While awaiting delivery of our new Model 3 Performance, we had an electrician install a 14-50 outlet. He ran approximately 25' of individual 8ga wire to a 40A breaker. I was expecting a 50A breaker. Should I have him swap it to the larger size, or should there not be an issue drawing 32A. I understand the 80% rule, but wanted to make sure I wouldn't need to reduce the charging draw to less than 32A.
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14-50 requirements
- Thread starter recreationman
- Start date
While a 50A breaker is ideal for a 14-50 outlet, the 40A breaker you have is acceptable for your setup. Using the 80% rule, with a 40A breaker, it's safe to charge your car at up to 32 Amps (40A x 80%). This should provide sufficient charging speed for most needs.
It's exactly what I have for 32amps, a 40amp breaker.
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E90alex
Active Member
That is fine for the mobile connector since it draws a max of 32 amps and therefore requires a 40 amp circuit.
Just don’t use anything else on that outlet that will try to pull more than 32 amps. Probably should put a label with 240V 40A on the cover of the outlet if the electrician doesn’t already do that.
Just don’t use anything else on that outlet that will try to pull more than 32 amps. Probably should put a label with 240V 40A on the cover of the outlet if the electrician doesn’t already do that.
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Thank you for the quick response! I shall now pay the electrician
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I have been using 32amp for close to 12 years now. I have a level 2 charger installed from 2012 on it. Been a long time. They will increase the charge if you increase the cost of materials. Changing the wire gauge so it can carry higher current for 50amp breaker.
It really is up to you. For mines, it still going strong.
It really is up to you. For mines, it still going strong.
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Weirdly there’s no actual code requirement for the circuit to match the outlet’s max rating. You can be code compliant with 14awg wiring on a 15A breaker with a 14-50 outlet as long as it’s the only outlet on the circuit.
Sounds like your guy ran 8awg thhn wire so you should be able to use a 50a breaker if you want. But for the purpose of the UMC, it makes no difference.
Sounds like your guy ran 8awg thhn wire so you should be able to use a 50a breaker if you want. But for the purpose of the UMC, it makes no difference.
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He installed a Leviton even though I sent him a picture of Bryant plug. Still somehow miscommunicated. Anyhow, I swapped the Leviton for Bryant. Am not sure why 40A went instead of 50A.
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I had sent an enquiry to Tesla several days ago and wouldn't you know it, after I posted y question, I received their reply:
"Thank you for contacting Tesla Energy Customer Support. I will be glad to assist you with your questions regarding the outlet install for the Mobile Connector.
The breaker should be 50amps, wired with 6 gauge copper, and pulling 240v. I hope this helps."
"Thank you for contacting Tesla Energy Customer Support. I will be glad to assist you with your questions regarding the outlet install for the Mobile Connector.
The breaker should be 50amps, wired with 6 gauge copper, and pulling 240v. I hope this helps."
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Presumably you are going to use the Tesla Mobile Connector to charge? If so, that install with a 40A breaker will work just fine since the mobile connector can only draw 32A anyways. Ignore those that say to swap in a 50A breaker, it isn’t needed and isn’t necessary. And indeed we don’t know what kind of install he did, whether he used NM-B or THHN in conduit since your posts are ambiguous.
Good call on using a Bryant receptacle.
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My apologies for the ambiguity. When I described the wires as pulled individually, it was the best way to describe that I could come up with. I have now been educated on differences between NM-B and THHN. No NM-B pulled, it was THHN. I'll leave the breaker as is. Thanks for your response!
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davewill
Active Member
In that case, you do have the option of upsizing the breaker to 50a. I wouldn't do so until and unless I anticipated needing the extra capacity. For example, if you wanted to plug in an RV, or wanted to wire in a wall connector and charge at 40a instead of 32a.
I've been using a 30a EVSE on a 40a circuit (using a 6-50) for a dozen years at this point. In my case, the wiring is not capable of more, and I've never had any need for more. When I put in a second outlet for a second car a few years back, I sized the wire for 60a, and put in a 50a breaker with a 14-50, but only as a future proofing strategy. I still only charge at 32a on that circuit.
The only reason I didn't do that the first time is that I owned a LEAF that could only charge at 16a and the 40a circuit seemed very future proof...as indeed it has proved to be.
I've been using a 30a EVSE on a 40a circuit (using a 6-50) for a dozen years at this point. In my case, the wiring is not capable of more, and I've never had any need for more. When I put in a second outlet for a second car a few years back, I sized the wire for 60a, and put in a 50a breaker with a 14-50, but only as a future proofing strategy. I still only charge at 32a on that circuit.
The only reason I didn't do that the first time is that I owned a LEAF that could only charge at 16a and the 40a circuit seemed very future proof...as indeed it has proved to be.
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Just for what it's worth, the Tesla Wall Connector will pull up to 48 amps using a 60amp circuit/breaker.
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ATPMSD
Active Member
Also It is cheaper!
Mobile Connector $250, GFCI breaker $150, Hubbell or Bryant outlet $80, Cable organizer $35 = $515
Wall Connector $450, standard breaker $15 = $465
Of course your prices may vary.
The wall connector supports any 240v circuit from 15a all the way up to 60a and is connected to the internet, it gets firmware updates and you can add it to your Tesla app.
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bradtem
Robocar consultant
This seems fine. The main thing that could go wrong is that you could plug something else in that plug -- about the only other thing people have in their homes that uses it is a large RV -- and that device might then feel free to draw 50a, in which case it will blow that breaker, but not create fire risk as all wires and gear are rated for 50a. So an inconvenience.
If someday you get a Tesla Wall connector or other EVSE that can deliver 40 amps (your car can take that) you would blow that breaker, but you would, until you replace the breaker, program that EVSE to max out at 32a.
If someday you get a Tesla Wall connector or other EVSE that can deliver 40 amps (your car can take that) you would blow that breaker, but you would, until you replace the breaker, program that EVSE to max out at 32a.
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So:
1) In almost all code situations individual wire would need to be in conduit. Plastic would be ok, but in conduit.
2) If THHN, I would have expected a 50 amp breaker on that circuit. Yes, the 80% rule applies, but you do not downrate the breaker. Ever.
3) Sure, the EVSE you have NOW will only pull 32a, but why spend the money and be limited later? Get the 50 amp installed.
1) In almost all code situations individual wire would need to be in conduit. Plastic would be ok, but in conduit.
2) If THHN, I would have expected a 50 amp breaker on that circuit. Yes, the 80% rule applies, but you do not downrate the breaker. Ever.
3) Sure, the EVSE you have NOW will only pull 32a, but why spend the money and be limited later? Get the 50 amp installed.
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