Circuit Breaker Panel Question

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3 wires coming into panel.
1 wire to ground.
2 other wires have 240 volts between them.
Each wire is connected to a 100 Amp breaker that is ganged to another.
Where do these wires connect to when the breaker is ON?
IOW If there is 240 VAC between these 2 wires they can't connect to the same strip, can they?
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Don't know what you are talking about or asking. If you don't know how to describe a simple setup, possibly you should not be touching anything.

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Each wire goes to one side at 120 volts. The ground is common.
If you don't know about this, I'd advise two things. 1. Don't touch anything yet 2. Get a basic electricity book
There is nothing magical about electricity in the home, but the learning curve can be deadly so don't overstep your skill level.
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wrote:

A 2 pole breaker catches both incoming phases. They are staggered on every other stab.
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The power coming in is AC That is alternating current. The ground wire and two hot wires. Each "hot" wire has current that changes 60 times a second (60 cycle) it does not stay one all the time it increases the voltage from ground plus then decreases to negative Each of the two wires are opposite so when one is positive the other is negative. That means that the difference in voltage between either wire and neutral (ground) is 120V, but one is plus 120V and the other minus 120V. The difference between the two hot wires is 240V
As it all works out if all your power is on one phase (one of the hot wires) then all the current travels between that wire and the neutral (ground). If the power is evenly split then all the current is between the two hot wires and nothing is going through the neutral (ground). A 240 volt load does not even need to be connected to the neutral (ground).

--
Joseph Meehan

Dia \'s Muire duit
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It's called buss. There are two separate busses, one for each leg. When your main breaker is "on" the current passes to each of the two busses and the circuit breakers are snapped onto this buss to send the electricity to the individual loads

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BoyntonStu wrote:

Your 100A breaker takes 4 spaces. But no they can't - each incoming wire connects to only one of the panel busses even though each half of the breaker covers both busses. The breaker might actually use connection to only 2 of the spaces or if it might use all 4 but stager the connection inside the breaker.
--
bud--

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Bud,
OK One bus must be longer in length than the other in order for the top part to reach over the shorter bus and contact the 2nd breaker output.
An electrician found an error in my breaker box and I was curious.
He measured 240 VAC between a black wire and a white wire.
Someone had connected the white wire to the panel neutral side of a GFCI breaker? Duh!
I could not understand how 240 VAC could exist.
He simply grounded the white wire everything was dandy.
Do you understand the situation?
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...

When wires are running close to each other and they are not part of the circuit, they can pick up power from the powered circuit, just like a transformer. The voltage is high but it is almost a static charge and is very easily drained off. In the old days the analog meters would drain this current off so it would record 0 Volts. but modern digital meters are so sensitive and have such high internal resistance that they don't do that and they can measure this voltage. I suspect that is what the electrician found and why he grounded it. The neutral should be at ground.
--
Joseph Meehan

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I'm not understanding you. On some panels, one leg of buss would be longer to reach a horizontally installed main breaker. A 120 volt GFCI breaker has a white wire on it that gets installed on the neutral buss.
wrote:

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Yes, it had the 20 volt GFCI breaker with a white wire on it installed on the neutral buss.
The other white wire from the black/white pair, was initially connected to the neutral of the GFCI.
When it was removed, it measured 240 VAC to the black of another circuit breaker output.
That was the surprise and confusion.
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Obviously a typo -- but what digit is missing? Was that supposed to be 120, or 240?

On a 120V GFCI breaker, that's where it's *supposed* to be connected.

Not surprising at all if you stop and think about it. Disconnect (carefully!!) the neutral wire for any circuit from the bus bar. Turn on some load on that circuit (e.g. a light bulb). Then measure the voltage between that neutral wire and the terminal of an adjacent circuit breaker (which in most panels will be on the opposite leg of the service). 240VAC is exactly what you should see.
--
Regards,
Doug Miller (alphageek at milmac dot com)
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On Dec 14, 8:16 am, snipped-for-privacy@milmac.com (Doug Miller) wrote:

Yes 240 VAC. (typo)
"Not surprising at all if you stop and think about it.
3 wires coming into panel.
1 is neutral wired to ground.
There is 240VAC between the 2 others and each is wired to a bus.
We are examining the left (odd) side column of breakers; 13 and 15.
Question 1. Are 13 and 15 on the same leg?
Question 2. What should the black of 15 measure to a lifted white wire?
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Now wait a minute. Above, you referred to a "black/white pair". Here, you're talking about three wires. Which is it?

Do you mean they are bringing power *into* the panel? If so, then what do they have to do with the GFCI breaker in the panel?

To a bus? Not to a breaker?

No. Not in most panels, anyway.

Impossible to answer, without knowing what type of circuit that white wire is part of, and what breaker(s) the other wire(s) in the circuit is/are connected to.
--
Regards,
Doug Miller (alphageek at milmac dot com)
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Gentlemen re-start your engines!
3 wires from the outside come inside to the breaker box.
A 100 AMP double breaker labeled "MAIN" receives the 2 hot wires.
The neutral is wired to ground.
The output of the 2 MAIN breakers (when switched ON) goes to 2 vertical busses.
We are examining the left (odd) side column of breakers; 13 and 15.
Question 1. Are 13 and 15 on the same leg? (I assume so)
Question 2. What should the black of 15 measure to a lifted white wire?
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Why do you assume that? The probability is very high that they are *not*. The typical arrangement is for the stabs to alternate legs vertically. That is, the top stab in each column will be on leg A, the second stab in each column on leg B, the third on leg A, and so on -- so with the left column designated as 1, 3, 5, ... then 1 and 2 are on leg A, 3 and 4 on B, 4 and 5 on A, and so on.
In any event, there's no need for you to assume anything: the label inside the panel door will show you exactly how the stabs are connected to the busses.

As I said before, that's impossible to answer without knowing what type of circuit that white wire is part of, and which breaker(s) the other wire(s) in that circuit connect to.
--
Regards,
Doug Miller (alphageek at milmac dot com)
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If the white wire is from circuit 13 and there is an energized load on it will probably be between 220 - 240 volts and zero. With no load it should be zero. If the white wire is from circuit 15 the reading can be anywhere from 120 to zero depending on the load or no-load. Usually breakers alternate phases on the same column. So between breaker 13 and 15 you should have 220 -240 volts because they are opposite phases.
What brand of circuit breaker panel is this? What was the problem that you originally experienced that caused you to call an electrician in the first place?
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wrote:

On my panel (Square D), breaker positions down the left side are numbered:
1,3,5,7,9,11,13,15,17,19
and on the right side:
2,4,6,8,10,12,14,16,18,20
1,2,5,6,9,10,13,14,17,18
are on one leg.
3,4,7,8,11,12,15,16,19,20
are on the other. Any 2 adjacent positions are on different legs, allowing the use of a double pole 240V breaker in any 2 vertically-adjacent positions.
--
11 days until the winter solstice celebration

Mark Lloyd
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On Fri, 14 Dec 2007 15:48:56 -0600, Mark Lloyd

Why don't you celebrate the solstice on the solstice?
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why not just call it Merry Christmas? Since that IS the reason for the season.
s

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