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Charge Amperage Dropping in the middle of the charge, 32 --> 16 Amp
- Thread starter gotoma8
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ATPMSD
Active Member
Disagree. They should know, and be able to explain, the difference between the $12 outlet and the $80 outlet. They are supposed to be the expert.!
The installer of equipment might not know the difference. An Electrician should know the difference.
I ran the Leviton outlet for 2 years at work and removed it every day, sometimes twice per day when I left for lunch. This was using a Gen 1 UMC with 40A draw. One day it just stopped working due to an internal short.
They will say that "both are rated for 50A circuits, which means that both are suitable for up to 40A continuous use".
Then it is time to either specify/buy the outlet yourself as an informed customer or to find an electrician who knows the difference.
In the end though it's like anything that costs 20% of the alternative part. It is likely to be made of the absolute cheapest materials and will break in a year or two of continuous use. Buyer beware!
If you were faced with the choice of tires and on one hand is the $300 per tire option, and the other is the $60 option. You ask the tire guy "What is the difference?" and he replies " Both are rated for your car which means they are suitable for driving."
Some tire guys may only sell $60 tires, and probably don't put those on your Tesla either.
They definitely needs to be some universal training via certification or code enforcement on EV’s, both to keep people safe and to make it easier for electricians. I’m mad at my installer, but he may have thought he was doing what is absolutely right because it all met code — which the savvy of us know is the bare minimum to avoid electrical catastrophe.
Whoa, no, that is not correct at all. There aren't different rating requirements because of something being used for an EV. There is one rating requirement, which has two parts: full rating for intermittent use or 80% usage for continuous use. And it is totally clear that 6 gauge Romex is not EVER allowed for a 60A rated circuit. Period.
davewill
Active Member
Actually the electrical code is fairly conservative as far as safety goes. It think the real question is why a UL-listed part from a major brand is such a low-quality POC.
Makes you wonder how it got past UL, since UL has an obvious interest in ensuring that things have enough margin of safety in intended use so that they do not cause insurance losses (e.g. fires in buildings). Indeed, checking things for electrical and fire safety was one of its earliest focuses.
ATPMSD
Active Member
In the code, since there is not a 55-amp breaker to match 55-amp wire you can use a 60-amp breaker. NEC 240.4 (B) I believe.
With EVs there is the additional issue of the 80% rule which is why #6 romex cannot be used.
No! Damn it. That round up provision is useless and not applicable here. You've been around here so actively for so long, I thought you would have seen this covered in the many previous threads on it. You're making this same mistake people frequently make. You are thinking that the act of rounding up the breaker automagically makes ALL of the other parts of the circuit fully rated to be an official usable 60A circuit. It doesn't! Lowest rating limitation still has to be the limit for the whole thing. The cable is 55A rated, so the circuit can't be any higher than 55A rated.
That's not really why; it's not EV specific. People are trying to set up a device designed to pull 48A continuous current. Code says a 48A continuous load must have a circuit rated to 125% of that continuous current. That is 60A. 55A rated cable does not meet that requirement.
[EDIT] Excuse me? I withheld putting a disagree marker on you because of your generally good and helpful reputation here, but just corrected your misinformation. And then you mark this with a disagree for the correct information?
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Hmm. I did just go back and reread it to check for the context, and here is what I see. You did not say it is a mistake:
There it is. You said it is allowed by code. It is not. You said it is fine for welders, saws, etc. It is not.
Those statements are just false. What context am I missing?
So am I thinking correctly then that 6/3 Romex Al at 75 degrees is appropriate for a 50 amp circuit to power a gen 2 MC? It draws 32 amps, but my previous 6-50 Leviton surface mount outlet is overheating and down clocking to 16 amps. I’m looking to upgrade to a 14-50 Eaton flush mount. (The Eaton is the new cooper that Tesla originally recommended: Cooper 5754N). For context, I changed my amperage in my car to 28 amps and it ran fine from 30% to 85% on a 80 degree day.
davewill
Active Member
Yes, 6/3 romex is good for a 50a circuit. It can feed a mobile connector for 32a charging, or a wall connector for 40a charging.
Thanks! I thought so, but not being an electrician I always doubt myself. New 14-50 adaptor for the mobile connector is on the way, and I’m ordering the Eaton version of the Cooper 5754 as we speak.
ATPMSD
Active Member
The full sentence is
- Using #6 Romex for a 60-amp circuit, while allowed by code, is again fine for welders, saws, etc. but it does not meet the requirements when used for charging EVs
"conductors (other than flexible cords, flexible cables and fixture wires) shall be protected against overcurrent in accordance with their ampacities specified in 310.15, unless otherwise permitted or required in 240.4(A) through (G)."
"This section is often referred to as the round-up rule. In accordance with 240.4(B), the next higher standard overcurrent device rating (above the ampacity of the conductors being protected) shall be permitted to be used, provided all of the conditions in 240.4(B)(1) through (3) are met"
Since I am not an electrician so I am willing to admit I could be wrong. But at this point if continue to disagree please sight a source.
Well, no, it cannot be correct. A circuit either is or isn't a proper 60A circuit. That can't depend on what appliance you are using on it. If a saw needs a 60A circuit, that isn't one. The different appliances you use on it are about whether you get to use the full amp rating for intermittent use or only get to use 80% of it continuously.
Applies...to what? The round up rule is only about what circuit breaker you are allowed to attach. It does not speak to how much current you are allowed to run on the conductors.
Those are details and conditions about when you would be allowed to round up the circuit breaker. And those are correct. I have no problem with that. On that end of it, you would physically be allowed to put a 60A breaker on it, because 55A isn't a standard size. But then how would you be allowed to rate and use the circuit? Ah! That's where the problem lies. 55A is still the limit of the conductor, and there is no provision that allows you to round up or overload the usage above the rating of the conductor. So you can only use up to 55A intermittently or 44A continuously on 6 gauge Romex. That is how that works.
I found a fantastic video that explains the details of how and when the round up rule can be applied. One of the examples he uses is #2 copper at 75 deg C, rated for 115A. That is a non standard size, so the breaker can use a 125A. But he emphasizes multiple times that the conductor's rating is still only 115A, not 125A. So you still cannot use it for more than 115A rated loads.
So I have been over this round up thing on #6 Romex a few times before, and the result still is that the round up rule does exist, but it doesn't apply in the way people think it does, where the whole thing BECOMES a 60A circuit. The configuration that could properly use it, would be with the #6 Romex, at a 55A limit, 60A breaker, but then you have to have some piece of equipment that would still honor the 55A maximum rating. I have heard of only one EVSE that does have a setting to run at 44A continuous. That times 125% would be a 55A rating, and it could be used in that way. But you can't use 48A continuous.
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ATPMSD
Active Member
And I'm sorry if I sounded frustrated. I just don't like seeing people recommend using the round up breaker rule because it almost always leads people to misunderstand it and use it wrong, so I would rather people just not mention it, since it's so rare for anyone to be able to use it appropriately.
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