Wiring problem

[A Nony Mous]

After 25 years of trouble-free use with _no_ changes at all, I am suddenly having problems with a 115 volt grounded branch circuit. The circuit is connected to a 30 amp breaker and feeds three duplex grounded outlets and a fan/vent hood over the stove in my kitchen. The branch feeds from the breaker into one of the three outlets ("outlet #1") and splits from there to feed the other outlets and the vent hood. I have a microwave (Amana Radar-Range, 20 yrs old) in one outlet ("outlet #2") and nothing plugged into the other outlets. Recently, if I hit the Start button on the microwave, it dies, along with the vent hood. The really weird thing is that if I plug an ordinary work light with a 40-watt bulb into "outlet #3", the work light works, _and_ the microwave and vent hood start working again, at least for a while. When the problem occurs, a voltmeter shows 115 volts in outlet #3, but minimal voltage (maybe 50 volts) in outlet #2. (I cannot remember right now what the voltage in outlet #1 is, but I think it sometimes shows normal and sometimes not.)

Here's what I've done to troubleshoot the problem:

1. Verified that the microwave works okay when plugged into a different branch circuit (in fact, I can sometimes also get the problem to occur with the microwave unplugged, just by plugging the work light into outlet #2, so the problem is not related to the microwave.)
2. Cycled the circuit breaker, pulled power and verified the breaker terminal is securely screwed down, and, finally, switched the breaker with another identical one in the panel.
3. Disconnected all wires from all outlets and ran continuity tests on all parts of the circuit with an ohmmeter. Continuity was good on all wires. None of the above solved the problem, so I did the following:
4. Removed and examined all outlets, looking/smelling for signs of burning or scorching. None found.
5. Bought a new outlet and swapped it for outlet #2 (the one the microwave was plugged into). Problem did not go away, so I
6. Swapped the old outlet removed from outlet #2 for the outlet in outlet #1 (the one that "feeds" the other outlets). Problem did not go away. Did not do anything to outlet #3, since it always tests good.

As I said, this circuit has run without problems for 25 years. Also, there have been _no_ wiring changes of any kind in the house for at least 10 years. No fires, water damage, lightning strikes, etc.

The only thing I can think of to do now is to replace _all_ the outlets with new ones. Does anyone else have any other suggestions?

Thanks in advance for any help.

[Toller]

I hope the 30a breaker is a typo. If not, that is your first mistake.

How is the circuit wired? Are the outlets wired sequentially? Are they pigtailed?

Obviously you have a bad connection somewhere between outlet 2 and outlet 3. Since replacing outlet 2 didn't help, the problem is probably at outlet 3. Try replacing that.

Hard to give any other advice without know how the circuit is wired.

[Joseph Meehan]

If that is a 30 amp breaker, then I would look for all kinds of problems. It should be 15 or 30 depending on the wiring and devices it protects. If someone wired it that way, I would expect to find all kinds of strangeness and dangerous other errors in the wring.

As far as I can tell from what you have done, is you may well have a floating neutral of one kind or another. That could be nothing more than a loose wire at the breaker box.

You don't have aluminum wire do you?

[Jake]

I'd bet on a floating neutral, too. And, us electricians really hate aluminum.

Jake

[HA HA Budys Here]

WE electricians...

[Curmudgeon]

Last year he couldn't spell electrician...now he are one.

[spamfree]

You mean it should be a 15 or """20""".

[A Nony Mous]

Thanks to everyone for the help. It's a 20 amp breaker, not a 30, the wiring is all copper, and I had already checked everywhere for a loose connection. So, following Toller's suggestion, I replaced outlet #3, and all is well so far. After closer inspection and testing, it appears that the other outlets were actually wired in series downstream from outlet #3. Even though #3 voltage tested normal, it apparently had some internal problem that prevented the current from getting to the other outlets. Your advice has saved me the cost of a service call from an electrician. I really appreciate the help.

[Joseph Meehan]

Yea, I can't type, even when I am trying to comment on an error. ;-)

[HA HA Budys Here]

Your problem probably stemmed from the fact that outlet #3 was back-stab wired, right?

Although newer residential grade receptacles cannot be backstabbed with anything larger than #14 awg, older ones allowed it. NEVER backstab your outlets, always make a proper splice and pigtail the outlets individually!

[A Nony Mous]

Probably so, and to avoid that problem when I replaced it and when I swapped the other outlets, I used the screw terminals on all of them. Thanks for the advice. Now I'll know where to look if any other outlets start giving me problems.

[indago]

040527 1555 - A Nony Mous posted:

The wires in the boxes should be brought together with a wire nut and leave a pigtail to connect the outlet to. Then you wouldn't have the downstream electrical failures.