Electrical people. Opinions on this L2 Install?

[teartags]

I just moved into a new house. My previous house had a shed where I ran #6 THHN in conduit from the panel to the charger and charged at 48 amps on a 60 amp breaker. It was easy because it was all exterior conduit runs.
This house is considerably more difficult, because the panel is on the opposite side of the garage through a finished basement, so I called my electrician. He's saying conduit will likely be impossible and wants to run 6-3 Romex to a shutoff in the garage. It'll be exterior conduit from there and hardwired to the charger. I'll be doing that last bit, so I can locate the charger where I want when I figure that out (I'm converting the space back to a garage and it's currently full of boxes from moving). He's telling me he can put a 60 amp breaker on it, but after researching here, it sound like I need to keep it at 50 and charge at 40? My Autel charger doesn't have a setting between 40-48 amps. Though, it's going through cool basement walls/ ceiling in CO, so heat should not be a large issue. I read a thread that said 48 amps might be OK if that's the case?
I guess I'd go to #6 THHN from the shutoff to the charger? Or #8 if only charging at 40 amps. I also plan on torqueing the snot out of those connections!
Thanks for the read and any advice.

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[NY_Rob]

Copper #6 NM-B (Romex) is only rated for 55 amps non-continuous load, de-rate that by 20% for continuous loads, and you're now at 44 amps, so set your EVSE at 40amps and sleep well at night. For the small price diff between #6 and #8 THHN from the shutoff to the EVSE run, I'd keep it all #6 for safety... installing a 50 amp breaker on 55amp rated #8 THNN is cutting it kind of close if something shorts out that #8.

 

[Riviot]

He's telling me he can put a 60 amp breaker on it,

So you're saying a sub panel? How long of a run would it be directly? #6 THHN is rated to 75 amp so you're good with 60amp breaker.

Stick with #6 for the whole project, you'll sleep better.

https://www.cerrowire.com/products/resources/tables-calculators/ampacity-charts/

also plan on torqueing the snot out of those connections!

Torque to spec, over torque will fail as much as under torque.

 

[SANZC02]

They could run 4/3 Copper Romex to the cutoff box, that gives you 70 Amps, then you could use the 60 Amp breaker and Run #6/THHN for the charger to get your 48 amp charging.

 

[HaveBlue]

Separately I charge at 40A on a Maxicharger and the Max pack has no trouble getting to wherever I need it overnight. My panel won't accommodate a 60A breaker.

6/3 Romex is only rated for 40A of charging. If he puts it on a 60A, it's on him. You only need 6/2. It's a long run. He'd be better off using 6-6-6 SEU which is also HH rated to get you to 48A on the maxicharger. #8 romex on a 40A breaker is only good for 32A continuous. #4 SEU is an option I guess but overkill.

 

[Eeyore]

Torque to spec, over torque will fail as much as under torque.

Word. If you're worried about connections getting loose, turn off the breaker and hand tighten the connections after a few charging cycles.

 

[Roads76]

He's telling you wrong, like so many others I've seen. As was already mentioned you should only run the romex to 44 amps. If you're not sweating the extra amps just charge at 40 amps and be happy. I used 6/2 MC cable, not near as flexible as romex, but it was easy enough, once I hit my garage I stripped the mc and finished the run in emt because it looks better. The 6/2 MC uses #6 THHN wire.

 

[Zoidz]

Let's separate the EV derating from the base electrical install. He's correct and code compliant with the 60 Amp breaker. NEC allows you to round up to the nearest size breaker if a breaker is not available at the rated current. So in this case, you can round #6 Romex 55 amp ampacity rating to a 60 amp breaker. It's legal and perfectly safe - there is buffer built into wire size heat calculations that drive the NEC breaker requirements.

The 80% rule applies to the CIRCUIT not the breaker. So it's 80% of the Romex 55 amp ampacity, or 44 amps max charging current at the EVSE.

You could install #6 Romex to reduce voltage drop and heating. But as mentioned above, why didn't the electrician suggest 6/2 or 6/3 (future proof) MC with #6 THHN conductors? Installation ease is nearly the same as Romex (bend radius is larger than Romex) and more versatile than conduit.

Edit - addition: The difference between 40 amp and 44 amp charge rate is about 10%. My OpenEVSE installation allows me to run at 40 or 44 amp, but I have it set for 40 instead of 44. The difference is only 10% and since I charge overnight, the extra 30 to 90 minutes is irrelevant, and it is slightly more energy efficient to charge at a lower rate due to lower heat losses. Do you really NEED to charge above 40 amps?

 

[ElGuano]

why didn't the electrician suggest 6/2 or 6/3 (future proof) MC with #6 THHN conductors? Installation ease is nearly the same as Romex (bend radius is larger than Romex) and more versatile than conduit.

Is MC as easy to install? I understood Romex is typically used internally when it needs to be fished between walls. If there's a significant run, feels like it would be a lot tougher to do that with MC.

If you can run externally, conduit is pretty darned convenient.

Edit - addition: The difference between 40 amp and 44 amp charge rate is about 10%. My OpenEVSE installation allows me to run at 40 or 44 amp, but I have it set for 40 instead of 44. The difference is only 10% and since I charge overnight, the extra 30 to 90 minutes is irrelevant, and it is slightly more energy efficient to charge at a lower rate due to lower heat losses. Do you really NEED to charge above 40 amps?

I think this is a point that is often overlooked. It's easy to get caught up in the "can I support a full 60A breaker and max it out?" In reality, even 24A/240 is a huge improvement over trying to charge with 120v, it's ~4x faster. So you go from charging at 2mph to 8mph, and overnight you're probably adding >100mi of range. Over 24 hours you go from 0 to 100% on a max pack. Putting in a 50amp breaker versus 60amp isn't going to be a big deal for 99% of people.

 

[Zoidz]

Is MC as easy to install? I understood Romex is typically used internally when it needs to be fished between walls. If there's a significant run, feels like it would be a lot tougher to do that with MC.

That's why I said nearly as easy except for bend radius. If you are running inside a wall and need to make sharp bends, MC might not work. If you are running in a basement, attic or crawl space, etc. and need to snake around ductwork, pipes, building supports, beams, etc. then MC is just as easy as Romex, where conduit would be a pain.

 

[orttauq]

On this subject I have a question. I have some extra 6-3 NMWG that I planned to use for a short run. I am lucky that were I want to install my Rivian brand charger is less then 10 feet (like 8ft of wire) from my primary panel. Can I use the 6-3 NMWG? It is open space in my basement to then punch through an outside wall near my back door. Thanks for input.

 

[ElGuano]

On this subject I have a question. I have some extra 6-3 NMWG that I planned to use for a short run. I am lucky that were I want to install my Rivian brand charger is less then 10 feet (like 8ft of wire) from my primary panel. Can I use the 6-3 NMWG? It is open space in my basement to then punch through an outside wall near my back door. Thanks for input.

My understanding is that you cannot run NMB in the open (as in, exposed along a wall). It can be in the wall, or in conduit if on the outside wall, but that conduit if it holds NMB can't be in an wet/damp location. I'm not sure how garages factor into wet/damp. So I realized this reply is probably not helpful at all

 

[teartags]

Thanks everybody.
Wire needs to be snaked through multiple walls and ceilings and I'm trying to cut as few holes in the sheetrock as possible. so will probably stick with the Romex. I'll suggest 6-2 over 6-3 because I'm guessing it smaller and tighter bending.
40 amps is fine. I just figured why not get 48A if it's easy.

 

[orttauq]

My understanding is that you cannot run NMB in the open (as in, exposed along a wall). It can be in the wall, or in conduit if on the outside wall, but that conduit if it holds NMB can't be in an wet/damp location. I'm not sure how garages factor into wet/damp. So I realized this reply is probably not helpful at all

Thanks, This is helpful as I did not know about it being not allowed for exposed installs. It is a short run and all in the basement floor joists.

 

[babock]

Thanks everybody.
Wire needs to be snaked through multiple walls and ceilings and I'm trying to cut as few holes in the sheetrock as possible. so will probably stick with the Romex. I'll suggest 6-2 over 6-3 because I'm guessing it smaller and tighter bending.
40 amps is fine. I just figured why not get 48A if it's easy.

Not sure why some people were recommending 6/3. You only need the two hots. No neutral is needed.

My electrician ran 6/2 70 feet with a 60A breaker to a hard wired charger that will be charging at 48A.

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