Electrician installed wall connector using Romex 8/3 + 60A breaker

[Rocky_H]

Yes, people try to bring up the "Round up rule" frequently, and we try to never bring it up here, because people ALWAYS use it wrong. Those are still 52A or 53.75A rated circuits, and that works with 55A rated Romex 6 gauge. What people get wrong all of the time is they think that rounding up the breaker to 60A magically waves a wand over the whole entire circuit and gives everything a full 60A rating and lets them use 48A continuous draw, and that's simply wrong.

 

[davewill]

It would be nice if Tesla would just update the wall connector firmware to allow selecting a 55a circuit with 44a charging. Even better if they would update their install instructions to list the common wire types and what amperage they support when used with the wall connector.

 

[Magnetic Flux]

Yes, people try to bring up the "Round up rule" frequently, and we try to never bring it up here, because people ALWAYS use it wrong. Those are still 52A or 53.75A rated circuits, and that works with 55A rated Romex 6 gauge. What people get wrong all of the time is they think that rounding up the breaker to 60A magically waves a wand over the whole entire circuit and gives everything a full 60A rating and lets them use 48A continuous draw, and that's simply wrong.

I don't disagree with you at all, I was trying to clarify when that "round up" rule is applicable since people are often referencing that incorrectly. I stated that the Wall Connector install does not meet those requirements in my earlier post.

The continuous rating circuit requirement (125% multiplier) applies to BOTH the breaker (section 240) and the conductors (section 210). 48A at 125% is 60A. The conductor and breaker MUST meet that requirement at a minimum.

I agree with several commenters that a sticky thread should be added that simply lists the code requirements and facts from reputable sources/members to prevent the endless discussions on this topic. It could also be used for the members to provide direct reference for any installers so they can look up the code sections themselves.

I think it is technically against the copyright of the National Electrical Code for me to clip the exact sections and put them in a thread, but we could copy and paste the text verbatim with the specific year referenced. Then anyone could read it themselves and also open their own code book to follow the sections if they wanted to see.

 

[SageBrush]

I agree with several commenters that a sticky thread should be added that simply lists the code requirements and facts from reputable sources/members to prevent the endless discussions on this topic. It could also be used for the members to provide direct reference for any installers so they can look up the code sections themselves.

I think it is technically against the copyright of the National Electrical Code for me to clip the exact sections and put them in a thread, but we could copy and paste the text verbatim with the specific year referenced. Then anyone could read it themselves and also open their own code book to follow the sections if they wanted to see.

I thought about writing a FAQ but I decided not to because people would use it as a cookbook and end up with NEC violations. This is particularly risky with NM-B and attic runs.

I don't live in an area with attics so I had to Google summer attic temperatures. The search said up to 60 - 70C (!!!).
At those temperatures, the NEC derates the 75C column to between 1/3 .... 0. Meaning at best 22 Amps; at worse, do not use.

 

[SageBrush]

home inspectors, especially, are not well versed on nuances in the electrical code.

And even if they are, are they going to ask for the TWC Amp setting ? Or whether the run goes through the attic, and whether the attic is ventilated ?

 

[sleepydoc]

It would be nice if Tesla would just update the wall connector firmware to allow selecting a 55a circuit with 44a charging. Even better if they would update their install instructions to list the common wire types and what amperage they support when used with the wall connector.

What would be even better is if the NEC published specific guidelines for wiring EV charging circuits.

 

[sleepydoc]

I thought about writing a FAQ but I decided not to because people would use it as a cookbook and end up with NEC violations. This is particularly risky with NM-B and attic runs.

I don't live in an area with attics so I had to Google summer attic temperatures. The search said up to 60 - 70C (!!!).
At those temperatures, the NEC derates the 75C column to between 1/3 .... 0. Meaning at best 22 Amps; at worse, do not use.

It turns out that there are a lot of nuances to wiring circuits and it’s not straight forward or simple. Wow!

 

[SageBrush]

What would be even better is if the NEC published specific guidelines for wiring EV charging circuits.

Article 625

 

[SageBrush]

It turns out that there are a lot of nuances to wiring circuits and it’s not straight forward or simple.

I would say it a bit differently: sometimes it is simple and (relatively) straightforward.

Sometimes. Perhaps even most of the time.

 

[dhrivnak]

Glad to hear that I was right. I've shut off the breaker for now, and will wait for him to come fix.

You could drop the amps to 32 and be safe with the wire. I would still get him to change it as he is wrong. But you should be fine at the lower amperage until it gets changed.

 

[Ping123]

I'm not following here. Is the NM-B in a wall ? If it is tacked on to the drywall, you get to take it down and start again. I'd like to see a photo of what you have at the moment.

By the way you have another option here if the NM-B is correctly installed: keep the 8/3, change the breaker to 40 Amps, and run power at 32 Amp continuous. I'll leave it to you to decide how much to pay the "electrician."

--
Addendum: I have no idea about TX. In NM we have licensed electricians and handyman. The latter are not allowed to install conduit. I don't know if they are restricted to a maximum AWG wire, but it seems likely.

Addendum #2, general FYI:
A branch circuit (BC) used for EV charging is continuous use. The wire and breaker ratings must be 125% of the maximum power draw. NM-B wire ratings are per the 60C column in table 310.16 of the NEC. Corrections and adjustments (e.g., due to high temperature) are per the 90C table but that is probably not in play here since the 60C requirement will likely be the deciding factor. Very hot places may end up with a different result.

Thank you so much for your insights and comments. The distance between my electrical panel and newly installed wall connector is only 2 feet. Is there any issue running the conduit and 8/3 cable just 2 feet long?

 

[SageBrush]

Thank you so much for your insights and comments. The distance between my electrical panel and newly installed wall connector is only 2 feet. Is there any issue running the conduit and 8/3 cable just 2 feet long?

I'm not sure what you are asking, but the 'nipple' aka 24" rule allows two things:

1. Conduit fill can be up to 60%
2. Ambient Temp derating is not required for that section

If your "8/3 cable" is NMB then you are limited to 32 Amp continuous and you would place a 40 Amp breaker. The same would be true for a longer run.
Some people think that short runs allow more Amps but this is not correct.

 

[sleepydoc]

Article 625

I re-read section 625 (it’s been a while since I read it) and it does indeed have more detail than I remember. Part of the problem with code books like the NEC is that a lot of the information is indirect or implied, or convoluted, refers to another section which in turn refers to yet another section.

Now, this is the nature of rule and code books, and I would expect any licensed electrician to be accustomed to interpreting them, but it does make them rather obtuse and also makes it difficult for the lay person to check to see if the ‘professional’ they hired is out to lunch.

 

[SageBrush]

I re-read section 625 (it’s been a while since I read it) and it does indeed have more detail than I remember. Part of the problem with code books like the NEC is that a lot of the information is indirect or implied, or convoluted, refers to another section which in turn refers to yet another section.

Now, this is the nature of rule and code books, and I would expect any licensed electrician to be accustomed to interpreting them, but it does make them rather obtuse and also makes it difficult for the lay person to check to see if the ‘professional’ they hired is out to lunch.

For sure ! And that is before we mention the jargonese, the stilted language, and the lawyerly prose. I think it takes most electricians years before they are comfortable reading the NEC, and then for the most part only those Articles in which they have practical experience.

The 2023 NEC is published. One change I like to Article 625 is GFI: No more location exceptions. A receptacle used for EV charging gets a GFI. Nice and clear.

 

[Ping123]

I'm not sure what you are asking, but the 'nipple' aka 24" rule allows two things:

1. Conduit fill can be up to 60%
2. Ambient Temp derating is not required for that section

If your "8/3 cable" is NMB then you are limited to 32 Amp continuous and you would place a 40 Amp breaker. The same would be true for a longer run.
Some people think that short runs allow more Amps but this is not correct.

Thank you! I just got it working last night. My cable run is only 3 feet long. The connector is literally 2 feet away from the electrical panel or 40 amp circuit breaker.

 

[Ping123]

Thank you! I just got it working last night. My cable run is only 3 feet long. The connector is literally 2 feet away from the electrical panel or 40 amp circuit breaker.

 

[EvJourney]

Yeah that’s dangerous.

Branch Circuit Conductors and Ground Wire
NOTE: Circuit breaker size is programmed during the commissioning process. See Commissioning Procedure on page 28 for details.
NOTE: Some Tesla vehicles may draw less current than the max output. Actual charging rate depends on Wall Connector output and onboard charger in the vehicle.
• If installing for less than maximum power, refer to local electrical code to select correct conductors and ground wire size that are suitable for the chosen circuit breaker.
• If installing for maximum power, use minimum 6 AWG, 90° C-rated copper wire for conductors.
NOTE: Upsize conductors if necessary.
• For sites with multiple Wall Connectors, each Wall Connector must have its own branch circuit with L1,
L2/N, and Ground.
• COPPER WIRE TERMINATIONS ONLY for landing in Wall Connector wirebox terminals. Conductors can be stranded or solid.
• Hardwire branch circuits to disconnects or circuit breakers. Do NOT install cord-and-plug type connections.
• For outdoor installations, use watertight fittings when securing feeder wires to the wirebox.

 

[Rocky_H]

What would be even better is if the NEC published specific guidelines for wiring EV charging circuits.

It already has as much specificity as it needs. It seems a lot of times people try to make it more complicated than it is. The wire needs to meet the rating of the circuit. And there is one question: Is it a continuous load or not a continuous load? NEC stated that absolutely clearly that EV charging must always be treated as a continuous load. And that's that. There isn't anything else that's unique or complicated about it being an EV--it's just a continuous load appliance, and you use properly rated wire for it.

Yeah that’s dangerous.

Uhh...what's dangerous? You're on page 6 of a thread and didn't quote or reference anyone's statements.

 

[EdCBC]

You might be able to pull the permit yourself. Depends on your jurisdiction. I think you have to give him a chance to fix it at this point, just make sure someone besides him inspects the work.

Of course if he gives you any more guff, demand a full refund and have it done right by someone else.

Consider switching to a 40 amp breaker, if your electrical inspector will accept that with the 8/3 cable. My 30 amp system will give a 20% to 90% charge over night. I see no advantage to having a higher charge rate for one EV. If you need to charge two EV's on the same day the 60 amp system would make sense.

 

[dafish]

An actual electrician did that? Wowza. Might want to have the conduit connect to your box corrected. Were we friends we'd be having a little chat over a beer about how to select service providers better. The guy you have isn't good enough to be called a hack.

And for that little distance? I'd for sure fix it. Don't forget temp rating of breakers, cause it's certain your guy ain't lookin.