Minimum Voltage 120VAC GFCI

[grasfulls]

I am working on a job with a lighting control system. All of the outputs form modules to landscape lighting (some transformers, some direct loads) have been run through GFCI feed-thru devices rated 120VAC. All outputs were on dimmers (these are slowly being changed to relays unless they want to dim them). Does anyone know if the GFCI has a minimum voltage it must see?

There are multiple manufacturers, none with indicator lights, we are changing out the ones that seem to be nuisance tripping with COOPER VGFD20. We have found that MOST were actually tripping due to faults in the field, it is just cheaper to replace first. One stopped tripping when we moved the load to a relay output versus a dimmer output. Several are form water filled in-ground transformers - poorly installed I might add.

 

[iwire]

In my opinion having GFCIs on the load side of a dimmer is a code violation.

110.3(A)(7) and 110.3(B).

A GFCI is utilization equipment and supplying it with less than its rated voltage is a problem.

 

[CONDUIT]

Also in violation of 404.14(E)

 

[sparky8786]

The GFCI device needs to be installed before the dimmer. The GFCI is listed to operate on the 120 Volt Nominal System Voltage.

 

[SG-1]

The P&S brand that I tried worked down to 103 VAC. I was using an ETCON CT101 plug-in tester to trip it. I assumed the reason it stopped was that insufficient "fault" current was flowing through the tester, below the trip threshhold. I did not think to try the push button.

I agree with others it is a bad idea to use it, as described. You cannot expect it to operate.

 

[gar]

130919-1954 EDT

With a single sample of a Leviton I can both test trip and reset the GFCI down to 85 V, but not at 80 V. The calculated test current at 85 V is 5.7 mA.

That I can not reset the GFCI at 80 V means there is not enough current to pull-in the coil, part of the reset test, or the electronics does not function at this input voltage level. This is good circuit design because of the wide input range, but it does not mean the GFCI should be operated below its nominal rated voltage range.

.

 

[GoldDigger]

This is good circuit design because of the wide input range, but it does not mean the GFCI should be operated below its nominal rated voltage range.

In particular, it also should not be operated on a non-sinusoidal wave form, such as a modified square wave or a phase controlled (pulsed) sine wave from a typical dimmer.