EV Charger

[nizak]

I’m sure this has been discussed here before but would like clarification.

I’m installing a Tesla Gen3 charger in a residence.

Product sheet shows 60 amp breaker and lists maximum output at 48 amps.

The 60 amp circuit satisfies the 125% requirements for continuous duty.

#6 NM cable @60deg allows 55 amps. Next size up circuit breaker is 60 amp.

Is the #6 NM cable code compliant to use in this application? If not, why.

This is a single charger with no other loads associated with the dedicated circuit.

Thanks

 

[goldstar]

From my recollection I believe 6/2 MC is the correct cable to use for this EV charger. You'll have to refer to the Tesla specs as well. I don't believe this unit requires a neutral.

 

[retirede]

No, NM is not compliant. The wire must have an ampacity of 125% of the continuous load (48A), so in this case, 60A.

I agree, no neutral for this and most EV chargers.

 

[nizak]

No, NM is not compliant. The wire must have an ampacity of 125% of the continuous load (48A), so in this case, 60A.

I agree, no neutral for this and most EV chargers.

So the ampacity rating of 60amps trumps the next size up circuit breaker exception?

 

[retirede]

So the ampacity rating of 60amps trumps the next size up circuit breaker exception?

The next size up can be used if the conductors are sized to handle the connected load. In this case, sizing the connected load results in 60A.

 

[jaggedben]

So the ampacity rating of 60amps trumps the next size up circuit breaker exception?

Yes.

Strictly speaking it's the 'required circuit current' of 60amps that's doing the trumping.

 

[nizak]

Yes.

Strictly speaking it's the 'required circuit current' of 60amps that's doing the trumping.

Thanks much. All replies appreciated

 

[electricmanscott]

This exact scenario has been discussed in the MH code seminar I'm at right now.

 

[wwhitney]

And I would say the NEC rules are overly conservative in this case. If 60C #6 Cu with a 55A non-continuous load can be protected safely at 60A, why can't the same conductor with a 48A continuous load be so protected? The wire itself is good for 55A continuous, it's just the OCPD that is the weak link, as well as whether the OCPD protects the wire.

Basically 215.2(A)(1)(a) and 210.19(A)(1)(a) should be deleted. Then 215.3 / 210.20(A), along with 240.4, will give almost the same results, with the exception that 240.4(D) can be used in the above situation.

Cheers, Wayne

 

[Alexis]

If I may bring this topic again.

I belive 6/2 wouldn't be compliant, singe whine neutral wire cannot be reindentified. Only 4awg and largen can. Would I be connect in this? Hate to waste copper, but the only right way here would be 6/3

 

[wwhitney]

I belive 6/2 wouldn't be compliant, singe whine neutral wire cannot be reindentified. Only 4awg and largen can. Would I be connect in this? Hate to waste copper, but the only right way here would be 6/3

That is not what NEC 200.7(C)(1) says. You can reidentify the white wire of a cable assembly in any size.

Reidentifying individual conductors pulled in conduit is what is restricted by size.

Cheers, Wayne

 

[TwistLock]

Then is #6 NM with 60 A breaker allowed as long as you set 55amp max (or lower) in EVSE installer app and place a label next to breaker ?

 

[jaggedben]

Then is #6 NM with 60 A breaker allowed as long as you set 55amp max (or lower) in EVSE installer app and place a label next to breaker ?

55 amps needs to be the calculation after adding the 125% continuous factor. So if you can tell the EVSE that the breaker is 55A, or tell it to allow max 44A or lower actual max current, then yes, it's allowed.

 

[Fred B]

The last Tesla I installed required by MFG instruction an insulated Grounding conductor that in of itself would prohibit the use of NM. I ran a conduit sized to allow for a neutral to be added if needed. But I believe you can run 6/2 MC as it has an insulated grounding conductor and the neutral being a cable assembly can be reidentified.

 

[Joe Villani]

From my recollection I believe 6/2 MC is the correct cable to use for this EV charger. You'll have to refer to the Tesla specs as well. I don't believe this unit requires a neutral.

Unless things changed, in NJ you are permitted to use #6 nm cable for a 48 amp charger.

However I agree with you regarding the 6/2 mc.

 

[retirede]

Unless things changed, in NJ you are permitted to use #6 nm cable for a 48 amp charger.

It would be interesting to see how they amended the code to allow that.

 

[jaggedben]

It would be interesting to see how they amended the code to allow that.

Yeah I'm doubtful that's correct. Someone's just getting away with it, perhaps.

 

[Joe Villani]

Yeah I'm doubtful that's correct. Someone's just getting away with it, perhaps.

See Pages 13 and 14.

 

[LarryFine]

See Pages 13 and 14.

 

[infinity]

It wouldn't be the first the DCA made an interpretation that was incorrect.