HPWC ground wire gauge

[ACAG]

I am installing the HPWC with a 60 amp breaker and using THHN 6 gauge wire for my hot legs. What gauge should I use for the ground wire... I was going to use 10 gauge THHN wire?

 

[mongo]

I am installing the HPWC with a 60 amp breaker and using THHN 6 gauge wire for my hot legs. What gauge should I use for the ground wire... I was going to use 10 gauge THHN wire?

That appears to be correct per NEC:
Equipment Grounding Conductor Table 250-95

HPWC installation instructions do not call out full sized ground, like some other appliances (hot tubs) do.

 

[Nogasmn]

I used 4 awg wire for my install and the ground wire that was bundled was 8 awg. So 10 awg will be ok. How long of a run that you are using 6 awg for a 60 amp set up?

 

[ACAG]

I used 4 awg wire for my install and the ground wire that was bundled was 8 awg. So 10 awg will be ok. How long of a run that you are using 6 awg for a 60 amp set up?

40 to 50 feet......what size breaker did you use for your install?

 

[Nogasmn]

I used a 60amp breaker. After plugging in your run distance into a online wire size calculator, its says you need to use 4awg wire not 6awg. Have you already purchased the wire? I made the mistake of buying off amazon and since it was a cut to length purchase by the time I realized my mistake I couldn't return it. I could have saved another ~$100 if I had got the wire from Lowes.

 

[ACAG]

I checked with an online calculator for wire size and run (please see pictures below)... With both a 100 ft run and 50 ft run, giving me results of using a 8 gauge wire and a 6 gauge wire, respectively.

 

[MrMassTransit]

My HPWC uses 10 gauge for the ground. The run from the panel (which at the service entrance, practically) is about 80-90 feet. However, my HPWC is on a 30 amp breaker because I have 100 amp service (condo building). The hot wires are 8 gauge.

 

[ACAG]

Also, can both lines of a 240 volt circuit be the same color... i.e. Black?

 

[JamstationP85D]

The Tesla wall connector I have doesnt require a Neutral so I just capped the 3rd 6 gauge cable. The ground wire in the Romex 6/3 looks to be about 8-10 gauge. The receptacle inside the Tesla wall charger could barely even handle that size.

 

[mongo]

Also, can both lines of a 240 volt circuit be the same color... i.e. Black?

Yes.

 

[Sophias_dad]

BTW, I wouldn't trust that calculator at all.... #8 in conduit is never allowed to carry 60 amps. Regardless of whether its in romex or conduit, and even if you ignore the 75c rating of the HPWC's connectors.

Ampacity Charts - Cerrowire

Note that the ratings on that page are without regard to distance... that is, you need to find an appropriate calculator to tell you if the losses are acceptable for a given length...

https://www.southwire.com/calculator-vdrop

 

[ACAG]

I used a 60amp breaker. After plugging in your run distance into a online wire size calculator, its says you need to use 4awg wire not 6awg. Have you already purchased the wire? I made the mistake of buying off amazon and since it was a cut to length purchase by the time I realized my mistake I couldn't return it. I could have saved another ~$100 if I had got the wire from Lowes.

How long was your wire run?

 

[Sophias_dad]

How long was your wire run?

https://www.southwire.com/calculator-vdrop

For 3% drop on 6AWG carrying 48 amps(its really carrying 48 amps, even though the THHN has to be rated for 60), you can go 169 feet overall(bidirectionally, pair of parallel conductors)

Interestingly, that calculator says the 6AWG won't take 60 amps... they must be assuming Romex/60c ratings, which I'm pretty surprised they would leave as an assumption.

 

[doghousePVD]

Also, can both lines of a 240 volt circuit be the same color... i.e. Black?

I think it can be, but suggested practice is one black, one red. White is definitely verboten.

 

[Sophias_dad]

I think it can be, but suggested practice is one black, one red. White is definitely verboten.

White is allowed, but you need to put some colored(not white, grey, or green) electrical tape near each end of it, so the person to next screw with it knows it might be live.

Its a little dated, but here's a reference.

https://www.ecmweb.com/national-electrical-code/qa/article/20890543/stumped-by-the-code

Note: upon rereading this, it's really intended for a cable like romex where the conductors are already built in and not changeable, not THHN in conduit.

Yes, two blacks should be fine. Black and red would be conventional, but not important.

 

[Nogasmn]

How long was your wire run?

75 feet.

 

[ACAG]

Thanks for all the input. I decided to go with 4 gauge THHN wire and 8 gauge THHN ground in 1 inch PVC schedule 40 conduit, to make pulling the wire easier. Luckily I can return the smaller wire to Home Depot.

 

[gogojoey123]

The gloss black HPWC is back in stock at Tesla Store, for anyone interested.

 

[Nogasmn]

Thanks for all the input. I decided to go with 4 gauge THHN wire and 8 gauge THHN ground in 1 inch PVC schedule 40 conduit, to make pulling the wire easier. Luckily I can return the smaller wire to Home Depot.

Perfect! Make sure you add like 10-15% extra length in wire. Take your time and it will be an easy project.

 

[ACAG]

Perfect! Make sure you add like 10-15% extra length in wire. Take your time and it will be an easy project.

Did you have any problem getting the 4 gauge wire in the terminal block on the HPWC? I was planning on using ferrules to make it easier.... Also I will be entering the HPWC from the bottom.