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ProGrade, Certified Electrical Contractor
Category: Electrical
Satisfied Customers: 547
Experience:  28+ years exp. - installation, troubleshooting, & repair of commercial, & residential electrical systems.
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I'm researching the difference between 5mA and 30mA GFI

Customer Question

I'm researching the difference between 5mA and 30mA GFI protection at 480V. They want personnel protection and that's not possible. Wondering if 5mA is worth investing in
Submitted: 1 year ago.
Category: Electrical
Expert:  ProGrade replied 1 year ago.

5mA is for people protection, generally 30mA is for equipment. In US round fault protection is required on "solidly grounded wye electrical services over 150 volts phase -to-phase for each service disconnect rated 1000 amperes or more" NEC 230.95

Cooper has a discussion on their website search for Ground Fault Protection

Please let me know if you need more info. Thank you

Customer: replied 1 year ago.
This is not really what I'm looking for. The circuit is 20A 3Ph 480V with installed 30mA GFI. They want Personnel protection which is only available at 120V. They are wondering if 5mA is worth changing to
Expert:  ProGrade replied 1 year ago.

Thank you for the clarification. The only GFCI protection for general/personal protective use in the US is the standard GFCI Outlet or Breaker. In reading, there does not appear to be anything like this available in the US, not from Square D/Schneider and the likes anyway.

For your question, is it worth it? Consider looking in the mirror and asking yourself that question after someone is injured or worse, yes, in my opinion, it's worth it.

I also searcheD for Class A GFCI at 480V, does not produce any results

Customer: replied 1 year ago.
You misunderstood my question. This does not answer what I'm looking for. I will be requesting a refund. Sorry for the trouble.
Expert:  ProGrade replied 1 year ago.

The difference is 5mA is rated as personal protective devices Class A per the NEC. 30 mA protection is only for equipment protection.

Customer: replied 1 year ago.
At 480V 5mA is still only classified as equipment protection. Personal protection is only available for 120V circuits. The question is how much would they gain by changing 30mA GFI to 5mA GFI protection at 480V. It STILL only offers equipment protection with a slightly better trip time (and they want personal which isn't an option)
Expert:  ProGrade replied 1 year ago.

I agree, it's not an option for people protection at 480v. If other experts disagree, they will chime in.

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