Advice on pre-wiring my Garage

[pete8314]

Thanks, will do. I need to get a couple of quotes next, so will see what the difference is.

[FlasherZ]

I would recommend that you consider provisioning a 100 Amp circuit to the new charging location.

The major difference is that a 50A circuit can be placed on type NM-B 6/3 cable, while 100A requires THHN/THWN #3 in a conduit. The wire cost difference is roughly 2x the cost, but you have to figure in the conduit and installation for that conduit. If it is a short run (40' or so) your materials difference may only be $200. But if you're looking at a long run, you could have a significant expense in the different, and then you'll need to consider whether you'll use the high current or not.

[JackA]

pete8314: I would still check this with a licensed electrician familiar with your local code requirements. My entire materials bill was $453. I had 40 feet of conductor in 1 1/2 conduit, 20 feet of wire from the load center to a junction box where it changed to conduit and conductor plus a new sub-panel and the wire and breaker and connectors. I am not thinking that I would have saved very much by installing a 50 Amp circuit.... again, I am not an electrician.

[teslasguy]

I also ran a 100amp subpanel to my garage and then a NEMA 14-50 outlet off that. This I can now easily run another outlet for my wife should she also get an EV.


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[FlasherZ]

pete8314: I would still check this with a licensed electrician familiar with your local code requirements. My entire materials bill was $453. I had 40 feet of conductor in 1 1/2 conduit, 20 feet of wire from the load center to a junction box where it changed to conduit and conductor plus a new sub-panel and the wire and breaker and connectors. I am not thinking that I would have saved very much by installing a 50 Amp circuit.... again, I am not an electrician.

Your materials bill will be considerably less if you can use NM-B inside a wall. Wire cost is roughly half, plus you save the cost of the conduit. If you can't run inside a wall, Romex must be run inside conduit to protect it, so your only cost difference is the wire cost ($118 for 50' of 6/3 vs. $232 for 200' of #3).

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I also ran a 100amp subpanel to my garage and then a NEMA 14-50 outlet off that. This I can now easily run another outlet for my wife should she also get an EV.


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This is a good strategy if you think you'll need an EV at some point. I fed a 125A subpanel from my main panel, and that gives you room for an HPWC @ 80A + a 14-50 @ 40A. But that's because I know I need a high-amp charging solution - the cost differential would be several hundred dollars.

It's similar to the HPWC vs. 40A charging arguments -- every case is different and if you have the money it doesn't hurt... but for some people it's an extra $300 or so.