60 Amp Receptacle?

[retirede]

The Tesla level 3 wall charger advises against installing Gfci protection because it is already built in to the unit

Which is not an issues since it’s hard-wired. The problem arises when the EVSE is cord and plug & you’re on the 2020 NEC.

 

[synchro]

I think the issue with the gfci protection, is the charge controller has built in gfci, which self tests, and may nuisance trip external gfci if so installed.

I'm not sure why a GFCI inside of a charge controller would trip an external GFCI that feeds it when the internal GFCI performs a self-test. This is because the internal GFCI has access to both its line and load side conductors. It can therefore create a leakage current that flows between the line and load sides of the GFCI (and which therefore bypasses the CT within the GFCI) to implement its self-test function. As a result no actual ground fault current to the EGC is necessary to do a test, unlike a plug-in GFCI tester which does not have access to the line side of the GFCI and therefore must create a leakage current to the EGC to do its tests. That's not to say that there is no charge controller which uses a leakage current to the EGC for testing. But I'd be surprized if that was the case because no GFCI breakers or receptacles that I'm aware of do that.

However, there could certainly be other things within the charge controller that might trigger an external GFCI. And in any case, I appreciate hearing any and all ideas.

 

[wwhitney]

I think many EVSEs do a "EGC assurance" test that involves intentionally leaking some current to ground. Older ones may have used enough current to trip a GFCI; I would think newer ones would be better designed, unless the purpose of the EGC assurance test can't be satisfied with under 4ma.

Cheers, Wayne

 

[hillbilly1]

I'm not sure why a GFCI inside of a charge controller would trip an external GFCI that feeds it when the internal GFCI performs a self-test. This is because the internal GFCI has access to both its line and load side conductors. It can therefore create a leakage current that flows between the line and load sides of the GFCI (and which therefore bypasses the CT within the GFCI) to implement its self-test function. As a result no actual ground fault current to the EGC is necessary to do a test, unlike a plug-in GFCI tester which does not have access to the line side of the GFCI and therefore must create a leakage current to the EGC to do its tests. That's not to say that there is no charge controller which uses a leakage current to the EGC for testing. But I'd be surprized if that was the case because no GFCI breakers or receptacles that I'm aware of do that.

However, there could certainly be other things within the charge controller that might trigger an external GFCI. And in any case, I appreciate hearing any and all ideas.

I have been able to trip a gfi in series when using the test button, and it trip the one in front of it, so I think it depends on the manufacturers design.