Electrician screening

[neoY]

Hey All,

I have had multiple electricians provide quotes to install a wall charger and one of them is saying that I need to upgrade the service to my house from 200A to 300 or 400A (which they can do). The rest of them did not bring this up as a concern with installing it.

The guy saying this is one from Tesla's electrician search list. I will be having another one from that list come in on Friday this week. I will update here what he says.

But wanted to post here to see if anyone else had this situation and any advise. The service to my house is 200A and I only have a electric dryer/washer and cooling HVAC. Rest of the appliances are gas. There are empty slots available in the exterior main breaker box. Thanks in advance for your responses.

 

[Jschoef]

6awg Non-metalic sheathed cable (of ANY KIND) is not permitted for a 48a charge rate/60a breaker. The issue is it's rated at 60c. at 60c it's only 55amps, and chargers require the cable to be rated at 125% of the circuit load. This means at 48a charge, your wire/breaker must be rated at 60a.

To get 60a rating with Non-metalic sheathed cable you must use 4AWG. The pictures do not look like 4awg. You need to have the wire replaced with 4/2 or run THHN (90c rated) in some form of conduit.

The main issue is the wire WILL get hot under charge. the hotter it gets the more resisitance, turnint it hotter, and if the breaker is too big it will never trip and you have a fire.

You can down-rate to a 32a charge (40a breaker) or 40a (50a) breaker and use your current cable. There is a reason you get a permit for this stuff. If you had one, you wouldn't have passed inspection.

All correct for sure! It’s the right way to do it. Lots of electricians and DIY are using 6-2 Romex though without issues…but it is wrong.

 

[neoY]

My electrician said “It’s #6. That’s what the charger requires. It’s good for 125% of the charger output”

The county inspector passed the install today.

Thanks to everyone’s feedback I will be limiting the charge current on the app to 32 amps or lower to be safe.

 

[Jschoef]

My electrician said “It’s #6. That’s what the charger requires. It’s good for 125% of the charger output”

The county inspector passed the install today.

Thanks to everyone’s feedback I will be limiting the charge current on the app to 32 amps or lower to be safe.

I think you just need to lower it to 44amps. You could (within the firmware) permanently lower it to a 50amp breaker. I am replacing my Romex today though as there are times I need a fast charge and I don’t want to forget a setting.

If you wanted to complain about the cable not making code, the cable needs to be 90 deg C for conductors, which it clearly says in the instructions, and the spec sheet says clearly that it’s rated for 60 deg C.

 

[Rocky_H]

If you wanted to complain about the cable not making code, the cable needs to be 90 deg C for conductors, which it clearly says in the instructions, and the spec sheet says clearly that it’s rated for 60 deg C.

That part is unfortunately confusing and misleading. The wall connector wire lugs and residential breakers aren't even rated for 90 degree C connections, so you're not going to be using those rating levels anyway. But what you're referring to, inside Romex cable, those individual wires ARE actually 90 degree C rated conductors...individually. So that does fit what the installation manual says. But when used as a bundle like that, you have to fit the installation conditions and rating levels of the 60 degree condition of the Romex cable as a whole. People make this more complicated than it should be. Code covers this stuff, so whatever level of circuit you are going to use, whether it's 30, 40, 50, 60, or whatever, just comply with code for that level of circuit. That covers all of these things.

 

[Jschoef]