208 Volt GFCI, commercial use

[mefalk55]

Hello all.... I need some basic training here. My backround has been stricktly Industrial Electrician. I have been doing pretty well lately adjusting to the change to Commercial Electrician. And I must put a word out there to all of you for your help solving some of my problems. I have been working with GFCI breakers on the 120V, single phase level. I disconnected an existing 208V, 30A breaker with the intent to reuse it. I kinda went a little numb when I saw that the plug did not have a neutral connection, just ground, black and red wires. The neutral was not connected to the appliance at all. Please give me the word on what is actually measured, and between what conductors, in order for this GFCI to sense a fault. Thanks Again, Mefalk:grin:

 

[peter d]

A 2 pole GFCI circuit breaker has all three load side wires running through a current transformer (L1, L2 and N.) If there is an imbalance between L1 and L2 and between both lines and neutral, then the GFCI mechanism will trip.

Therefore, a load side neutral connection is not required. (However, the pigtail neutral on the GFCI breaker itself must be connected for the internal electronics to operate even without a load side neutral connection.)

 

[JohnJ0906]

A 2-pole GFCI breaker measures the current on load hot A, load hot B, and load neutral. If it senses an imbalance of 5 milliamps or more, it trips.
However, there is no need for the load neutral to be used. The GFCI will operate perfectly fine without it.
For instance, I just wired a 240v hot tub, with a 50 amp GFCI breaker. The hot tub did not require a neutral, so I hook up the breaker neutral pigtail to the neutral bar, and leave the load terminal empty.

 

[infinity]

Keep in mind that many commercial installations use GFPE circuit breakers which have a trip rating of 30 ma. These cannot be used where a 4-6 ma trip, class A GFCI breaker is required.

 

[mefalk55]

GFCI 208V commercial

GFCI 208V commercial

Thank you all for the help. I hooked up the DP GFCI 208V breaker to the Espresso machine and everyone is happy. I did not want an unsafe electrical circuit. I am sure that it will sense any fault to ground and trip as engineered. Thanks again. mefalk55

 

[hardworkingstiff]

(However, the pigtail neutral on the GFCI breaker itself must be connected for the internal electronics to operate even without a load side neutral connection.)

Peter, do you know why that is?

(not challenging you, just trying to learn)

 

[jim dungar]

Peter, do you know why that is?

(not challenging you, just trying to learn)

It is for the test button. The test button connects a small resistor from the load side of a "line" conductor to the line side side of the neutral conductor.

 

[mefalk55]

Gfci 208v

Gfci 208v

The Neutral was connected to the neutral bus. No load on this line. Must be sensed to any ground. Grounded Conductor or Ground Safety. Thank you for your help.