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Question DetailsAsked on 2/2/2013

What could be causing intermittent low voltage on all AC outlets along the same circuit?

The 3 bathrooms in our home each have outlets that are on the same circuit in the electrical breaker box in our basement. The breaker in the box is a GFCI with a white square button in addition to the on-off breaker switch. All wiring is copper.

The issue we're having is an intermittent voltage drop on the outlets in the bathrooms. If we turn the breaker off & on again, we can use a voltmeter to find 118 volts in all of the bathroom outlets. If we then plug any device into 1 of the outlets (say, an electric razor), the voltage in that outlet & all outlets in each of the bathrooms drops to just 90 volts. If we then plug another device into any of the outlets, the voltage at all outlets drops to 10 volts. Even if both devices are then unplugged, the voltage at all outlets remains at just 10 volts. Turning the breaker off & on again returns the voltage to 118 volts at all outlets.

We've replaced all receptacles and ensured all connections are tight. Any other ideas?

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5 Answers

1
Vote

Loose connection along the circuit, or a defective breaker, is the most likely cause.

Source: http://www.bayareacool.com

Answered 5 years ago by BayAreaAC

0
Votes

Loose, burned or corroded connection. Just like the first responder said

Source: http://kestrelelectric.com

Answered 5 years ago by Kestrel Electric

0
Votes

In case your problem is not solved, the following thoughts. IF solved, would you let us know what caused it?

This sort of failure occurs in GFCI breakers at times. What may be happening is the breaker should have tripped off due to a ground fault, but there is a minor short in the GFCI circuitry that is letting a bit of juice leak into the circuit. When you reset the breaker this short goes away because the full breaker is in full contact again, but when you put any significant load on it the GFCI trips, once again allowing that stray voltage through.

It is also possible tht you have a neutral fault, so when you start using the circuits the neutral heats up and loses contact with a connection, but 10V of stray voltage is across to the circuit (possibly on the surface of an outlet or through bad insulation, for instance), or bleedover from another circuit using the same neutral. You can also sometimes get this kind of funny result (though on all outlets on one half the breaker box) if there is a ground for neutral swap or bad neutral connection in the breaker box.

I would guess a bad GFCI breaker, but to check you can buy LED indicator plug-in circuit testers. Operate some device on one outlet, then with the tester on a second outlet plug in a secdond device. Even if the tester reads OK initially, it should show a fault when the second device is plugged in and voltage drops to 10V.

Answered 5 years ago by LCD

0
Votes

the circuit is not well grounded check the panel broad grind terminal make sure it is attach to neg ground make sure gfci is polarity match and well grounded its something in grousing circuit

Answered 1 year ago by troubleshooter1

0
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In rereading this for possible use as a reference for another question, I see I did not explain a couple of things clearly, and totally missed one - though the other answers indirectly addressed part of it:


1) the 110/120V versus 90V difference could well be, as other contributors said, a bad grounding issue - basically the difference between the voltage between lie and neutral (which is cut off when the GFCI trips) and live versus ground - you appear to have a 10-20V differential beetween the two, which wouldnormally be due to either a bad ground, or a ground rod (or grounded pipe) close to an electrical device putting juice into the ground like an air compressor or wellpump commonly. Basically, the neutral (which goes back to the utilityi ground) and your system ground (bare gorund) are seeing different grounds. 10-20V difference is not uncommon - during strong norhtern lights in northern states, or during electrical storms, cn reach hundreds of volts at times even without a direct lightning strike. I have seen voltage drop to about zero or go up to 400-600 or more on 120V circuits during strong northern lights, where they are affecting long transmission lines.


2) the 10V could actually be zero on that circuit, with bleed-over from interconnected wiring, from some low voltage device - some electronic devices and some chargers and plug strips and UPS devices sometimes bleed some different voltage in neutral than ground during use, as can MOV surge protectors. Commonly from 2.5-12V. Generally shows up in buildings where the neutral and ground are not interconnected at the panel, but very low amperage voltage diffferences like that can persist in a circuit even if its breaker is off.


3) the 10V could also be poor calibration of the meter or weak battery in the meter - check with the electrodes a couple of feet apart across a piece of non-electrified metal like a metal tabletop or metal trim or such - if it does not read zero that could be the issue.


4) I would check polarity, as other comment said - might be you have a polarity issue which is confusing the GFCI breaker. Or, it is as simple as one device is loading the circuit so heavily (maybe due to bad wiring that is not connected till something is plugged in) that adding a second one is just tripping the breaker because of excess current draw. This migiht mean disconnecting the wires at the panel, then doing a full continuity trace along the length of the circuit, tracing all wires and ensuring there is no cross-connection (without any loads on the circuit) between live, neutral, and grounds (though depending on your house wiring scheme, neutral and ground may be joined at individual boxes, rather than just at the panel). Also - remember seeing some GFCI/AFCI's which checked not only that the power passing through live wire matched that in the neutral, but also checked that the ground was not carrying juice - so if that is the case an interconnected neutral and ground can confuse it.


5) Defective GFCI - I have seen them (especially electronic ones) do some pretty unusual things - and some pretty impressive fireworks when they short out internally.

Answered 6 months ago by LCD




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