Pre wire for EV charger

[mmcool]

I am getting a new home, it comes with pre wire for ev charger - 50 amp. When I asked builder for tesla charger , he mentioned tesla universal charger requires 60 amp. Have few questions -

1. Are there other good chargers which will work with 50 amp?

2. What component would be needed to upgrade it to 60 amp?

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[emoore]

I don't own a universal tesla charger but the Rivian charger (and probably others) have dip switches you can set to lower the amperage based on your circuit.

 

[NowOrNever]

Your builder is only partially right. The Tesla Universal Wall Connector is capable of 48 amps. That requires a 60 amp circuit (you can use 80% of the circuit rating for safety purposes). It can also be set to lower levels, however. Mine is installed on a 50 amp circuit and limited to a 40 amp draw. Part of the setup process allows you to select what amperage.

The limiting element is the wiring. You need either 4 ga. romex or 6 ga THHN wiring for a 60 amp circuit for an EV charger. Since you will pull 48 amps continuously, using 6 ga romex is not adequate. Many builders and home electricians routinely use 6 ga romex on 60 amp circuits (it is rated for 55 amps) using the "round up rule". Be sure to inform your builder that this will not work for an EV charger. BTW, I suggest the THHN in metal conduit installation. The 4 ga romex is kind of large for the connectors inside the Tesla charger.

I thought I had properly spec'd the wiring when we built our house three years ago. When I went to install my charger a couple of months ago I was surprised to find 6 ga romex. It forced me to use a 50 amp circuit instead of 60 amp. That means that you are delivering at a rate of 9.6 Kw instead of the maximum of 11.6. However, I should say that it is really not a big problem. I can still charge completely overnight.

I highly recommend the Tesla Universal Wall Connector. It works great and is easy to use with either the CCS or NACS port.

 

[SANZC02]

I am getting a new home, it comes with pre wire for ev charger - 50 amp. When I asked builder for tesla charger , he mentioned tesla universal charger requires 60 amp. Have few questions -

1. Are there other good chargers which will work with 50 amp?

2. What component would be needed to upgrade it to 60 amp?

He is incorrect, it can use a 60 amp circuit but is not required and can be set to 50 amps.

 

[Redline]

I have a 100amp panel in my garage just for EV charging. 50 for each vehicle. Works just fine.

 

[mmcool]

He is incorrect, it can use a 60 amp circuit but is not required and can be set to 50 amps.

Thank you all for replies. It is good to know that with 50 amp tesla charger will work with slight drop in charging speed. I have a follow up, builder is providing nema 14-50 receptacle. How hard would it be to replace that with tesla wall charger?

 

[mikehmb]

Thank you all for replies. It is good to know that with 50 amp tesla charger will work with slight drop in charging speed. I have a follow up, builder is providing nema 14-50 receptacle. How hard would it be to replace that with tesla wall charger?

Have the electrician recess the box into the wall, then you can direct wire from the EVSE into the wall. You can have them terminate the wiring in the box and not waste a perfectly good NEMA 14-50 that you'll end up throwing out.

Any competent electrician can do this.

As stated above, be sure to set the DIP switches to 40a max draw on the charger to conform to code (rated circuit minus 20%).

In fact, if you explain to your contractor that the EVSE is DIP switched to 40amp, I'm sure they can do it for you at build time.

 

[beatle]

I replaced my self-installed 14-50 with a Tesla UWC, but I had a fair amount of extra wire in the wall. That's an unlikely situation with a pro doing the job and you may be too short to reach where the UWC will go without turning the 14-50 location into a junction box where you extend the wires. I'm not even sure you can do that for an EVSE circuit.

You could have him run 6/2 to the location where you want to have the UWC installed and leave some extra so you can route the wire into the UWC and terminate it there. Running 6/2 will be moderately cheaper than the 6/3 he'll need to run for the 14-50 since he'll need a neutral for the receptacle, but an EVSE doesn't need one. The 14-50 will need a GFCI breaker which is more expensive than the normal one needed for an EVSE with integrated GFCI protection.

 

[Shmoe]

I don't own a universal tesla charger but the Rivian charger (and probably others) have dip switches you can set to lower the amperage based on your circuit.

you actually do it with the Tesla One installer app or the Tesla app itself now by connecting to an ssid the wall connector broadcasts.

Gen2 had the dip switches, Gen3 (including the universal) do it via software.

i have 2 universal wall connectors here with dedicated 60 amp home runs. They powershare 60 amps. It splits 30/30 if both cars are charging otherwise they can get the full 48 amps.

 

[PWHesson]

For new construction, have it wired for something larger. We just put in a Charge
Point flex. It will draw 50 amps so you really need a 70 amp breaker for continuous duty. I had already connected a new plug to our prewire so that I could charge the R1S with the portable charger. Had the new one tapped in to the panel with a short conduit run. Still have a Rivian charger NIB that I am trying to return...

 

[slillie]

I am getting a new home, it comes with pre wire for ev charger - 50 amp. When I asked builder for tesla charger , he mentioned tesla universal charger requires 60 amp. Have few questions -

1. Are there other good chargers which will work with 50 amp?

2. What component would be needed to upgrade it to 60 amp?

Whatever you decide, my advice is: Do not hardwire your charger. Having a 14-50 receptical gives you the flexibility to easily move your charger around in the garage AND you can easily remove the charger and take it with you on long trips. A lot of Airbnb's advertise now with 14-50 receptacles.

Regardless of what anyone says, a NEMA 14-50 receptacle for your charger is just as safe and just as efficient as being hard-wired in.

 

[Zoidz]

Whatever you decide, my advice is: Do not hardwire your charger. Having a 14-50 receptical gives you the flexibility to easily move your charger around in the garage AND you can easily remove the charger and take it with you on long trips. A lot of Airbnb's advertise now with 14-50 receptacles.

Regardless of what anyone says, a NEMA 14-50 receptacle for your charger is just as safe and just as efficient as being hard-wired in.

If you use a NEMA 14-50, I highly recommend using Hubbell 9450A. Leviton has cut corners on their outlet, and the Amazon cheap non-name stuff is garbage. Saving $35 and burning up the wiring or your house is a poor decision.

 

[Shmoe]

Whatever you decide, my advice is: Do not hardwire your charger. Having a 14-50 receptical gives you the flexibility to easily move your charger around in the garage AND you can easily remove the charger and take it with you on long trips. A lot of Airbnb's advertise now with 14-50 receptacles.

Regardless of what anyone says, a NEMA 14-50 receptacle for your charger is just as safe and just as efficient as being hard-wired in.

If you want to be stuck at 40 amps, sure.

 

[Zoidz]

If you want to be stuck at 40 amps, sure.

For many people who charge at home overnight, being "stuck" at 40 amps is just fine. 48 amps is at best a 20% improvement over 40 amps (actually less due to heat losses), translating into 1 to 2 hours shorter charge time.

 

[Shmoe]

For many people who charge at home overnight, being "stuck" at 40 amps is just fine. 48 amps is at best a 20% improvement over 40 amps (actually less due to heat losses), translating into 1 to 2 hours shorter charge time.

1-2 hours can be the difference on a long commute vs not having to fast charge. But I hear you.

you said “don’t let anyone tell you” but you couldve mentioned that limitation too

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