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I recently added a Square D 50Amp 2pole breaker to my panel dedicated to add a NEMA 6-50R Outlet for a Chargepoint EV Charger. Everything works fine, but when I'm charging my car there are a couple of pot lights in my kitchen (LED bulbs) (that are on a different circuit than the EV charger) that don't turn on immediately (several minutes). The switch turns on 3 pot lights, but 2 of the 3 lights take a few minutes to turn on when I'm charging my vehicle. Is this something I need to be concerned with?

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    Could be funky lights or can be overloading your panel. 50 extra amps is a quarter of a 200 amp panel. Did you do a load calculation first? Depending on your location, that receptacle might be not in code since you do not have GFCI protection(or not mention) for it(why hard wiring is recommended).
    – crip659
    Feb 27 at 20:46
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    You installed the fastest load charger that your panel might not support.. If it is programable lower the load capability. If it is Tesla you can set the load current.
    – Traveler
    Feb 27 at 21:21

1 Answer 1

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LOAD CALCULATION!!!!!

You were supposed to do a Load Calculation BEFORE deciding how much power to provision for your EVSE (a.k.a., Car Charger). You didn't. Now you're paying for it.

An NEC Load Calculation takes into account:

  • Size of your house (square feet)
  • Large fixed appliances (e.g., electric water heater, EVSE)
  • HVAC (larger of H or C)
  • Cooking appliances (with some special rules)
  • Required dedicated circuits (e.g., kitchen)

and a bunch of other things. It results in a number which is the amount of power you can expect to use. It isn't "add up the breaker handles" (that would be a much higher number). It isn't "I never trip the big breaker, so I must be OK" (because you can overload quite a bit before you get to that point).

When you make significant changes to your electrical usage - and 50A is significant, you need to do a Load Calculation for:

  • Your entire service. Unless you have 400A/Class 320 service (and even then, if you have electric tankless water heating...) there is always a concern that another 50A (or possibly less) is just too much.
  • Your main panel.
  • If your EVSE (or other new stuff) is going to be fed from a subpanel, the subpanel (and any subpanels in between that subpanel and the main panel).

If and only if your Load Calculation is OK - e.g., 150A on 200A service, so you have 50A to spare, and the subpanel is 100A with 50A or less in use, etc. - can you add that 50A circuit for charging your car.

If the numbers don't work out the way you want them to then you have 4 choices:

  • Load Shedding - Any of a number of different automatic methods of monitoring and adjusting usage so that you don't go over the limits. You won't get 50A all the time but you'll get it a lot of the time, automatically.
  • Reduce the load - e.g., perhaps 20A instead of 50A, but still enough to charge 50% or more overnight.
  • Change something else - e.g., replace resistance heat with a heat pump or tankless water heating with a tank.
  • Rearrange things - this only works if the problem is in a subpanel but your total service and main panel are OK.

If you go through this process and the end result is that you are not going over the rated capacity of utility service, main panel or subpanel then we can look at other possible problems/solutions.

Assuming that the overall power problem is resolved:

Hardwire Your EVSE

A plug/receptacle EVSE (e.g., NEMA 6-50) requires a GFCI breaker in many locations (increases each year as states move to newer versions of the NEC). If you didn't put in a GFCI breaker then you might be violating code already. But change to hardwired and that problem goes away as the EVSE takes care of the GFCI by itself. (With a plug/receptacle connection there is the concern that you might unplug the EVSE and plug in something else that doesn't have its own GFCI protection.)

EV charging is also very hard on plugs and receptacles, which means that decent-but-not-super-fantastic quality receptacles often fail within a relatively short time. Hardwiring avoids that problem.

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  • Thank you for the detailed reply! I live in a relatively new cookie cutter community and many of my neighbors had installed Level 2 chargers, so I figured it would be OK. I have the charger set to 40A, but will look into reducing to 30A going forward. Thanks again!
    – GroundBeef
    Feb 27 at 21:40
  • There may be differences that you are not aware of in HVAC or other major appliances. Feb 27 at 21:53
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    @GroundBeef for all you know, those other stations are 16 amps. Feb 27 at 23:12

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