I notice that the sevice panel in my house has two 15 amp circuit
breakers which either both must be on to supply power or both off to
shut-off power. I might not be using the term circuit properly, but
what this powers are mostly hallway lights and the garage lights
including a garage door opener. All the other switches (circuit
breakers) in the service panel operate independently except these two.
When might it b OK to have a need for two 15 amp circuit breakers
working together like this? Next time I have a pro out, should I have
this service panel reviewed? Is this configuration doing the work of a
single 30 amp circuit breaker? Thanks!
On 30 Jun 2004 23:40:49 -0700, East Coast put forth the notion that...
Absolutely... the sooner the better.
No. You most likely have two circuits sharing a common neutral from the
panel and the neutral is open somewhere, or you've got two circuits
crossed somewhere, causing a backfeeding condition. Either way, it's a
hazardous situation and needs to be checked. This is a job best left
for a professional electrician.
No, they are not mechanically connected, since the two switches can be
switched in the on or off position independently. However, unless they
are both switched on, power isn't supplied. Likewise, unless they are
both switched off, power isn't turned off.
I discovered this while I was replacing a light switch in the hallway
and needed to shut off power. I went through the service panel
clicking one switch at a time and never could shut off the power for
this area of the house. So I turned every switch to the off position
and that finally shut off power. I then found out that these two side
by side switches for the circuit breakers in the service panel were
operating as if they were one big switch, then I could shut off or
restore power to this area. They are both 15 amp breakers.
That's what he said.
Makes perfect sense. Probaby two individual circuits leave panel.
Share common box some place. DIYer following instructions from
some internet newsgroup connected all hots and all neutrals
together. Luckily, they were on the same phase. There ya go!
But he said the power doesn't come on unless both breakers are on.
If some DYIer tied the hots of two circuits together, power would be
supplied if _either_ breaker was on.
I do suspect that is the case (two circuits' hots tied together) and the
text in the post doesn't match what really happens, just that as written
it doesn't make sense.
Do you have a volt meter? If so what is the voltage at the door opener
outlet when one of the breakers is turned off. I would assume it is
not a full 110 VAC.
Also what is the voltage when they are both turned on?
It's possible that someone was using these two separate breakers at
one time for a 220 VAC source (maybe still is) & then put a 220 to 110
step down transformer on the line somewhere to power the lights &
opener. Another possibility is that there is weak voltage due to bad
breakers or bad wiring & so the wires are jumped together somewhere to
bring up the total voltage (not very smart or safe) by adding the two
It's amazing what some people will do & I have even seen some
so-called electricians do some pretty weird things.
| No, they are not mechanically connected, since the two switches can be
| switched in the on or off position independently. However, unless they
| are both switched on, power isn't supplied. Likewise, unless they are
| both switched off, power isn't turned off.
Your statement is self-contradictory. You are saying in one part that
one is on and one is off, that power isn't supplied, and in another part
are saying that power isn't turned off. It's either on or off, or maybe
some weird voltage.
So let's go over this in detail. And this is what I would examine if
I were there diagnosing this for you:
Label these breakers for this purpose as A and B. The box should have
them numbered, so for consistency, make A be the lower number and B be
the higher number. Do this test with all other breakers ON that would
normally be on.
1. If A is off and B is off, is the power to that area on or off?
2. If A is off and B is on, is the power to that area on or off?
3. If A is on and B is off, is the power to that area on or off?
4. If A is on and B is on, is the power to that area on or off?
Now repeat the test, but this time with all other breakers OFF, except
the main would be ON.
5. If A is off and B is off, is the power to that area on or off?
6. If A is off and B is on, is the power to that area on or off?
7. If A is on and B is off, is the power to that area on or off?
8. If A is on and B is on, is the power to that area on or off?
9. What actual position numbers are breakers A and B in? How many
breakers and breaker spaces (give both numbers whether different
or the same) are between them (0 for immediately adjacent)?
Turn all breakers off, including the main breaker, and any breaker or
switch you might have feeding this panel. Remove the front and find
the wires leading to the two suspect breakers. Examine them very
10. Does each breaker have exactly one wire, or more than one wire?
11. What color wire(s) go to breaker A?
12. What color wire(s) go to breaker B?
Follow the wires back and see if you can find if the wires join a
common cabling, like a single Romex. If so, look at the white wire
that cabling has, as well as the bare or green wire, and trace them
to where they are attached. Are they in fact attached properly and
If the wires for these breakers go to separate cabling, please report
this fact the best you can. In this case, leave these breakers off,
put the panel back together, and restore power except for these two.
Then example every receptacle and light and take an inventory of exactly
everything that is without power. If you have plenty of time, you
might want to open those boxes and see if you can figure out where the
separate cabling joins back together, You may have what is known as a
"ring circuit", which is usually not compliant with NEC code in the US
(and with 2 separate breakers, definitely is not compliant). Or you
maybe have some (probably miswired) shared neutral "home run" circuit.
Absolute clarity and complete detail is required for us to figure out
what you might actually have. The number of possible ways to miswire
circuits is astronomical. Guessing is usually futile. Assumptions can
get people hurt or killed.
Tell us where (city, state) you live. Maybe someone here happens to
live close to you.
| It's amazing what some people will do & I have even seen some
| so-called electricians do some pretty weird things.
When more and more things are made foolproof,
the fools will find a way to keep up.
On 2 Jul 2004 15:46:21 -0700, Doordoc put forth the notion that...
Why would someone add a transformer to get 110 from 220 if they already
had a neutral?
"Weak voltage" due to bad breakers?
I'm amazed already. Especially since I told him two days ago it was
either two circuits crossed together and/or an open neutral. I think
it's time he called an electrician.
Because their human & what may seem to be a brilliant idea to them may
not be so great to others. I have actually seen jobs (usually gate
operators in my experience) where they have done this. Use 220 to
power the operator & a stepped down transformer to power accessories.
I can also imagine that at some time someone has done this to get a
220 volt outlet in a garage & they didn't want to spend money to
upgrade their service panel or do alot of wiring. Therefore you would
have to turn off both breakers to kill all of the power to the other
And yes he probably should call an electrician real soon!!!
Maybe not bad breakers...but I have had low voltages due to poor
connectivity at the breaker lugs. I had a stove with AL wire that had arced
in the lug making for only about 75 volts at the plug. Everything looked OK
in the panel. It took some head scratching to figure that one out... :)