GFCI 208v, no neutral

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mefalk55

Member
Hello Guys, I've got a question on GFCI, 208 volt, single phase. Feeding a dishwasher in a commercial setting. Can we use a GFCI breaker on an appliance that has no neutral wire in the circuit? If so, how is the current measured? Between the 2 hot legs? If there is a variation of 5 ma between the the 2, should'nt the GFCI still work without a neutral? One of my appliance guys got shocked. Water got in the control box. I want to put in a GFCI without having to run a new cable. I have two hot legs and a groung existing. The contractors did the install and used a standard 2 pole, 30 amp breaker. I took this dishwasher out of service until I get an answer from the FORUM. I've always trusted you for direction. Appreciate your help!
 

iwire

Moderator
Staff member
Location
Massachusetts
Yeah you can do it. You will have to connect the neutral pigtail on the breaker to the neutral bar.


Just a side note or two.

GFCIs do not prevent shocks, I would focus on preventing the shock.

If a person was to contact both legs of the 208 the GFCI would see that as a normal load and would not trip.
 

mefalk55

Member
Thanks. Only trying to prevent water shorts. My guys know better than to work on units hot. Water shorts to ground are my concern. My guys are aware of lockout tagout when working on equipment. Thank you!
 

hillbilly1

Senior Member
Location
Atlanta,Ga
Occupation
Field coordinator/ technical support
Thanks. Only trying to prevent water shorts. My guys know better than to work on units hot. Water shorts to ground are my concern. My guys are aware of lockout tagout when working on equipment. Thank you!

If the unit is properly grounded and they were not working on it hot, I don't know how they got shocked? If they were shocked by touching the frame of the unit and it is properly grounded, the current came from some where else and was returning through the grounded frame. Ground fault protection of the dishwasher circuit will not prevent this kind of shock.
 

LarryFine

Master Electrician Electric Contractor Richmond VA
Location
Henrico County, VA
Occupation
Electrical Contractor
If there is a variation of 5 ma between the the 2, should'nt the GFCI still work without a neutral?
Yes. As long as all circuit conductors pass through the GFCI, it doesn't matter whether one of the is grounded. As stated above, the GFCI's neutral pigtail must be connected.
 

Electric-Light

Senior Member
If the unit is properly grounded and they were not working on it hot, I don't know how they got shocked? If they were shocked by touching the frame of the unit and it is properly grounded, the current came from some where else and was returning through the grounded frame. Ground fault protection of the dishwasher circuit will not prevent this kind of shock.

GFCI will sense any asymmetry. If the control becomes wet and tech touches it and current flows to ground, GFCI will respond assuming it returned to ground. It is basically a mA clamp-meter with both sides of wires in it so that normal flow cancels out. Any current that doesn't complete a round trip on the loop creates reading on GFCI.
 
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