Wiring – Current Capacity of 6 AWG AL Type SE for an EV Charger

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We recently finished our basement and had electrician run a cable to the garage for an electric vehicle charger that terminates in a junction box in the garage. From the 200A panel the cable is connected to a 2-pole 40A breaker and connected to cable with the markings "APAR INDUSTRIES LTD 3 CDRS 6 AWG+ 1 CRD 6 AWG AA-8000 AL TYPE SE STYLE R 600V SUN-RES (UL) E498924 2022 10856 FT".

I'd like to purchase a charger with the most power this setup could support. Can the cable support a 40A charger with a change to a 50A breaker? Can it support more? Am I stuck with 40A breaker? In a perfect world I'd like a 48A charger. Any other options? Thank you!

Best Answer

6 AWG aluminum SE is good for 50A based on this ampacity table

That is enough for 40A continuous. EV charging is the epitome of a continuous load (it doesn't even cycle like HVAC or an oven will once they reach the target temperature).

40A is enough for roughly 29 - 37 added miles of range per hour of charging, based on this Tesla Wall Connector table. Your actual mileage will vary, but basically that is more than enough to charge a relatively "empty" (10% - 20% battery charge) EV overnight. Hardly anyone needs more than that on a regular basis.

A couple of other notes:

  • Do NOT use a receptacle. That is crazy in general and especially at higher charge rates. Use a Tesla Wall Connector or similar device hardwired.
  • The Tesla Wall Connector, and likely many other EVSE devices, can't handle aluminum wire directly. So you need something in between. You may also need a local (i.e., within sight) disconnect) though that varies. The simple solution to both problems is a disconnect box, such as a 60A "air conditioner" disconnect. Just make sure it can handle both aluminum and copper and that it is truly up to the task. One I just looked at says 60A but also says 7.2kW, which would only be 30A.
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