Wire Guage clarification help.

[DuoRivians]

If you’re using the Rivian wall charger, the pre-cut out holes accommodate either 0.5” or 1” conduits. Just to keep in mind

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[Zoidz]

Thanks to all.
So if I don't use 4AWG romex because it is too hard to handle and use 6AWG THHN in conduit (6/3 and a ground for future proofing) instead, (which is OK for a 60 A Breaker) , Can I use a flex conduit ? If so I think 1 inch would be OK. My electrician was against conduit and THHN-- said it would be hotter? Is he mistaken?

TIA

IMO the electrician is wrong about the THHN running hotter for this simple installation. If it was a 4" conduit with 20 conductors running at full current, yes it will run hotter. But for this install with 3 conductors and proper size of conduit, it will have plenty of air space on each of the three conductors to dissipate heat (unlike one conductor buried in the middle of 19 others) plus the thermal conductivity of the conduit.

 

[electruck]

Easy answer, find another electrician. (Good) Licensed electricians follow code, they don't make up their own.

 

[dradam]

Thanks to all of you !!

I am leaning towards this tray cable from the link below.

https://www.wireandcableyourway.com/6-3c-thhn-pvc-tray-cable-with-ground

Size: 6 AWG
Number of Conductors: 3
Conductor Strand: 7/.0612
Ground Wire Size: 8 AWG
Minimum AVG Insulation Thickness: 0.91 mm / 0.036 inches
Minimum AVG Jacket Thickness: 1.52 mm / 0.060 inches
Outside Diameter: 17.53 mm / 0.690 inches
Copper Weight: 0.300 lbs per ft
Net Weight: 0.434 lbs per ft
Allowable Ampacity: 75 Amps
Rated at 90°C dry, 75°C wet.

At this spec it seems to exceed heat/ampacity ratings necessary for my 48 V EVSE on a 60 amp breaker.

I am adding one conductor in case I need a neutral in the future. Hoping you all will chime in with a thumbs up (or down ) if my thinking is incorrect.

Many thanks again.

 

[sub]

If your electrician needs you to ask random internet strangers what is required to satisfy code, they need to go back to electrician school.

I do think however that debate over appropriately sized romex vs appropriately sized THHN in conduit is a good one.

Heavy romex may be ungainly, but running conduit behind the drywall is pretty damn hard too.

The odds of getting conduit run without major drywall work afterwords is likely pretty low. And if you are ripping out all of the drywall, then running Romex would probably be pretty easy at that point too.

If your garage is unfinished and you already have exposed pipes all over the place, then yes, conduit is certainly the easiest option. But if you have a finished garage and don't want to add ugly conduit pipes hanging from the wall, I think romex would be much easier.

Or, perhaps I am just unusually bad at getting conduit into the wall without cutting huge holes.

 

[dradam]

Thank you sub,

I can do anything I want because the panel is in an unfinished area and I have a straight shot to a column I built in the middle of the garage that will hold the charger. I am just trying to find the safest wiring option that makes sense. Please check the pereceeding post ans shre your opinion. At the least I hope this thread helps others like me trying to sort conflicting information.

TIA.

 

[R1TCntrlMaIzzy]

Like a few have mentioned, you might be wise to seek feedback from other licensed electricians in your area. Plus you are doing a lot of research that person should have, IMO.

I just had, two days ago to be exact, my Riv WC, with Romex 6/3 and a 50 amp breaker installed. Our electrician friend had the 60 ft I needed, left over from another job, so we used it. The only downside is a 18-20 mile per hr charging rate, but it works for me.

 

[electruck]

I do think however that debate over appropriately sized romex vs appropriately sized THHN in conduit is a good one.

There really is no debate. You can't properly connect 4 AWG Romex to the EVSE, it is designed for a max of 6 AWG. If you run 4 AWG Romex from the breaker, you will have to run that into another box and then run 6 AWG THHN from there to the EVSE. Not worth it, the fewer connections the better. This is why electrical codes exist, to force decisions based on safety and not on convenience.

 

[Zoidz]

Thanks to all of you !!

I am leaning towards this tray cable from the link below.

https://www.wireandcableyourway.com/6-3c-thhn-pvc-tray-cable-with-ground

Size: 6 AWG
Number of Conductors: 3
Conductor Strand: 7/.0612
Ground Wire Size: 8 AWG
Minimum AVG Insulation Thickness: 0.91 mm / 0.036 inches
Minimum AVG Jacket Thickness: 1.52 mm / 0.060 inches
Outside Diameter: 17.53 mm / 0.690 inches
Copper Weight: 0.300 lbs per ft
Net Weight: 0.434 lbs per ft
Allowable Ampacity: 75 Amps
Rated at 90°C dry, 75°C wet.

At this spec it seems to exceed heat/ampacity ratings necessary for my 48 V EVSE on a 60 amp breaker.

I am adding one conductor in case I need a neutral in the future. Hoping you all will chime in with a thumbs up (or down ) if my thinking is incorrect.

Many thanks again.

I assume you want to use this cable assembly to avoid installing conduit?

Per NEC, the cable you are looking at (TC-ER) cannot be installed exposed or unsupported . It requires some sort of supporting cable tray or raceway. See 336.10 below.

However, per 336.10(9) if you use TC-ER-JP which includes an additional low voltage wire pair, you CAN use it residential exposed, install just like NM (Romex) as per the reference to Article 334 Part II.

Yes, I know it makes little sense, but the code is the code and if you are getting inspected, a competent inspector will fail TC-ER exposed in a home.

The reason they allow the exception in 10(9) is for TC-ER-JP is that generator installers use it, and HVAC installers use that type of cable for mini-split residential installations, where the power is fed to the equipment on the larger gauge wires, with the control signal on the low voltage pair.

 

[invernite]

Remember team the NEC is the minimum standard for safety to prevent fires

So regardless of what you have the vehicle set for for amperage the electrical supply system must meet NEC standards or better. Also when you install systems you may have a plan to use substandard wiring knowing you will back down the charging current of the vehicle to be safe but the installed system must be 100% usable for the next guy who may and should be able per the installed breaker and wiring max out the vehicle charging current since he/she will assume the install was per code

This is a great point!

 

[dradam]

Gil,

Thank you for you detailed response. My primary concern is safety. Odd that an added control wire changes the code for that tray cable.

Thanks to all who have responded. It appears to me that 6AWG in Flexible metal conduit meets code and has 75 ampacity. I think that is where I am headed--

TIA again.

 

[diehlryan]

The wall charger install guide from Rivian indicates 6AWG on 60AMP breaker. Page 17.

https://assets.rivian.com/2md5qhoea...wall-charger-install-guide-en-us-20230525.pdf

 

[jeeden]

If you don't want to use metal conduit you could do like I did and use liquid tight conduit. You can usually buy kits that have 40 ft in them and come over the connectors. I have an Autel charger and it too has a maximum size of 6 AWG so I wound up using THHN as well. Either way conduit is the way to go if you have open walls and a screenshot. If you're going to a center column I would put a double size piece of conduit in and pull 8 conductors so you already for your second charger to go right next to the first although that is a considerable increase and expense since wire is so expensive right now.

I think the electrician in this case is not recognizing the continuous load.

My father-in-law's an electrician and wound up taking his annual refresher right after I had installed my charger. (Did it myself) He pointed out how in previous years there was some language about EV chargers but this year and there was a lot and nearly the entire new portions of the code were about EV charger installs. Since it's relatively new code and technology I think you're going to have a lot of electricians that either do know what they are talking about or do not.

 

[dradam]

Thank You Jeeden, I have considered a 40 ft run of Liquid tight conduit and may still go that way. Although I have had trouble finding information on heat and its affect in liquid tight or even hard PVC conduit. I focused on the Flexible metal only because I can by it with all the connectors in it.

The Idea of future sizing the conduit is great, but My Sub panel could not support another breaker. If we one day go with two EV's I may switch to a single load shaing charger with Two cables such as the Grizzl-E.

Many thanks for chiming in.

 

[dradam]

The wall charger install guide from Rivian indicates 6AWG on 60AMP breaker. Page 17.

https://assets.rivian.com/2md5qhoea...wall-charger-install-guide-en-us-20230525.pdf

Thank you for replying.

We are Neighbors, I live just behind the village. I will keep and eye out for your vehicles.

Yes, I know the manual specifies 6AWG, many are using 6/2 AWG romex, but that has a maximum of 55Ampacity. While it should be fine, my understanding is that it does not meet code.

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