Commercial Kitchen Ground-Fault

[dbowling]

According to the 2002 NEC 210.8(B.3) 15 and 20 amp 120 volt receptacles in non-dwelling kitchens are to be GFCI protected. We are consulting engineers for several chain restaurants. They are all having problems with the GF tripping on refrigeration equipment such as refrigerated prep tables in areas where the 2002 code has been adopted. This is causing a concern for health reasons above the nuisance of re-setting the ground-faults (whether they be receptacles or breakers.)

It is our understanding that the ground wire is used internally by equipment manufacturers (such as Delfield) and is wired in the defrost cycle of their equipment to the housing. The ground fault sensors are properly sensing the GF, but it is not an electrical hazard. This was a subject of many articles when the 99 code was issued for residential refrigerators and it was stated that you didn't want a GF on the refrigerator and it wouldn't be required since the receptacle was dedicated to the refrigerator.

Is there any one who knows more about this subject or has found an exception or solution to this rule?

 

[bphgravity]

Re: Commercial Kitchen Ground-Fault

Alot of people claim that refrigerators have GFI tripping problems, however it is my understanding that in order for a refrigerator to get a UL listing, it must not have a normal operating ground leak exceeding well above GFI trip ranges. Are you sure there is not another reason for the nuisance tripping and not really the refrigerators?

 

[txsparky]

Re: Commercial Kitchen Ground-Fault

One of the problems that I have seen with refrigerated prep tables is the drain becoming clogged and allowing water to back up to the level of the fans.

 

[tom baker]

Re: Commercial Kitchen Ground-Fault

There are no exceptions to the rule in the 2002 NEC. The proposals for the 2005 cycle will be avaiable soon, you can make a comment to support what will sure to be numerous proposals to change the requirement.
In Washington State we've addressed this issue on the local level by defining a kithen as " a countertop area used for food prep", hence your recpatacles for coolers do not have to be GFCI.

 

[hurk27]

Re: Commercial Kitchen Ground-Fault

bphgravity
The nuisance tripping of GFCI's are not being caused by a leakage of current to ground. But by the surge when the appliance is shutting down and it is caused by the fast current spike that will throw the hot and neutral out of balance which will cause the GFCI to trip. I have witnessed this even without a egc connected to the appliance.

 

[tom baker]

Re: Commercial Kitchen Ground-Fault

Hurk, I wonder if the newer types of GFCI's, now required under the 2003 revision to the UL GFCI standard will not nusicance trip? They have improved transient voltage protection.

 

[hurk27]

Re: Commercial Kitchen Ground-Fault

That is a good question. Maybe I can try to contact one of them to see if they implamented useing MOV's to block surges or something. In the past I had used MOV's to do this but I dont think it would of been code, but it did solved the tripping from a paddle fan duo-dehummer control that would spike the bath gfci, back before they were required to be on there own circuit.

 

[dbowling]

Re: Commercial Kitchen Ground-Fault

Wanted to say thanks to all of you that replied or commented. I liked the decision that Washington State made in using the residential definition for this situation.

One of our clients is testing a restaurant location using a higher ground-fault trip rating breaker (I believe a 30ma) to see if that would reduce the problem of the nuisance trips.

If anyone has any suggestions on presenting proposals to the Code Making Panel for either amending this current requirement or making a revised proposal for the next code cycle, I would appreciate the information.

 

[bill addiss]

Re: Commercial Kitchen Ground-Fault

For what it's worth, I submitted the following proposal myself:

Add an Exception to 210.8(B)(3):

Exception: A single receptacle or a duplex receptacle for two appliances located within dedicated space for each appliance that, in normal use, is not easily moved from one place to another and that is cord-and-plug connected in accordance with 400.7(A)(6), (A)(7), or (A)(8).

Substantiation:

There is often great concern about financial losses on perishable items that may result from 'False-Tripping' of GFCIs used on circuits supplying Refrigeration Equipment. Receptacles behind Refrigerators in Dwelling Units are not required to have GFCI protection, and there seems to be some awareness that incompatibility may exist in 525.23(B) where "Receptacles supplying items, such as cooking and refrigeration equipment, that are incompatible with ground-fault circuit-interrupter devices shall not be required to have ground-fault circuit-interrupter protection" Why shouldn't the same options exist for these Appliances in 'Other than Dwelling Unit' Kitchens?

Bill