circuit suddenly dead - why?

My house has a multi-branch circuit on it. This circuit supplies power to a few bedrooms and a bathroom. The two breakers that supply power to the circuit are 20amp each.
At 7pm tonight I turned on a few things in one bedroom. This bedroom has two duplex outlets. Everything I turned on worked. At 7:15pm the entire room had no power. Neither the outlet I was using at 7pm had power nor did the room's other outlet.
I checked the two breakers that supply the circuit; neither had tripped. There are no gfi outlets involved. In the panel I checked the hot and neutral wires for the circuit; all are tightly attached. All of the other bedrooms in the house had power at 7:15pm with no obvious issues.
What on earth could cause this? How would I troubleshoot this problem?
Thanks,
mh
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Sounds like you have an open neutral. Use a test light and see if you get 120 volts between the "hot" slot of the outlet and the ground. Most likely the neutral wire has come loose in an adjacent outlet. Try plugging a lamp into a "dead" outlet,(make sure its in the on position) and bang on each adjacent outlet to see if the vibration at any outlets causes the light to come on or flicker. If it does, open that outlet and check the connections, especially back stabbed connections

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I checked this: nothing between hot and ground on either of the dead outlets in the bedroom.
mh
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I just found another outlet, in a bedroom next to the one that originally caused a problem, that is dead.
In all of the dead outlets I have no voltage between hot and neutral and no voltage between hot and ground.
I just putlled out the first dead outlet that I found, and it looks fine. All of the connections are tight. When I touched my tester on the hot and neutral screws and on the hot and ground screws, there was no voltage.
This seems bizarre to me. Everything worked fine a few hours ago and has been working fine since I bought the house three years ago.
mh
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OK, it's not an open neutral, it's the hot leg that's open. It doesn't sound like an entire circuit, so again you're looking for a bad connection, but on the hot leg. I would check all live outlets that are near the dead outlets. You want to find an outlet with power coming in, but the hot leg of the downstream wiring is loose

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I just checked the two breakers that supply the multi-branch circuit, and there is voltage between both hot screws and a neutral. No obvious problems at the panel.
I will start on the live outlets close to the dead ones and see what I find.
Thanks very much for your help.
mh
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snipped-for-privacy@yahoo.com wrote:

Turn off the breaker that you know supplies the "multi-branch circuit" and then look for outlets/lights that worked before but are now NOT working. Then open each of those checking for bad connections of any kind. This may identify the point of a bad connection. You may find an outlet with wires pushed in holes, or wire nuts which have become flaky.
I would also be suspicious of the new box and work done at that time, since it was only three months ago. Perhaps did the worker create some sort of extension on the wire feeding your bad circuit? Maybe his/her work has a problem. --Phil
--
Phil Munro Dept of Electrical & Computer Engin
mailto: snipped-for-privacy@cc.ysu.edu Youngstown State University
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Could be a number of things. As RBM suggested a bad neutral connection is one possibility. I would open up the electrical panel to see if there was juice coming off of each circuit breaker. If not then you might have lost one phase and need to determine if it is before the electric meter or after. I would pull the electric meter to find out.
Other things I would check:
Connections on the main breaker. All neutral, ground and hot connections in the main panel. Open up a few outlets at the beginning of each circuit and check for a hot and a neutral. I would run a wire to a water pipe and check the hot to the water pipe. If you have juice, then the neutral is missing. Open up a few junction boxes and check for loose connections.
How old is your house?
John Grabowski http://www.mrelectrician.tv
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How do I do this? Touch the tester to the hot screw on a breaker and to the wire that grounds the panel to the buried rods outside the house?

What do you mean, check for a hot and neutral? Do you mean, place tester probes on hot and neutral screws?
Regarding a water pipe: if I understand you correctly, the idea is that my pipes are grounded (they are connected to the main ground wide in the house which goes to two buried rods). If I have voltage in a box between hot and water pipe, then I know that the neutral is missing in the box. Is this right?
So far all the outlets I have checked are either fine or have no voltage between hot and neutral and between hot and ground.
Age of house: about 40 years. 200amp upgrade was done about three months ago. The multi- branch circuit now causing problems is only one of two original circuits left in the house (the other is a dedicated boiler circuit). There a no other known electrical problems in the house (all other circuits work, no flickering, no popping breakers, etc.)
mh
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You said that you already checked for juice between the breaker and the neutral at the panel. That is sufficient to tell you that you have juice coming from the breaker.

hot
the
Yes
You will have to start opening up outlets and junction boxes in search of a loose or broken connection. Start with the outlets close to the electrical panel. The problem could be in an outlet that is still working. Try shutting off the circuit breaker to see what else is on that circuit and go from there.

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Look for the word "ELECTRICIAN" in your yellow pages.
On 13 Oct 2005 18:50:28 -0700, snipped-for-privacy@yahoo.com wrote:

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Look for "ELECTRICIANS" in the yellow pages.
On 13 Oct 2005 18:50:28 -0700, snipped-for-privacy@yahoo.com wrote:

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What you have is some sort of electrical failure. It's not a big deal, and it may or may not fix itself. Just dont use those rooms at night for awhile or use a flashlight. I'm curious how you knew it was 7:15. Didn't the clock go out along with the power?
On 13 Oct 2005 17:13:58 -0700, snipped-for-privacy@yahoo.com wrote:

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snipped-for-privacy@yahoo.com wrote:

Somehow I suspect there is a GFI involved. Do you have any anywhere in the house? This circuit you are talking about includes a bath and should have one added if it does not yet. Often GFIs show up in odd spots.

--
Joseph Meehan

Dia duit
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You're not in Vancouver, are you? It sounds just like an old house where I rented a suite until it was sold (ominous music...) 3 years ago.
Like you, one circuit, occasional flicker, sometimes nothing for months. Then *blink*, dead circuit, could be 5 minutes or 5 hours, no telling, then *blink* back on again.
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On Fri, 14 Oct 2005 11:29:35 GMT, "MasterBlaster"

Check your GFIs. Many circuits can be subject to nuisance tripping. As a previous poster said, GFI's can be in oddball locations, away from the main circuits they control. There are two in my house... One in the garage and one in the kitchen. These are the outlets that have a "Reset" and a "Test button".
Beachcomber
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Very often, what's done is to wire the power to socket 1, then 2, th en 3, and down the line. If the wire that comes off the back of socket 1 (going from 1 to 2) is bad, then you lose power in sockets 2, 3, 4, etc.
The solution is to turn off the breaker. And then go around and find which socket went dead that was live before. Pull it out, and make sure the wires are under the screws on the side, not the "stab in" things on the back.
--

Christopher A. Young
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