Wall Charger Installation Help

[leverd]

Hi Folks,
My Rivian wall charger is being replaced because I have been plagued with the "charging slowed issue" and RIvian provided the following instructions. My local installer who recently replaced my panel (400A) is providing (I think) conflicting installation information. The wire to the wall charger is 6AWG NM-B.

Please help me sort through what needs to be done.

Rivian says:
You'll want to be to be within the 90 degree column. Per NEC (210.19 (A)(1), conductors for fixed-in-place appliances that are expected to run at a maximum current for 3 hours or more, must be sized at least 125% of the appliance’s maximum load. For a 48-amp EV charger like the Rivian Wall Charger, the conductor needs to be able to handle at least 60 amps continuously. If you're within the 75 degree this will not cover the 125% if you're using a 60amp breaker, if this is what you're doing I would recommend charging at no more than 40 amps during your sessions.

My local installer says
On the chart, we need to go by the 75* column since the lugs on the circuit breaker are rated at 75*. (This is standard across all circuit breaker brands). According to this chart, at 75*, #6 Copper with THHN-THW insulation will deliver up to 65A continuous load. In summary, from the NEC table, #6 is the correct size wire.

What’s the right thing to do given that I am not inclined to replace/upgrade my new panel.

Please help. Thanks!

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[SANZC02]

Hi Folks,
My Rivian wall charger is being replaced because I have been plagued with the "charging slowed issue" and RIvian provided the following instructions. My local installer who recently replaced my panel (400A) is providing (I think) conflicting installation information. The wire to the wall charger is 6AWG NM-B.

Please help me sort through what needs to be done.

Rivian says:
You'll want to be to be within the 90 degree column. Per NEC (210.19 (A)(1), conductors for fixed-in-place appliances that are expected to run at a maximum current for 3 hours or more, must be sized at least 125% of the appliance’s maximum load. For a 48-amp EV charger like the Rivian Wall Charger, the conductor needs to be able to handle at least 60 amps continuously. If you're within the 75 degree this will not cover the 125% if you're using a 60amp breaker, if this is what you're doing I would recommend charging at no more than 40 amps during your sessions.

My local installer says
On the chart, we need to go by the 75* column since the lugs on the circuit breaker are rated at 75*. (This is standard across all circuit breaker brands). According to this chart, at 75*, #6 Copper with THHN-THW insulation will deliver up to 65A continuous load. In summary, from the NEC table, #6 is the correct size wire.

What’s the right thing to do given that I am not inclined to replace/upgrade my new panel.

Please help. Thanks!

I would listen to your electrician, 6awg at 75c will go to 65 amps, with a 60 amp breaker you should be good at 48 amps.

 

[Electrified Outdoors]

NM-B while it has 90C insulation is locked to the 60C ampacity.

So max ampacity is 55 amps for #6 NM-B. Technically if your running 48 amps continuous, you need either #4 NM-B (fairly difficult to source) or you need #6 THHN in conduit.

Many electricians will still use #6 NM-B though.

I would suggest leaving what you have and setting max charge rate to 40 amps instead of 48.

 

[Revelation]

Yep. 6awg Romex would be fine for 60A if it were not continuous for 3+ hours. Code states that you have to use the 80% rule when running loads continuous for 3+ hours.

For EV charging you have to factor in the 80%. Thus you need at a minimum 6awg THHN/THWN in conduit for 60A thus running at 48A on your load as 48A is 80% of the 60A breaker / wire rating.

 

[Zoidz]

As others have said, 6AWG THHN or TWH is fine. The Rivian statement is half correct, half wrong. You need a 60 amp circuit to to meet the 125% requirement, but then the Rivian comment seems to be saying that the conductor needs to be rated 125% above the breaker rating which is incorrect. Your equipment is rated at 48 amp, 125% is 60 amp.

With all that said, you still should consider charging at 40 amp instead of 48 amp, unless you really need the slightly faster charge time. 40 amps will be a bit more efficient due to less heat loss and a little less heat wear and tear possibilities on the installation. It will also reduce the possibility of temperature throttling that seems to be popping up fairly often these days.

NEC 625.41:Overcurrent protection
"... shall be sized for continuous duty and shall have a current rating of not less than 125% of the maximum load of the equipment."

Rivian:
"For a 48-amp EV charger like the Rivian Wall Charger, the conductor needs to be able to handle at least 60 amps continuously. If you're within the 75 degree this will not cover the 125% if you're using a 60amp breaker,..."

 

[R1Thor]

To summarize others' and my experience with Rivian and their requirements for compliance:

6 AWG THHN (I used SimPull from Lowes), 90 deg NEC rated conduit, 60A Breaker

I just went through this replacement myself with Rivian and sent them these images, which they validated were within compliance (I wanted to make sure there was NO question if ever there was a need for another warranty claim). They did CYA themselves and state the requirements for using a certified electrician (I have one in the family and work with several Electrical Engineers who also validated my install). Rivian did recommend (but not require) I use metal conduit, but where my conduit is routed, I do not see a need as there's approximately <0.1% chance of this seeing any kind of impact or incidental damage.

 

[SwampNut]

When I had a failed EVSE, Rivian offered to send an electrician at their own cost to replace it. I did it myself (and installed it) but they offered it without being asked.


EDIT: Found the email.

Replacement Installation

To maintain warranty coverage, your replacement Wall Charger must be installed by a licensed electrician. If you're interested, we can arrange for an electrician from our installation partner, Qmerit, to replace the faulty unit and install the new unit, at no cost to you.

 

[R1Thor]

When I had a failed EVSE, Rivian offered to send an electrician at their own cost to replace it. I did it myself (and installed it) but they offered it without being asked.


EDIT: Found the email.

Replacement Installation

To maintain warranty coverage, your replacement Wall Charger must be installed by a licensed electrician. If you're interested, we can arrange for an electrician from our installation partner, Qmerit, to replace the faulty unit and install the new unit, at no cost to you.

Dang, how long ago was yours replaced?

This was the verbiage I received:
" Please note that, in order to maintain warranty coverage on the replacement, the Wall Charger must be installed by a licensed electrician, in accordance with the provision of national electrical codes and standards as well as the Installation Guide. We recommend 8AWG THHN in a metal (non-flexible) current hardwired to a dedicated 60 amp breaker. "

I had to question them on the 8AWG THHN, too, and they qualified that with " Wire gauge is dependent on circuit breaker amperage. for a typical 60amp, we suggest 6AWG. For 50amp - 8AWG, 40amp - 8AWG, etc. If you are going to use a smaller breaker circuit than that, I can give you the specifics on that if needed."

Seems like there isn't a standard script, and it also (now seemingly) appears we don't all get the same level of service. Not complaining, just...pointing that out.

 

[SwampNut]

That email was on 6/28/24. They did have much more about using a licensed electrician but didn't say anything at all about the wiring. But my failure was a clear hardware problem, and yours was kind of mysterious. I probably could have used #8 but didn't bother with considering it at all since my run was only a few feet and overbuilding it would not be costly.

 

[leverd]

Thanks everyone. This is helpful, but I am still somewhat confused on how to proceed. So I contacted my local electrical co again to get clarification. I am not necessarily doubting the recommendation, just looking for confirmation (I have no expertise here), as Rivian emphasizes the 90* column not the 75*.

Here's what I asked:
"NM-B conduit, though acceptable, is not ideal for the Rivian use case? That is, if I want to be able to use the full 48 amps charging capacity then I would need the THHN conduit. For safety and performance do you recommend redoing new conduit at 6AWG THWN as the table indicates?"

His response:
"The THHN and THWN are both PVC-based insulations having a nylon sheath. Both are listed at being able to handle up to 75 Amps at 90 degrees according to table 310.16 (that you provided). Each type of insulation is designed for a different environment. THHN is geared towards a high-heat dry environment, such as the interior of your house. THWN is designed for use in a high-heat, high moisture environment, such as an industrial building where there is water present, or perhaps in conduit near and around a swimming pool. The wire installed for your wall connector is 6/3 Romex, which uses THHN. Inside your house, it is more than adequate to handle the full output of your wall connector for an extended period of time.


Thanks again for your help. Likely, as recommended above I'll leave the NM-B wiring as is and set the charger to 40amps.

 

[dradam]

Yes. Nm-b 6AWG is derated to the 60c column because of the close proximity of wires and heat concerns. At 40A you will be within the correct rating.

FWIW I am set up with xhhw-2 in flexible metal conduct on a 60 A breaker . While this could allow 48 A charging I have only ever charged at 30A I charge at night when the rates are lower. While it may be taking more hours to charge… makes no difference if I’m asleep.

Best

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