GFCI and Drinking Fountains

[rjmeitner]

We have several new drinking fountains on GFCI outlets. The GFCIs are tripping regularly.

We replaced one GFCI with a standard outlet for testing. When operating the electric "push to drink" switches, a very brief current spike up to 2A appears on the equipment grounding conductor between the cord and the metal casing. The spike is too fast to see on the digital meter, but the meter catches it with a "max" record function. Measuring voltage between neutral and ground again picks up a brief but definite spike of a volt or two. I get the same kind of spike with the ammeter around the H and N leads, but not if I include H, N, and G.

The event is definitely linked to the operator switches. I wasn't able to tell if the same happens when the cooling fan kicks on, but based on reports of when these are tripping, I think it is probable.

Any ideas what is going on?

 

[celtic]

Is the unit bonded internally (N-G)?

 

[RayS]

I'm guessing some solenoid inrush current coupling into the other feed wires, or possibly(much less likely?) magnetically into the pipe/casing.

 

[Jim W in Tampa]

gfci not required unless in specs

 

[rjmeitner]

An N-G connection is possible; I'll have to check for continuity. If that were the case, wouldn't a portion of the running current also appear on the ground wire?

The GFCIs are specified, but we could change them out. Everything I've found on the net says the GFCIs shouldn't be tripping. I hate to just cure the symptom...

 

[celtic]

An N-G connection is possible; I'll have to check for continuity. If that were the case, wouldn't a portion of the running current also appear on the ground wire?

Possibly...BUT, a GFCI has a very low threshold (milliamps) over time...how will you be able to document it?
Instead of going through any major steps - like change the device to a non-GFCI device - ring out the cord...see if there is a N-G connection.