New Construction - Need Help with Exact Phrasing for Garage Charging

[GadgetGary]

I am likely going to buy a new construction home that is currently framed and wrapped. I want NEMA 14-50 outlets, one on each side of the garage (to use mobile chargers x 2 at the same time.) What exact phrase should I have added to the contract?

"Seller will install a NEMA 14-50 outlet on each side of the garage with a dedicated circuit for each outlet"

Is the last part about dedicate circuit necessary? Do I need to specify the amperage it's capable of? I assume I want 50 amps running per outlet? Thanks!

 

[Sophias_dad]

Yes, the dedicated circuit is necessary. If the professional is being 'professional' it shouldn't be since you aren't allowed to put two such outlets on the same circuit, but having it in writing is way better than not.

Technically the mobile charger(connector) will only take 32 amps continuous so the 14-50's could be installed as 40 amp outlets. Its better to specify them as 50 amp service anyway. There's the 'Corded mobile connector' which will expect a 50 amp circuit.

You should also specify they should be GFCI breaker equipped.

Maybe "Seller will install a 50 amp NEMA 14-50 outlet/wiring on each side of the garage with dedicated GFCI circuits for each outlet"

 

[240vPlug]

Gary, I would advise to have 60 amp circuits installed and to hard wire your chargers. Its a safer solution than 14-50 outlets and you will not need GFCI breakers for the circuits. They can install a rough-in for 60 amp circuit in each location. The wiring will all be there all you will need to do is install your wall connector. You will be able to charge at 48 amps and you could even setup power sharing.....which if you have 200 amp service may be required if you have all electric appliances since the service may not be enough to support two dedicated 50 amp EV charging circuits.

I have 200 amp here and I have two 60 amp circuits setup for power sharing. They share 60 amps total power between the two of them. One at a time they can charge at the full 48 amps but if I have two cars plugged in and charging at the same time it will intelligently share the 60 amps of available capacity.

 

[Sophias_dad]

Unless you have more than 200 amp service, there may be significant concerns of overload if you have two uncoordinated 32 amp loads running at once. I'd also agree with @240vPlug that the better solution is dual HPWCs. If you are concerned about having a j1772 car in the future, you could get one Tesla-ended HPWC and on J1772-ended HPWC and they'll still share power information.

If you go down the 60Amp path, be sure to make it crystal clear they are intended for continuous use. If you don't do that(or they ignore it or just don't understand the ramifications of continuous use), they'll probably put in 6 gauge romex that will not be code-compliant carrying more than 44 amps continuously, or having more than a 50 amp breaker. If it were an intermittent use circuit(welder, usually) it could have a 60 amp breaker.

 

[Cosmacelf]

I’ll second or third the suggestions to plan for using Tesla Wall Connectors (which you can buy in either Tesla or J1772 handles). So ask for 60A circuits, regular breakers. As others have said, gives you the option to load balance between the two if needed. And it gives you faster charging. And it removes a fault point (the receptacle).

Although you shouldn’t have to say it, many, many electricians install 60A circuits incorrectly in that they use 6 gauge NM-B cable (“romex”) for such, even though it is only rated for 55A. Ask for PVC conduit and 6 gauge, or MC cable and 6 gauge.

 

[Sophias_dad]

Ask for PVC conduit and 6 gauge, or MC cable and 6 gauge.

Or 4 gauge NM-B

 

[davewill]

The wording in the contract should specify they are for EV charging and 50a. Code is different for EV charging (notably the expensive GCFI breakers), and if the circuits are found to be not installed to code for EV use, you'd be able to come back to them.

 

[Cosmacelf]

Or 4 gauge NM-B

I don’t think 4/2 NM-B exists and 4/3 is hard to come by and is expensive, and wrangling 4 gauge is a pain in the butt if you have an option to use 6 gauge.

 

[Sophias_dad]

I don’t think 4/2 NM-B exists and 4/3 is hard to come by and is expensive, and wrangling 4 gauge is a pain in the butt if you have an option to use 6 gauge.

I agree, I've never seen 4/2 NM-B. I've never worked with 4/3, but I'm sure its a pain. That said, running a ton of (non-flex) conduit would be a pain too.

 

[jcanoe]

For new construction consider installing a 125 amp sub-panel in the garage. From the sub-panel specify (2) 240V, 50 amp dedicated circuits and perhaps an extra 20 amp utility circuit. Alternately you could install (2) 60 amp circuits from the sub-panel for use with separate Tesla Wall Connectors. (The Tesla Wall Connector can be configured for automatic load balancing.)

Depending on the distance from the Service Panel to the garage using aluminum wire from the Service Panel to the Sub-panel would save you some money. I have a single 50 amp circuit and a 14-50 in my garage (70 ft run, installed in 2016) but knowing what I do now I would install a sub-panel and the Wall Connector.

 

[howardnj]

For new construction consider installing a 125 amp sub-panel in the garage. From the sub-panel specify (2) 240V, 50 amp dedicated circuits and perhaps an extra 20 amp utility circuit. Alternately you could install (2) 60 amp circuits from the sub-panel for use with separate Tesla Wall Connectors. (The Tesla Wall Connector can be configured for automatic load balancing.)

Depending on the distance from the Service Panel to the garage using aluminum wire from the Service Panel to the Sub-panel would save you some money. I have a single 50 amp circuit and a 14-50 in my garage (70 ft run, installed in 2016) but knowing what I do now I would install a sub-panel and the Wall Connector.

That is exactly what the NJ licensed Tesla recommended and did for me. Approx 150 ft of 4 conductor aluminum cable from my basement 200 amp main panel thru my finished basement up to the attic above my garage and down to the 125 amp sub panel in my garage with 100 amp main breakers and 60 amp breakers for my Gen 3 HPWC and a couple of extra outlets below the panel