GFCI Receptacle Question

[poboy]

I installed a Victron 600S battery monitor this weekend and while completing the setup, I noticed that one of the GFCI 120V receptacles was producing a slight buzzing noise, but only when being run on the Xantrex Pro 1800 inverter. When on shore power, there is no buzzing. Figured the receptacle was bad, so I bought and installed a new one. Still buzzing, again, only when on inverter power. Receptacle does not appear to be getting warm and still works when you plug something in. I have never noticed this before the battery monitor installation, though I can't imagine how that could have caused this.

Any thoughts or suggestions are more than welcome!

[S/V_Surya]

First thing that comes to mind is xantrex does not produce true sine wave as opposed to shore power. Make sure it is grounded also. You need to do some testing disconnect things to isolate problem. But I suspect it is an irritant and not serious issue.

[poboy]

Thanks for the reply. I agree with testing. Plan to take the battery monitor out of the line first since that is the only new thing in the system. Also, Xantrex states that only certain GFCI receptacles are acceptable for use with the Pro 1800. Need to make sure I've got the right one installed. The fact that it just started doing this after installing the inverter a year and a half ago is what puzzles me.

[rtbates]

Be careful what you power with that inverter, IF as it appears to not be a true sign way. Lots of electronics won't last long..

[poboy]

It is in fact a modified sine wave unit. Have had no pro lens with computers, LCD tv, DVD player, microwave, dorm fridge, etc. I am hesitant to use for recharging certain items like cordless tools, though it charges my iPhone just fine.

[btrayfors]

FYI, the "modified sine wave" term is misleading, even if it is used everywhere.

The output from such an inverter is really a modified square wave....nothing like a sine wave.



(illustration from rimstar.org)

Some electrical appliances have no trouble with such a wave, some do.

These days, true sine wave inverters are available for not much more than the "modified sine wave" inverters of yesteryear.

Suggest you replace it when you get a chance.

Bill

[David M]

Many things buzz from not having a true sine wave running through them. With my old non-true sinewave inverter, on rare occasion I had "wall warts" get destroyed by them. It is difficult to determine if your GFCI outlet will become a victim.

[poboy]

I just feel like there's something else involved here. I mean, for a year and half, the old outlet did not have this problem. Neither did any of the other outlets. Install a battery monitor and presto - buzzing outlet. And only one out of five. Replace the offending unit with a brand new and the problem persists.

First step is to get back down to the boat and take the monitor out of the circuit and see what happens. That is the only variable I can find in the equation. Am I missing something?

[Coolruns]

Would have to be there to see the entire circuit to be sure.

Could be a frequency issue from the Inverter. Higher than normal or lower than normal frequency can cause buzzing electrical gear.

Because it is only affecting the GFCI, it is possible the battery monitor is leaking current to ground and the GFCI may be on the "cusp" of a trip - odd that it is localized to one GFCI.

I would break the circuit on the battery monitor and see if it goes away.

I am interested to hear what you discover.

Best Regards,
DJ

[teejayevans]

BTW, some newer GFIs are not mechanical, so you have to reset after turning off the power, a PITA.
Tom

[CharlieJ]

The battery monitor could not possibly be causing this problem.

Think about it...if properly installed, the shunt is in the B- line between the battery bank's B- and the B- of all DC loads and sources. The data from the shunt is sent to the BMV readout via a telephone patch cord. All of this is in the DC system.

On the AC side, the GFCI operates by monitoring the current into the device on L and back out of the device on N and trips on an imbalance of 5 to 6 mA. There is no connection between the two (AC and DC) systems.

My opinion is that it is a MSW issue OR you have developed a circuit problem in the circuit that the GFCI is protecting, but this is pretty unlikely. A SureTest 164 would tell the tale if you can find a marine electrician who has one.

As to why the buzzing now and not before? Probably can be attributed to the aging of the inverter or the sensitivity of your hearing :-)

Charlie

[capn_billl]

The buzzing would make me nervous. Did you try swapping it with one of the working ones?

[poboy]

Charlie -

I agree completely with your thoughts regarding the BMV. The only reasons I am going to take it out of the circuit are a) it is the only known change in the system and b) the positive lead for it is attached to the same positive terminal as the inverter. I sincerely doubt any difference will be noted, however.

Capnbill - the buzzing makes me very nervous as well. I did not swap with a working unit, but actually replaced the original outlet with a brand new one. Problem persisted. I am leaning towards agreement with comments regarding MSW and the inverter having a little age on it. But, the fact that the other GFCI outlets are
not affected still gives me pause.

I should be back on board this weekend and will know more after further testing. Thanks so much for all of the replies!

Paul

[capn_billl]

Originally Posted by poboy

Charlie -

I agree completely with your thoughts regarding the BMV. The only reasons I am going to take it out of the circuit are a) it is the only known change in the system and b) the positive lead for it is attached to the same positive terminal as the inverter. I sincerely doubt any difference will be noted, however.

Capnbill - the buzzing makes me very nervous as well. I did not swap with a working unit, but actually replaced the original outlet with a brand new one. Problem persisted. I am leaning towards agreement with comments regarding MSW and the inverter having a little age on it. But, the fact that the other GFCI outlets are
not affected still gives me pause.

I should be back on board this weekend and will know more after further testing. Thanks so much for all of the replies!

Paul

The reason I asked is twofold, one put the "bad" gfci in a ciruit the current gfci is not buzzing, the second to put the "good" gfci in the problem circuit. This definately isolates and eliminates the suspect component. ( it also eliminates the possibility that a particular brand, or manufacturing defect in the new one makes it more suseptable to this problem).

Then when you have eliminated the impossible, you are left with,... a bad ground.
GFCI outlets rely on a good ground connection for proper operation. A corroded high resistance ground somewhere between the inverter, and the buzzing GFCI is the most likely culprit. You may have tipped the bucket on the bad ground by adding an additional load on it with the battery monitor.

GFCI outlets use AC, but a DC bias on the AC signal can fool it into thinking it has more ground leakage than it does, (they are all semiconductor now).

Start at the buzzing GFCI, and trace the ground wire back to main power, especially between the inverter and the outlet, as you stated it does not buzz when on shorepower.

This is probably a battle of inches the trip point of a GFCI is 5ma. a small amount of corrosion at each connection point adds up to a problem.

[goboatingnow]

On the AC side, the GFCI operates by monitoring the current into the device on L and back out of the device on N and trips on an imbalance of 5 to 6 mA. There is no connection between the two (AC and DC) systems

for american boats built to ABYC there is, the protective earth is connected to the Battery negative.

Dave