gfci breaker vs gfci device

[forcebjj]

What is more reliable(faster) in tripping, a gfci breaker or actual gfci device? and having both is really double the protection? Heard something at work confused me a bit

 

[infinity]

They both should trip at the 4-6ma threshold required for Class A GFCI protection. You can use both on the same circuit.

 

[ramsy]

Magnetic trip breakers & current limiting fuses can operate faster than GFCI's, if the magnitude of the fault waveform is large enough.

GFCI circuitry also has a trip curve, and the UL specification for Class-A GFCI's disconnect speed is similar to inverse time circuit breakers, not necessarily faster.

 

[hbiss]

You can use both on the same circuit.

If you want to drive your customer nuts trying to figure out which tripped and why.

No reason or advantage to using both.

-Hal

 

[GoldDigger]

Magnetic trip breakers & current limiting fuses can operate faster than GFCI's, if the magnitude of the fault waveform is large enough.

GFCI circuitry also has a trip curve, and the UL specification for Class-A GFCI's disconnect speed is similar to inverse time circuit breakers, not necessarily faster.

Note that GFCI devices do not have any overall overcurrent protection, while GFCI breakers have that as their base before the GFCI trip is added.

 

[synchro]

What is more reliable(faster) in tripping, a gfci breaker or actual gfci device? and having both is really double the protection? Heard something at work confused me a bit

I wouldn't necessarily equate "more reliable" to faster tripping. Apparently some of the cheaper GFCIs (I assume receptacles and not breakers) don't follow the inverse time UL curve mentioned above, but are compliant as long as it trips faster than the curve. Quoting from the following link:

https://iaeimagazine.org/magazine/2...have-a-proactive-option-for-shock-protection/

UL 943 says that Class A GFCIs should have the inverse-time trip curve shown in figure 2 over a leakage current range of 6 to 264 mA, but some manufacturers of lower-priced Class A devices do not implement the curve because it makes the design more complicated, and instead use an instantaneous response that is lower than the quickest response required by the code just to pass testing. The UL curve is the absolute highest time response accepted but it is not restrictive. A device will fail UL testing if it responds to a fault slower than the curve suggests but will pass as long as the response time is less than the curve time. Too-quick response to transient ground-fault currents of low magnitudes will cause nuisance tripping; this is the main reason for not using residential type Class A GFCIs in industrial applications even where the line-to-line voltage is 240 V or lower and the system leakage is less than 6 mA.

 

[synchro]

Also, until very recently no GFCI breakers self-tested the SCR and solenoid inside the device, while this has been required for GFCI receptacles.

https://iaeimagazine.org/magazine/2017/09/05/its-time-we-update-ul-943-again/

 

[FionaZuppa]

"you" also need to test them on a regular basis
So, which one is easier to test, the item out in a locked panel, or the button right there on the counter?

For resi, closer to use is generally preferred, but some exceptions to that exist.