Electrical wiring for charger

[docwhiz]

I didn’t realize you could still buy a house with aluminum wiring.

Those are weird options IMO. Agreed on the question about what gauge wiring.

We did 60amp / 6 ga / copper direct hardwire. Suggest doing two of them when building, way easier than after the fact.

I had the electrician install two charge circuits in my new garage. 6gauge copper. Only added a few hundred dollars.

Sponsored

 

[nc10]

Rare today, maybe less rare tomorrow. Always a good idea to anticipate future needs.

Could make a case as a bad idea, in the spirit of minimizing GHG emissions. Making a case for only installing stuff to meet foreseeable reasonable needs and also minimizing the peak loads on power generation, As It's the peak loads that are often met with fossil fuel power.

But each case is different. Just need to think this kind of stuff through more in the future.

 

[MIG]

Could make a case as a bad idea, in the spirit of minimizing GHG emissions. Making a case for only installing stuff to meet foreseeable reasonable needs and also minimizing the peak loads on power generation, As It's the peak loads that are often met with fossil fuel power.

But each case is different. Just need to think this kind of stuff through more in the future.

Never a bad idea to throw another 240V circuit into a garage when you're building. Some forward-thinking can backfire,* but if you're smart then it's best to do it while it's cheaper.

*A friend was planning a major renovation of his home (loved the neighborhood but needed more of everything) and was showing me the planned data closet he was putting in with ethernet running throughout the house. By the time construction was completed he was running WiFi everywhere and the ethernet ports sat unused.

 

[yosupitscel]

As others have stated, I would rule out aluminum and only consider the copper options. Copper is a better conductor and more thermally stable, and the wall charger requires copper at the connection. For a long run, you could use aluminum and switch to copper at the end using proper connectors, but in this case the run is so short it's not worth it to use aluminum.

The two options presented are 50A and 70A. The Rivian charger maxes out at 48A which requires a 60A circuit. You can use it with a 50A circuit, but then you have to limit the charging current to 40A by setting the DIP switches in the charger during installation. The vehicle will also charge a bit slower on a 50A circuit. I personally wouldn't go with a 50A circuit for a new install, but if your daily usage is low and/or installation cost is a concern, it's an acceptable option.

50A option - This quote is likely for #6 NM-B (non-metallic sheathed cable) which supports up to 55A, but the standard breaker size is 50A since the wire doesn't support 60A. 6-2 NM-B is about $4/ft, so with the breaker we're talking maybe $200 in material and half a day of labor. Not sure how much labor costs are by you, but I wouldn't expect total cost to be over $700.

70A option - There's various wire options resulting in a large price range. They could be quoting you #4 NM-B or SER (service entrance cable) which is rated for 70A but it's expensive in copper ($10/ft) and includes an extra conductor for neutral that you don't need for an EV charger. This wire is readily available but not the best option since the Rivian wall charger doesn't support #4 wire (it's too large).

You could do #6-2 MC (metal clad cable) which is rated for 75A, but it isn't commonly used in residential applications. I don't think this is what they are offering you, otherwise they would've listed it as 75A instead of 70A. This is probably your best option at $4/ft and it's relatively easy to run.

Or you could use #6 THHN with a #8 ground which is what I did, but THHN requires a conduit so labor costs are higher and therefore might not save much. It's a lot harder to run conduit through framing compared to a standalone NM or MC cable. My basement is unfinished and the run was about 80' so this worked well for me. But all these "70A" options should still cost around $1000.

Your quotes of $3-4K are excessive. You should be able to find an electrician that can do a 60A circuit in copper for a third of that price.

 

[Donald Stanfield]

Thanks everyone for your input

This is pre drywall. Main panel is on left of the door and I am planning to have Outlet around highlighted blue area so that I can park rivian on right and any future ev can be parked in reverse if needed. Hardly 35ft even from Main panel.

Do you guys advise to get subpanel intalled around the highlighted blue mark and get it taken care afterwards?

Let me see the ceiling joists. I can tell you that from the picture I can see it's not going to be as simple of a run as it looks because of that door, headers on a bearing wall and the way the joists are constructed. You can't drill through certain things but I would need a better picture of the ceiling to be sure.

 

[evguy]

Never a bad idea to throw another 240V circuit into a garage when you're building. Some forward-thinking can backfire,* but if you're smart then it's best to do it while it's cheaper.

*A friend was planning a major renovation of his home (loved the neighborhood but needed more of everything) and was showing me the planned data closet he was putting in with ethernet running throughout the house. By the time construction was completed he was running WiFi everywhere and the ethernet ports sat unused.

Well, now your friend is set up for wired backhaul on a mesh wifi network! That's no small thing.

 

[docwhiz]

I wired my new house with empty "smurf" conduit to main rooms and installed Ethernet cable. TVs and office computers/printers benefit from a wired connection. WiFi covers everything else. I have about 8 wired connections.
The conduit to the crawl space makes it easy to upgrade to different wiring if/when required.

Sponsored