V
2nd pole: normal 120V (black-neutral ~121V ; black-ground 123V)

1st pole breaker ON, 2nd pole breaker OFF:
1st pole: normal 120V (black-neutral ~121V ; black-ground 123V)
2nd pole: black-neutral ~15V ; black-ground ~16V ; ground-neutral ~2V


So then, I wired up the dishwasher, turned on the 2nd pole and... nothing.
The dishwasher didn't work. It didn't matter that I had just measured 120V
before connecting it.

Next I plugged in the disposal, turned on the 1st pole, then the wall switch
and then... the disposal ran like a bat-out-of-hell! Then SMOKE appeared
at both the disposal, AND from the bottom of the dishwasher (which wasn't
even running) !!!

Fortunately, when I tested both the disposal and the dishwasher on a different
wall-plug circuit, both still worked fine. Nothing smoked, and the disposal
motor was clearly running normal, slower than before.


One more test: With the dishwasher connected (2nd pole circuit) I measured
voltages at the (1st pole) disposal wall plug (without the disposal
connected, since that makes smoke), and I got the following abnormal
voltages:

With both 1st pole and 2nd pole breakers ON:

2nd pole: black-neutral 206V!!! ; black-ground 123V ; neutral-ground 85V!!!


With the 1st pole breaker ON, and 2nd pole breaker OFF, it seems "normal":

2nd pole: black-neutral 121V ; black-ground 123V ; neutral-ground 3V


With the 1st pole breaker OFF, and the 2nd pole breaker ON, it's weird:

2nd pole: black-neutral 47V! ; black-ground 33V! ; neutral-ground 83V!



Oh, and by the way, during the many measurements of voltages, I got careless
and managed to arc the wires at both circuits with my voltmeter probe
(which lost it's nice brand new pointy tip :-O ). It neither case
did either 20A breaker trip. Maybe it didn't exceed 20A, but I was a
bit suprised it didn't trip the breaker).


What the heck is going on? How come the dishwasher won't work with JUST
it's own breaker turned on, and with 121V no-load voltage measured?

How come I get smoke and strange high-voltages with both appliances
connected and both breakers on, as soon as I turn on the disposal?


Should I just replace the breaker first, and if that doesn't fix it,
call an electrician? Or is replacing the breaker a waste of time
and money?


Thanks in advance for any help,
Kent
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  #2  
Old February 17th 04, 04:46 PM
m Ransley
external usenet poster
 
Posts: n/a
Default Strange not-quite-240 high-voltage smoke problem... short?circ...

Either your a troll or not very smart, call a pro before anything else
goes wrong, you probably damaged more than you realise

  #3  
Old February 17th 04, 04:53 PM
gabriel
external usenet poster
 
Posts: n/a
Default Strange not-quite-240 high-voltage smoke problem... short? circuit breaker?

Kent Monroe wrote:

My sister-in-law's condo has a 2-pole 20Amp Sylvania circuit breaker
circuit which provides two different phases of 120V to the following:


Wouldn't you want to replace this with two separate one-pole breakers?

--
gabriel
  #4  
Old February 17th 04, 04:54 PM
John Grabowski
external usenet poster
 
Posts: n/a
Default Strange not-quite-240 high-voltage smoke problem... short? circuit breaker?

It seems as though you have a shared neutral which you failed to connect
properly, thereby sending 220 volts through the appliances. This is the
down-side of using a 2 pole breaker with a shared neutral to power 120 volt
equipment.

Stop using your voltmeter. Your readings are normal and confusing you.
Your meter is picking up voltage that is passing through each appliance.
Check your neutral connection by beginning at the panel and finish where it
terminates at each appliance.

If it was my house, I would run a separate line and get those 120 volt
circuits off of a 2 pole breaker.


John Grabowski
http://www.mrelectrician.tv



"Kent Monroe" wrote in message
om...
Hi all,

I have a puzzler and need help. I'm getting some very strange high
voltages, high neutral-ground voltages, and smoke! I'm not sure if
I've got a bad breaker, or a wall short, mis-wiring, or a broken
ground, or ???


My sister-in-law's condo has a 2-pole 20Amp Sylvania circuit breaker
circuit which provides two different phases of 120V to the following:

1st 120V pole: Garbage disposal, powered on by a wall switch.
2nd 120V pole: Dishwasher

One of the above also powers a regular wall socket but I didn't check
which pole (probably the 1st). The wiring for both poles is pretty much
behind the sink, likely routed next to each other from the main box.

The disposal and dishwasher have worked fine in the past, but all
of a sudden, both stopped working. As the dishwasher was old and had a
broken latch too, she decided to buy a new dishwasher, and nice brother-
in-law that I am, I agreed to install it for her for free (tight budget).

I noticed something strange with the voltage meter from the start,
which is that I still had some residual voltage on either circuit until
I turned BOTH circuit breakers off. For example:

With nothing connected to either circuit (which turns out to matter but
shouldn't), I measured voltages of the wires at the appliances:

1st pole (disposal) breaker OFF, 2nd pole (dishwasher) breaker ON:
1st pole: black-neutral ~12V ; black-ground ~13V ; ground-neutral

~1V
2nd pole: normal 120V (black-neutral ~121V ; black-ground 123V)

1st pole breaker ON, 2nd pole breaker OFF:
1st pole: normal 120V (black-neutral ~121V ; black-ground 123V)
2nd pole: black-neutral ~15V ; black-ground ~16V ; ground-neutral

~2V


So then, I wired up the dishwasher, turned on the 2nd pole and... nothing.
The dishwasher didn't work. It didn't matter that I had just measured

120V
before connecting it.

Next I plugged in the disposal, turned on the 1st pole, then the wall

switch
and then... the disposal ran like a bat-out-of-hell! Then SMOKE

appeared
at both the disposal, AND from the bottom of the dishwasher (which wasn't
even running) !!!

Fortunately, when I tested both the disposal and the dishwasher on a

different
wall-plug circuit, both still worked fine. Nothing smoked, and the

disposal
motor was clearly running normal, slower than before.


One more test: With the dishwasher connected (2nd pole circuit) I

measured
voltages at the (1st pole) disposal wall plug (without the disposal
connected, since that makes smoke), and I got the following abnormal
voltages:

With both 1st pole and 2nd pole breakers ON:

2nd pole: black-neutral 206V!!! ; black-ground 123V ; neutral-ground

85V!!!


With the 1st pole breaker ON, and 2nd pole breaker OFF, it seems "normal":

2nd pole: black-neutral 121V ; black-ground 123V ; neutral-ground 3V


With the 1st pole breaker OFF, and the 2nd pole breaker ON, it's weird:

2nd pole: black-neutral 47V! ; black-ground 33V! ; neutral-ground 83V!



Oh, and by the way, during the many measurements of voltages, I got

careless
and managed to arc the wires at both circuits with my voltmeter probe
(which lost it's nice brand new pointy tip :-O ). It neither case
did either 20A breaker trip. Maybe it didn't exceed 20A, but I was a
bit suprised it didn't trip the breaker).


What the heck is going on? How come the dishwasher won't work with JUST
it's own breaker turned on, and with 121V no-load voltage measured?

How come I get smoke and strange high-voltages with both appliances
connected and both breakers on, as soon as I turn on the disposal?


Should I just replace the breaker first, and if that doesn't fix it,
call an electrician? Or is replacing the breaker a waste of time
and money?


Thanks in advance for any help,
Kent



  #5  
Old February 17th 04, 05:07 PM
gabriel
external usenet poster
 
Posts: n/a
Default Strange not-quite-240 high-voltage smoke problem... short? circ...

m Ransley wrote:

Either your a troll or not very smart, call a pro before anything else
goes wrong, you probably damaged more than you realise


Cammon play nice. If you expect people who ask questions to know the
answer beforehand, you're in the wrong place.

--
gabriel
  #6  
Old February 17th 04, 07:19 PM
Joseph Meehan
external usenet poster
 
Posts: n/a
Default Strange not-quite-240 high-voltage smoke problem... short? circuit breaker?

Kent Monroe wrote:
Hi all,


Just a couple of suggestions.

It sounds like that should be two independent breakers.

You should make sure you do not have a floating neutral.

Don't try to use a modern digital meter to measure the voltage. It will
respond to stray current coming from lines running close to the one you are
measuring. Get an old meter analog meter than has a low internal resistance
to bleed off this voltage to get an meaningful measurement.

--
Joseph E. Meehan

26 + 6 = 1 It's Irish Math



  #7  
Old February 17th 04, 07:19 PM
Kent Monroe
external usenet poster
 
Posts: n/a
Default Strange not-quite-240 high-voltage smoke problem... short? circuit breaker?


"John Grabowski" wrote in message
...
It seems as though you have a shared neutral which you failed to connect
properly, thereby sending 220 volts through the appliances. This is the
down-side of using a 2 pole breaker with a shared neutral to power 120

volt
equipment.

Stop using your voltmeter. Your readings are normal and confusing you.
Your meter is picking up voltage that is passing through each appliance.
Check your neutral connection by beginning at the panel and finish where

it
terminates at each appliance.

If it was my house, I would run a separate line and get those 120 volt
circuits off of a 2 pole breaker.


John Grabowski
http://www.mrelectrician.tv



Hi John,

Thanks for advice.

Regards to the "2 pole" breaker... I'm just reading the extraordinarily
small print off
the breaker. It's inside a "Sylvania breaker box 390-205-09", but I can't
find any reference
to Sylvania breakers. To me, the breaker looks like the pictures of the
Zinsco type R38,
or maybe RC38 (but there's no bar between them).

This is a thin double 20A breaker.
Small type on the breaker: 2 pole, issue # LK-4137
120/240 VAC type R38 (or it could be A30, A38, R30, cause damn... it's small
print)
E16248 SA LR17830
It's 3/4" thick for the 2 switches, and 4-5/8" wide.


Is it possible to replace this 2-pole breaker with two single-pole 20A
breakers, as
another poster (gabriel, thks) suggested? Can I do this without rewiring?

My sister-in-law's place is a condo, but think "apartment" because it's
surrounded above
and on 2 sides by other units. She says nobody has done any electrical
work in her
apartment that could explain this recent failure. Routing new wires would
involve tearing
into walls, and major work which I'd really like to avoid, if possible (and
she can't afford).

I didn't change any wires in the walls or anything, and hooking up the
dishwasher is very
simple. It seems unlikely that the previously working circuits were
mis-wired, shooting
220 voltage though the original appliances without an immediate failure...

Therefore, something in the current wiring failed. From what you say, it
sounds like the
"neutral" is a common neutral for this 2-pole breaker, and I should be
looking at whether
that neutral is still connected between the breaker and each of the
appliance neutrals.

You said:
Check your neutral connection by beginning at the panel and finish where

it
terminates at each appliance.


Can you please forgive my ignorance, and suggest how? Should I turn off the
house power,
clip on a 20 foot wire to the breaker neutral, and do a continuity/resistor
test to the neutrals of
the disposal and dishwasher in the kitchen? Or is there something else you
had in mind?

Is it still possible it's just the breaker which has failed, or does that
sound unlikely from
what I've described?


Thanks again,
Kent




  #8  
Old February 17th 04, 07:36 PM
gabriel
external usenet poster
 
Posts: n/a
Default Strange not-quite-240 high-voltage smoke problem... short? circuit breaker?

Kent Monroe wrote:

This is a thin double 20A breaker.
Small type on the breaker: 2 pole, issue # LK-4137
120/240 VAC type R38 (or it could be A30, A38, R30, cause damn... it's
small print)
E16248 SA LR17830
It's 3/4" thick for the 2 switches, and 4-5/8" wide.


Huh? Is it a breaker with two 20A switches that fit into one slot of the
breaker box? The switches are _not_ tied together, and they do not
trip/turn off and on at the same time, right? This has to be the case if
the breaker is 3/4" thick with two switches on it...

If so, then you do _not_ have a 2-pole breaker (which is normally used
for 220V circuits). You have a compound single-pole breaker.

Anyway, if this is the case, we have been addressing the problem totally
wrong (so throw out _everything_ that's been said), so please confirm.

--
gabriel
  #9  
Old February 17th 04, 08:09 PM
Kent Monroe
external usenet poster
 
Posts: n/a
Default Strange not-quite-240 high-voltage smoke problem... short? circuit breaker?


"gabriel" wrote in message
ervers.com...
Kent Monroe wrote:

This is a thin double 20A breaker.
Small type on the breaker: 2 pole, issue # LK-4137
120/240 VAC type R38 (or it could be A30, A38, R30, cause damn... it's
small print)
E16248 SA LR17830
It's 3/4" thick for the 2 switches, and 4-5/8" wide.


Huh? Is it a breaker with two 20A switches that fit into one slot of the
breaker box? The switches are _not_ tied together, and they do not
trip/turn off and on at the same time, right? This has to be the case if
the breaker is 3/4" thick with two switches on it...

If so, then you do _not_ have a 2-pole breaker (which is normally used
for 220V circuits). You have a compound single-pole breaker.


I confirm that they are _not_ tied together. However, I don't think the
3/4"
size dictates which type it is. For example, see:
http://www.breakerbroker.com/zintwopoltwi.html which says:
Zinsco Two Pole Twin, Separately Switched, R38, vs.
Zinsco Two Pole Twin, (joined), RC38

I'm guessing I have the "R38", or something similar, maybe not even Zinsco
because
I can't see a brand name and will bring a magnifying glass with me next
visit.

Anyway, if this is the case, we have been addressing the problem totally
wrong (so throw out _everything_ that's been said), so please confirm.

--
gabriel


So sorry if I mislead you, but the breaker says "2 pole" so I just repeated
it here.

I'm going to look for a bad neutral, but as my last post says, I'd
appreciate any help how
to go about it. And, I'm interested to know if I can replace the breakers
easily with
some other (better) compatible model, and how to tell...

You guys are being a big help, thanks!
Kent


  #10  
Old February 18th 04, 01:35 AM
John Grabowski
external usenet poster
 
Posts: n/a
Default Strange not-quite-240 high-voltage smoke problem... short? circuit breaker?

Open up the circuit breaker box. Tighten down all of the screws terminating
neutral conductors on the neutral bar. After that open up every junction
box, outlet, switch, and luminaire on those two circuits and confirm that
the neutrals are spliced together tightly. Next go to the affected
appliances and make sure that the neutral is tightly connected to the
receptacles.

You can check the circuits with a pigtail socket and a light bulb or a lamp.
Turn on one circuit and plug the light in. If it lights dim or not at all,
you still have a problem. If it lights normal, the neutral and hot are
connected. Do the same with the other breaker. Next, turn them both on and
plug the light in. If it burns exceptionally bright or burns out
immediately, you still have a problem.

I'm not sure who manufactures Zinsco type circuit breakers these days. I
think Sylvania was at one time, but I seem to recall that Challenger was now
making them. In any case you should be able to buy Zinsco circuit breakers
at an electrical supply house. Changing the circuit breaker from a 2 pole
to two single pole breakers will NOT get rid of the problem if it is indeed
a broken neutral, but it is a good idea and worth doing unless it is a code
violation in your locality.

If the circuit breaker failed, you might not have any power on those
circuits. What I don't understand is why a 2 pole breaker was used for two
120 volt circuits? Is this condo located in the United States? How old is
the building? Older wiring can contain many loose connections. It is
possible that just by replacing an appliance, something that was loose
before has now separated completely. You did mention in your original post
that both appliances stopped working which prodded the purchase of a new
dishwasher. Obviously there was a problem before the new dishwasher was
installed.





"Kent Monroe" wrote in message
...

"John Grabowski" wrote in message
...
It seems as though you have a shared neutral which you failed to connect
properly, thereby sending 220 volts through the appliances. This is the
down-side of using a 2 pole breaker with a shared neutral to power 120

volt
equipment.

Stop using your voltmeter. Your readings are normal and confusing you.
Your meter is picking up voltage that is passing through each appliance.
Check your neutral connection by beginning at the panel and finish where

it
terminates at each appliance.

If it was my house, I would run a separate line and get those 120 volt
circuits off of a 2 pole breaker.


John Grabowski
http://www.mrelectrician.tv



Hi John,

Thanks for advice.

Regards to the "2 pole" breaker... I'm just reading the extraordinarily
small print off
the breaker. It's inside a "Sylvania breaker box 390-205-09", but I can't
find any reference
to Sylvania breakers. To me, the breaker looks like the pictures of the
Zinsco type R38,
or maybe RC38 (but there's no bar between them).

This is a thin double 20A breaker.
Small type on the breaker: 2 pole, issue # LK-4137
120/240 VAC type R38 (or it could be A30, A38, R30, cause damn... it's

small
print)
E16248 SA LR17830
It's 3/4" thick for the 2 switches, and 4-5/8" wide.


Is it possible to replace this 2-pole breaker with two single-pole 20A
breakers, as
another poster (gabriel, thks) suggested? Can I do this without

rewiring?

My sister-in-law's place is a condo, but think "apartment" because it's
surrounded above
and on 2 sides by other units. She says nobody has done any electrical
work in her
apartment that could explain this recent failure. Routing new wires

would
involve tearing
into walls, and major work which I'd really like to avoid, if possible

(and
she can't afford).

I didn't change any wires in the walls or anything, and hooking up the
dishwasher is very
simple. It seems unlikely that the previously working circuits were
mis-wired, shooting
220 voltage though the original appliances without an immediate failure...

Therefore, something in the current wiring failed. From what you say, it
sounds like the
"neutral" is a common neutral for this 2-pole breaker, and I should be
looking at whether
that neutral is still connected between the breaker and each of the
appliance neutrals.

You said:
Check your neutral connection by beginning at the panel and finish where

it
terminates at each appliance.


Can you please forgive my ignorance, and suggest how? Should I turn off

the
house power,
clip on a 20 foot wire to the breaker neutral, and do a

continuity/resistor
test to the neutrals of
the disposal and dishwasher in the kitchen? Or is there something else

you
had in mind?

Is it still possible it's just the breaker which has failed, or does that
sound unlikely from
what I've described?


Thanks again,
Kent






 




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