Ground fault tripping

[Wayne K]

I have not experienced this before. I am tripping a gfi on a cmd24d controller. Will a wet connection on the output of the controller trip a gfi or is it most likey on the ac side before the circuit board? Cord to unit is in good condition. Just looking for somewhere to start looking at.

Wayne

[tlogan]

MY guess would be the AC side, so I would start there. I've had the GFCI outlets go bad, squirrels gnaw on the wire (AND on the light string),plugs get wet, etc. It could be a lot of things on the AC side. A simple outlet and/or continuity tester are big help here. 

[TheDucks]

4 hours ago, Wayne K said:

I have not experienced this before. I am tripping a gfi on a cmd24d controller. Will a wet connection on the output of the controller trip a gfi or is it most likey on the ac side before the circuit board? Cord to unit is in good condition. Just looking for somewhere to start looking at.

 

Wayne

It is probably the PSU (internal) line filter causing excessive leakage (If the AC Plug-extension connection is dry). Those filters dump the RF switching noise into the Ground lead (normal). When the noise level increases, is where it gets excessive.

Simple(ish) test. Plug the cord into a different GFCI (Bathroom or Kitchen...)

FWIW if it ever got bad enough for the DC side to cause a Trip, you have probably damaged a lot of interconnected LOR stuff

 

[Mr. P]

If it were the dc side I would expect it to blow a mosfet and not the GFCI.

[dgrant]

Supposedly, a GFCI looks for continuity between the hot(Black) wire and the ground(Green) wire. If it finds any connection, its supposed to trip. So if water, completes a connection between those two wires, it will trip the gfci therefore assuming you were referring to the power input to the controller in question and tripping the outlet gfci that the controller is plugged into. So you need to insure that power lines to the controller, are not submerged in water on the ground. Elevate them or protect them. Next, we see GFCI trips when an output cord going to a prop, gets submerged and quite often, when on a metal stand, stake or similar, into the ground. Example, it's happened to me for some simple tomato cage led trees that water made the connection on the power cord, at the tree itself, to the metal of the tomato cage. The result was a tripped gfci. GFCI's are very sensitive as they should be but this does not stop them from failing either....they do fail.

Edited November 25 by dgrant

[k6ccc]

36 minutes ago, dgrant said:

Supposedly, a GFCI looks for continuity between the hot(Black) wire and the ground(Green) wire.

Common belief, but incorrect.  A GFCI outlet or breaker does not care at all about the ground connection.  In fact a GFCI breaker does not have any connection to ground, and either will work fine on a 2 wire circuit (no ground).  What a GFCI outlet or breaker is looking for is that the amount of current on the hot and neutral wires are the same.  If they are different by more than about 5 milli Amps, the GFCI will trip.  The logic is that if the hot and neutral are not the same, then current is leaking somewhere.  It does not care where, only that it is leaking somewhere that it's not supposed to.  In most cases, that leak is to ground, but not always.  For example it is somewhat common practice (and perfectly legal in most situations) to have two 120 volt circuits that are on opposite phases to use a common neutral.  Can't do that if either circuit breaker is a GFCI because now you are getting neutral current from both circuit together on one wire.  Will trip the GFCI every time.

These days there are also Arc Fault Current Interrupters (AFCI), but that's a whole different discussion.

 

[Wayne K]

Thanks everyone, I seen the first couple of post earlier in the day and just got back in here and read the other ones. Took advantage of the warm weather to get finished up before the cold gets here.

Well thru the process of elimination.

# 1 changed controller out, same problem.

# 2 Pulled each channel connector apart and tried each channel, Same problem

# 3 went to shop and got longer extension cord so I could get to another gfi. But first plugged in with the different extension cord to the same gfi and done same thing. Went to another gfi and plugged in and all is working fine.

Gfi appears to have failed. Does anyone know which is a better brand to buy? I don't buy the cheap stuff. but I do buy the 20 amp ones.

Off to Menards in the morning.

Wayne

 

[TheDucks]

39 minutes ago, Wayne K said:

Thanks everyone, I seen the first couple of post earlier in the day and just got back in here and read the other ones. Took advantage of the warm weather to get finished up before the cold gets here.

Well thru the process of elimination.

# 1 changed controller out, same problem.

# 2 Pulled each channel connector apart and tried each channel, Same problem

# 3 went to shop and got longer extension cord so I could get to another gfi. But first plugged in with the different extension cord to the same gfi and done same thing. Went to another gfi and plugged in and all is working fine.

Gfi appears to have failed. Does anyone know which is a better brand to buy? I don't buy the cheap stuff. but I do buy the 20 amp ones.

Off to Menards in the morning.

Wayne

 

The 20A (5-20R) one is ONLY REQUIRED  if that is the only outlet on a 20A breaker. All 115V outlets (5-15R) can be used on a 20A circuit with multiple outlets on the branch circuit.

💡 If there are currently other 'down stream' outlets, you might change those to their own GFCI outlet. Downstream protected outlets will have wire on the terminals usually covered by yellow tape.

If you need advice on how to convert, ask.   Preferred: You will need 2 wire nuts  and about 1' of white and black 12Ga wire.  If the wire clamps are rated for 2 Wires, that is the less preferred (by electricians ) way.

IMHO Only use outlets that have screws (never the simple push in, no screw tightened after) . FWIW older houses had these on 20A circuits. Newer outlets will not allow 12Ga to be pushed in. You must use the screws)

As to brands: Eaton or Leviton 👍

 

[dgrant]

18 hours ago, k6ccc said:

Common belief, but incorrect.  A GFCI outlet or breaker does not care at all about the ground connection.  In fact a GFCI breaker does not have any connection to ground, and either will work fine on a 2 wire circuit (no ground).  What a GFCI outlet or breaker is looking for is that the amount of current on the hot and neutral wires are the same.  If they are different by more than about 5 milli Amps, the GFCI will trip.  The logic is that if the hot and neutral are not the same, then current is leaking somewhere.  It does not care where, only that it is leaking somewhere that it's not supposed to.  In most cases, that leak is to ground, but not always.  For example it is somewhat common practice (and perfectly legal in most situations) to have two 120 volt circuits that are on opposite phases to use a common neutral.  Can't do that if either circuit breaker is a GFCI because now you are getting neutral current from both circuit together on one wire.  Will trip the GFCI every time.

These days there are also Arc Fault Current Interrupters (AFCI), but that's a whole different discussion.

 

I didn't know that! I was pretty sure that is the way they use to be and I read up on them long ago too. So, I've learned something new. Thanks