Ponder this about GFI failure

[mikeames]

In my own garage I have a 20 amp MWBC with 2 GFI receps on it. Thats all this is on this circuit. This circuit is fed from a 100 amp sub I also installed myself.

In the same garage I have a fridge fed by a single 20 amp recep which is also feed from the same panel the GFIS are feed from.

Two days ago I put the fridge on a cheap $6 belkin plug in surge supressor, and today I wen to plug in a vacume to the GFI and they were both dead. They would not reset. (yes power was present). The GFIS have been fine and now all of a sudden the only change is the surge supresson and now their dead? Is there a connection? Why?


The reason I installed the cheap surge supresson is a learnign experience. I have a plasma TV in my living room that uses a HDMI balun or HDMI over a pair of Cat6 cables. When the fridge cuts out it causes the picture to blip or drop out for a secone. The reason is the balun needs a steady ground reference. When this is disrupted it will cause this error. This is documented. My thinking is the fridge is causing disturbance. I figured I would plug the fridge into a cheap surge protector to see if it made a difference. In the end it did not and at the same time blew out the GFIs??
The TV and baluns are already pluged into a surge supressor.


Any ideas or comments as to why the GFI were affected?

 

[Glenn Anderson]

El-Cheapo surge strips have three inexpensive disk type capacitors installed; hot to ground, hot to neutral, and neutral to ground. If a surge hits and one cap is weaker than the others the GFCI may see an unbalance and trip.
Had this happen a few times at work.
We had 50% GFCI failure rate depending on surge characteristics.
Glenn

 

[mikeames]

These did not simply trip they are fried. They will not reset. I have to install new, and when I do I am removing that paper weight piece of crap that caused more damage that its worth.

 

[Open Neutral]

El-Cheapo surge strips have three inexpensive disk type capacitors installed; hot to ground, hot to neutral, and neutral to ground.

Glenn

Those are NOT caps. They are MOV's. A metal oxide varister is an anti-Ohm's Law device. It draws no current until the voltage reaches a knee point, when its impedance drops sharply.

A short spike gets eaten, but a longer one should trip the outlet strip's breaker. A long enough, big enough, surge will cause the MOV to explode. [If you shake an outlet strip and it rattles; guess what happened.]

In any case, each spike kills the MOV a bit at time. Enough small ones and while it looks intact, the MOV is a placebo.

 

[Open Neutral]

These did not simply trip they are fried. They will not reset. I have to install new, and when I do I am removing that paper weight piece of crap that caused more damage that its worth.

I can't envision a situation where an outlet strip destroys a GFI. I can see a surge that kills both the GFI and the MOV's.

On your original problem, a balun is a BALanced to UNbalanced transformer. It should have input-out isolation. Measure it with an ohmmeter. [A RF balun may not have DC isolation, hence my hedging.] I suspect the voltage drop upsets the boob tune itself. Do you get dropout when watching OTA programming as well?

 

[mxslick]

I can't envision a situation where an outlet strip destroys a GFI. I can see a surge that kills both the GFI and the MOV's.

Me too, and I think that is what happened. In fact since they are fed with a MWBC I would also look closely for a bad neutral connection somewhere on the line. Take two voltmeters, measure at the GFCI's and record the voltage as the fridge starts and runs.

On your original problem, a balun is a BALanced to UNbalanced transformer. It should have input-out isolation. Measure it with an ohmmeter. [A RF balun may not have DC isolation, hence my hedging.] I suspect the voltage drop upsets the boob tune itself. Do you get dropout when watching OTA programming as well?

DO NOT try to measure a balun with an ohmmeter!! You can easily magnetize the core material and ruin the balun.

I do agree that the voltage drop on fridge start is the real problem causing the drop out on the tv.

 

[mikeames]

I learned something. I learned what balun is and I learned I dont really have one.

I have this http://www.hdtvsupply.com/hdmi-over-cat6.html
The neutral is solid at the service at the subpanel and at the GFI themselves. I am certain its not that.

The dropout occurs when the fridge both starts up and when it kicks off. Sometimes the TV drops out when the HVAC fan kicks on but not all the time. I can identify the problem I just dont understand it enough to remedy it. I am begining to think this HDMI over cat 6 is just too delicate for my application. I read the directions and I know it is very sensitive to ground reference.

 

[gar]

101102-1532 EDT

mikeames:

For the moment ignore the TV problem.

First, remove one of the apparently bad GFCI receptacles and connect a cord and plug to its input terminals. Don't connect a ground wire even though it should make no difference, or any load.

Apply power with no output load. Can you reset the GFCI? If not, then remove the cord and open the GFCI, look at the mechanism and circuit and see if there is any obvious problem. You should be able to operate the mechanical system and get it to latch.

If you can mechanically latch the device, then reconnect the cord and power to the GFCI. If it doesn't immediately trip, then connect a 25 W incandescent from a hot output point to the neutral input terminal. It should trip. If it won't, then there are damaged electronic components.

Report back.

.

 

[Jraef]

My thoughts on the overall situation.

You have had a bad neutral connection somewhere in there all along, maybe all the way back at the main panel. That has been causing your "blips" in the TV when the fridge starts and stops, the HVAC fan too. The current surge was causing the neutral connection to fail momentarily. The cheap surge suppressor probably popped the MOVs and because that itself sometimes causes a flash-over, the collateral damage inside that plug strip was the final straw for your bad neutral connection, which is what your GFIs are now picking up on.

 

[Glenn Anderson]

El-Cheapo surge strips have three inexpensive disk type capacitors installed; hot to ground, hot to neutral, and neutral to ground. If a surge hits and one cap is weaker than the others the GFCI may see an unbalance and trip.
Had this happen a few times at work.
We had 50% GFCI failure rate depending on surge characteristics.
Glenn

My bad, MOV - Metal Oxide Varistor, not Capacitors.:roll:
Glenn