Tesla charging station

[curt swartz]

I guess what I'm asking is if it's only a recommendation then why do you have to do it? Most manufacturers recommend a lot of expensive and stupid stuff so my point is that you do not need 90 degree conductors to stay within legal code. It's simply recommended. However the copper conductor terminals only is a requirement.

The 90C is part of the listing of the equipment. It has nothing to do with the NEC ampacity of the conductors.
Its not optional unless you want to pay the manufacture to get the equipment retested with 75C wire.

 

[don_resqcapt19]

Yes, my point is that (2017) 210.19(A)(1)(a) should be deleted. 210.20(A) is sufficient, and usually it means that the requirement of 210.19(A)(1)(a) will be met. However, in a case like the OP, where it is possible to meet 210.20(A) without complying with 210.19(A)(1)(a), I don't see the point of the additional conductor upsizing required by 210.19(A)(1)(a).

Basically, what is the problem with 55A ampacity conductors for a 48A continuous load on a 60A breaker that 210.19(A)(1)(a) is trying to address?

Cheers, Wayne

Looking forward to reading your PI to fix this for the 2026 code

 

[don_resqcapt19]

The 90C is part of the listing of the equipment. It has nothing to do with the NEC ampacity of the conductors.
Its not optional unless you want to pay the manufacture to get the equipment retested with 75C wire.

I really doubt the the recomedationto use a 90°conductor is part of the listing.

 

[wwhitney]

Looking forward to reading your PI to fix this for the 2026 code

So do you agree that there's no problem with 55A ampacity conductors, a 48A continuous load, and a 60A breaker? I just want to be sure I'm not missing anything.

If so, my first thought is that 210.19(A)(1)(a) should get turned into a FPN referencing 210.20(A) and 240.4(B). Any alternative suggestions?

Cheers, Wayne

 

[jaggedben]

I really doubt the the recomedationto use a 90°conductor is part of the listing.

Maybe someone should post what the manual actually says. My recollection is that there have been other threads that described it as a requirement and not recommendation.

 

[wwhitney]

From the "Gen 3 Wall Connector Manual," page 5, first a table stating that the Wall Connector can be used on a circuit anywhere from 15A to 60A. Then the following:

•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.

That's the only hit for "90" in the manual.

Cheers, Wayne

 

[don_resqcapt19]

So do you agree that there's no problem with 55A ampacity conductors, a 48A continuous load, and a 60A breaker? I just want to be sure I'm not missing anything.

If so, my first thought is that 210.19(A)(1)(a) should get turned into a FPN referencing 210.20(A) and 240.4(B). Any alternative suggestions?

Cheers, Wayne

Not really as I don't have any data for a technical substantiation to support such a change. without such data the it is very likely the PI will be resolved (rejected) at the first draft meetings.

 

[wwhitney]

Not really as I don't have any data for a technical substantiation to support such a change. without such data the it is very likely the PI will be resolved (rejected) at the first draft meetings.

Yeah, all of my PIs are based on logic, which apparently the CMPs find insufficient. The basic argument:

A 55A ampacity wire is sufficient for a 48A continuous load, per the definition of ampacity and per the exception to 210.19(A) that allows it with a 100% rated breaker.

A 60A breaker is sufficient for protecting a wire with 55A ampacity per 240.4(B).

A 60A breaker is sufficient for a 48A continuous load, per 210.20(A).

So everything is protected according to its ampacity, and the breaker is sufficiently sized to avoid nuisance tripping from the continuous load.

Cheers, Wayne

 

[don_resqcapt19]

Yeah, all of my PIs are based on logic, which apparently the CMPs find insufficient. The basic argument:

A 55A ampacity wire is sufficient for a 48A continuous load, per the definition of ampacity and per the exception to 210.19(A) that allows it with a 100% rated breaker.

A 60A breaker is sufficient for protecting a wire with 55A ampacity per 240.4(B).

A 60A breaker is sufficient for a 48A continuous load, per 210.20(A).

So everything is protected according to its ampacity, and the breaker is sufficiently sized to avoid nuisance tripping from the continuous load.

Cheers, Wayne

Exactly...logic is not a part of the code change process.

 

[JEFF MILLAR]

Must use the 60 Deg. C. ampacity column and if this is a continuous rated load ( 3 hours or more ) and yes best modern copper conductors dual rated 75 / 90 c. But rated amps must follow the 100 amp load and code terminal ratings. Correct ?

 

[Strombea]

The 90C is part of the listing of the equipment. It has nothing to do with the NEC ampacity of the conductors.
Its not optional unless you want to pay the manufacture to get the equipment retested with 75C wire.

If the 90 degree is a part of the listing then why does the OP specify "Tesla recommends" ( even though now we have concluded that romex 6awg wouldn't work anyway because it happens to be continuous) I just want to make sure we all understand the difference between recommendations and requirements

 

[Strombea]

Must use the 60 Deg. C. ampacity column and if this is a continuous rated load ( 3 hours or more ) and yes best modern copper conductors dual rated 75 / 90 c. But rated amps must follow the 100 amp load and code terminal ratings. Correct ?

The only other side of this discussion is the use of the chargers that have the 50 amp cord end, but it is the same charger pulling the same amperage continuously. In these cases obviously all of us have pre-wired in garages an RV outlet with 6-3 Romex and when the house is purchased many people have use these for the car chargers because the car charging companies are coming out with that configuration and there's nothing anybody can do to stop customers from plugging into it. Soooo now what? We label all 50 amp RV plugs that were wires with romex "not for use with car chargers"???

just use 6-3 romex and assume it was pre wired as an RV plug.

 

[jaggedben]

If the 90 degree is a part of the listing then why does the OP specify "Tesla recommends" ( even though now we have concluded that romex 6awg wouldn't work anyway because it happens to be continuous) I just want to make sure we all understand the difference between recommendations and requirements

Well apparently the OP needs to learn that significance because he mistated what the manual says, as Wayne quoted it in post #26.

 

[curt swartz]

The only other side of this discussion is the use of the chargers that have the 50 amp cord end, but it is the same charger pulling the same amperage continuously. In these cases obviously all of us have pre-wired in garages an RV outlet with 6-3 Romex and when the house is purchased many people have use these for the car chargers because the car charging companies are coming out with that configuration and there's nothing anybody can do to stop customers from plugging into it. Soooo now what? We label all 50 amp RV plugs that were wires with romex "not for use with car chargers"???

just use 6-3 romex and assume it was pre wired as an RV plug.

The Tesla charge cords that have 50 amp adapter plugs are limited to 32 amp. They are designed to be connected to a 50 amp receptacle that is part of a 40 or 50 amp circuit. Tesla does make a cord that has a factory installed 50 amp plug (no adapter options) that must be part of a 50 amp circuit and provides a 40 amp charge rate.

All manufactures of charge cords equipped with a 50 amp plugs will have a maximum charge rate of 40 amps but most are limited to 32 amps. There is no issue connecting them to a 50 amp receptacle supplied by 6/3 NMB.

If a Tesla Wall Charger is going to be installed it must be hard wired. The charge rate must be set to match the wire and overcurrent device installed.

 

[sunbear]

I am getting quotes from electricians to install a tesla gen3 charger in my garage.

From reading this thread, would it be fair to conclude that using 6 awg 3-conductor romex wire would not meet code due to Section 210.19(A)(1) which states
"Where a branch circuit supplies continuous loads or any combination of continuous and noncontinuous loads, the minimum branch-circuit conductor size shall have an allowable ampacity not less than the noncontinuous load plus 125% of the continuous load."

125% * 48A = 60A

Table NEC table 310.15 (B) (16) shows that #6 Romex is only rated for 55A (in the 60C column) therefore #6 romex would not be code compliant for a Tesla charger installation?

Thanks.

 

[Dennis Alwon]

I am getting quotes from electricians to install a tesla gen3 charger in my garage.

From reading this thread, would it be fair to conclude that using 6 awg 3-conductor romex wire would not meet code due to Section 210.19(A)(1) which states
"Where a branch circuit supplies continuous loads or any combination of continuous and noncontinuous loads, the minimum branch-circuit conductor size shall have an allowable ampacity not less than the noncontinuous load plus 125% of the continuous load."

125% * 48A = 60A

Table NEC table 310.15 (B) (16) shows that #6 Romex is only rated for 55A (in the 60C column) therefore #6 romex would not be code compliant for a Tesla charger installation?

Thanks.

IMO, that is correct however you can use #6 Seu cable which is good for 75C

 

[falconewk]

I'm pretty sure the last Tesla charger we installed was two wire with ground, no neutral required. I also use SEU (6-2 with ground). CerroWire shows their cable is rated for 90C.

 

[Dennis Alwon]

I'm pretty sure the last Tesla charger we installed was two wire with ground, no neutral required. I also use SEU (6-2 with ground). CerroWire shows their cable is rated for 90C.

The cable is rated 90C but in general you can only use it at 75C or less.

 

[falconewk]

Yes, because of the terminations on either end right? I only mentioned the 90C because I thought it was a requirement in the OP that the manufacturer wanted 90C rated conductors.

 

[Dennis Alwon]

Yes, because of the terminations on either end right? I only mentioned the 90C because I thought it was a requirement in the OP that the manufacturer wanted 90C rated conductors.

Almost all standard cables are 90C.. even nm cable is rated 90C we just can't use it over the 60C rating