Today, I had two rooms in my house lose power for no apparent reason.
Both rooms are connected through the same circuit breaker, but this
didn't trip. I know that there was power in my house earlier in the
morning. After checking all the breakers, and reseting them three or
four times, power hasn't come back into the two rooms. Using my DMM, I
get a reading of 0.3 V at all connections on that circuit. I've checked
the power going through the circuit breaker, and it's reading 120V.
Does anyone have any suggestions as to what could have happened to
cause a lose of power? There doesn't appear to be a short in the
circuit as the breaker hasn't tripped. Could it be that the breaker is
bad, and needs to be replaced? All advice and suggestions are welcome,
If you've got 120V at the output terminal of the breaker (I assume you
measured it relative to the neutral bus in the breaker panel) then you
MUST have an open circuit somewhere, probably at a terminal screw on
some device like a receptical, or a loose wirenut joining two or more
It's what we used to call a "loose disconnection somewhere". <G>
Because you weren't to clear about describing what you measured 0.3
Volts TO, the open circuit could be in either a hot (black) lead or a
neutral (white) lead.
Start looking for an open connection, but don't electrocute yourself in
You did not say, but the usual cause is a GFI. Are all your bathroom,
garage, outdoor and kitchen outlets working? If not start looking for the
GFI's and reset them.
Other than that it means the first outlet that is not working or the
last outlet that is working on that circuit has the problem. The likely
problem is this case is a wire has come loose from one of the back stab
connections at the outlet. You need to take a look to find it.
Note: that small voltage you are reading is meaningless, ignore it
(pretend it is 0) On the other hand don't assume any of the outlets or
other devices are safe to work on, there could be a powered wire in the box
so be careful.
I just worked on a ladies house that had that exact thing happen only
it was a shared backstabbed neutral that came loose. It blew the TV,
DVD player and a Sony clock radio in the bedroom. The clock radio
needed a fuse replaced in the xformer but the TV and DVD might be DOA.
When you check the voltage, check it to ground or use an AC voltage
probe. If the hot is gone trace it back toward the box you'll probably
find a bad connection or popped back stabber in the circuit somewhere.
I've got an amusing back-stab tale for you all..
I never liked back-stab(stick wire in no screw required) for as long as
I've been on the other side of a common recept. I don't know why.
Something about them just screamed "insecure!!".
15 years later: Present day. Last month, I had a hunch that the
outlets in my apartment may not be totally up to snuff. So I check a
few of them out and sure enough - backstabbers.
In total I converted 4 outlets to "side-wind"(wire around copper side
posts) and rehabed an existing side-wind(snipped back the wires and
re-torqued them.) The outlets were all part of the living-bedroom
exept for one - a kitchen branch for small appliances.
Now I'm not kidding you - but both the living- and bedroom TV look
better - sharper, more accurate colors, less "fuzz" or background
interference. The sets both produce an awesome picture even with
Contrast turned down to 40% of max. The surround system connected to
that livingroom set sounds better, too.
I'm sure I'd get the same results with a "back-screw" wiring, but
please - ANYTHING but a back-stab!
I have seen more than one backstabbed plug that looked perfect (not
visibly loose or burned), but was not making contact internally, causing
the plug and others down the line to be dead. Backstabbing should be
illegal. Hell, it shoud be illegal to make a device that can be
We had a similar problem in our home. The power to our unit was
underground and the freeze and thaw had caused the cable to first
partially break and then completely break and we lost all power. The
cable had to be replaced.
First thing, when I checked the voltage at each outlet, switch, and
GFI, at the terminals where the wiring connects, the wiring itself, and
into the outlet openings. I checked with both hot to neutral, and hot
to ground, and got the same reading at all points (0.3, or basically
zero.) I did this with my DMM set to AC voltages.
One of the first things I did was to check the GFI in the bathroom, as
it is at the tail end of the circuit. It wasn't tripped, but I did test
it, and reset it twice. All other outlets and lights work in the house,
and the only GFI is in the bathroom (twenty year old house).
I've checked most of the wiring that I can get to, except that attached
to the GFI in the bathroom. I didn't think that it was possible for the
wiring to pull out of a recepticle, like it has been described here,
but I'm going to start retracing everything tomorrow morning. It's
really dark right now in that part of the house.
Thanks for the help.
Uh, Chris.... I presume that GFI is at the "tail end" of ANOTHER
circuit, not the one that's dead, right?
It does very much sound like you've got an open in the hot lead, as it's
unlikely BOTH the neutral and ground leads would developed open at the
same time, though a ground lead could have opened years ago and not get
Well as this poster says you must have an open somewhere. Since the hot
and neutral both test 0 the open is probably in the hot also as this
Well if there's no power you couldn't test it. You can't reset it
'cause you can't test it.
Look back toward the box. You might have to take the panel off. (don't
do this if you're not comfortable with it) to see where the circuit
leaves the box. Then you need to find where all the boxes where the
connections are. Most codes require theses to be visable and available
but I have seen them buried. Easiest behind drop ceilings, worst behind
BTW non metalic sheath, conduit or BX?
Forgot to ask, do you by any chance have a window a/c in one of the
rooms that went dead? Regardless of what the a/c sales people/ads tell
you, window a/cs should be on their own separate circuit. If not, you
are just begging for problems.
Actually, I did have a window a/c in the room before it lost power. As
for the rest of the story, I've checked all the receptacles, switches,
fixtures, anything that's part of that circuit. Nothing looks out of
the ordinary. Since I've never trusted the backstabbed approach, I've
taken the time to attach all the wires to the screw posts on the
respective piece. But when I've checked the voltage on the bare wires,
I still get nothing with the breaker on. I replaced the GFI in the
bathroom, which is the start of the circuit it looks like, and took the
other one and tried to test it on a good circuit in the house. It won't
reset, and shows no power going into it (when properly wired) so I'm
guessing that's bad. But the new GFI isn't getting power to it to allow
me to reset it.
Can anyone tell me how to test the circuit breaker? I'm thinking that
must be where this problem is lying. When I tested it, I checked to see
if power was going from the hot bar, to the nuetral bar, with my DMM. I
got 124V. Then I checked the screw where the wire attaches too, to the
nuetral bar, and got 124V. I didn't turn off the breaker because I
assumed power was flowing through it, becuase of the voltage reading.
Thanks for all the help, I'm going to still troubleshoot this until I
save enough money to call an electrician.
Well, I finally found the cause to why I lost power in my house. My
smoke detector, which is hard wired into the house, was shorting out
and melted part of the wiring. Currently have that part of the circuit
isolated with no power to prevent it from causing a fire. Now to call
the electrician to fix that. Thanks for all the help.
I would have such important loads put on a dedicated breaker, if for no
other reason than a short could:(
Shutting off power to some detectors:(
NO ALARM WHEN YOU NEED IT THE MOST!
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