Can I substitute GFPE with GFCI?

[zemingduan]

NEC 230.95 requires that "Ground-fault protection of equipment shall be provided for solidly grounded wye electric services of more than 150 volts to ground but not exceeding 1000 volts phase-to-phase for each service disconnect rated 1000 amperes or more. "

For example, we have a 3000A main service breaker for 480Y/277V 3ph 4w service. Can I specify GFCI breaker instead GFPE? GFCI has lower threshold amps and provide more protection to human that GFPE can't provide.

Thank you,

 

[jim dungar]

No.

Your main would trip often, as it is looking at all of the current to ground. It is not uncommon to have several amps of total 'leakage' current on a 3000A service.

Listed GFCI devices are not available for 480V systems

 

[infinity]

The requirement is to protect the equipment not humans. Besides humans will likely contact 120 volts so your GFCI protection at the 480 volt service won't do anything.

 

[winnie]

As far as code is concerned, your ground fault detection threshold can be as low as you want. If the customer demands it, you could use a 5mA ground fault detection threshold on your 480V 3000A service.

As a practical matter, you can't. The expected leakage current in a normally and correctly operating 480V system of just about any size would exceed 5mA. The tiniest of faults would trip your main.

The detection threshold for a 3000A 480V system will be in the hundreds or thousands of amps, not in the mA range needed for personnel protection.

Even if you really want GFCI level protection on the 480V systems in a facility, you would not do this on the main. You would divide the system up into numerous small GFCI protected subsystems.

Jon

 

[zemingduan]

Thank you very much for these information. It's very helpful. Is it common to specify GFCI for 3000A or 4000A main service breaker for 208Y/120V 3ph 4w service? I see many engineers and gears submittal specify GFCI and LSI breaker for 3000A or 4000A 208 3ph wye service. I don't know the reason/purpose to specify GFCI. I think NEC doesn't requires this.

 

[don_resqcapt19]

No.

Your main would trip often, as it is looking at all of the current to ground. It is not uncommon to have several amps of total 'leakage' current on a 3000A service.

Listed GFCI devices are not available for 480V systems

Listed Class A GFCI devices are not available for 480 volt systems, but listed Class C and D GFCIs are. Because UL calls them all GFCIs, the code has been working on clarifying that the typical applications of GFCI required in the code are Class A devices. In the 2023 code they added Special Purpose GFCIs, (SPGFCI), that are really Class C and D GFCIs for some applications in Article 680.

I expect that we will see expansion of the SPGFCI requirements in the 2026 code.

These devices have a trip level of 20 mA and require an additional conductor between the SPGFCI and the protected equipment. The conductor is used to verify the EGC to that equipment. If either the "ground check conductor" or the EGC become open, the SPGFCI will trip.

 

[hillbilly1]

I once had an electrician say “That’s a ground fault switchgear, you can touch the buss bar and it will trip”. Maybe after you catch fire! LOL!