I have on old 30 amp hot water heater circuit in my house that is unused. How much charging could I get out of that? What is the best choice ? HPWC?
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For the ones that run on a 50A circuit, they won't supply more than 30A, even though they should be able to do 40A. They seem to be going for the non-Tesla vehicles, where their maximum onboard chargers are only about 6.6kw.
The thing that frustrates me a little about the Clipper Creek units is how much they derate from the circuit level, so you're not getting as much charging speed as you should be able to get. For ones that are running on a 30A circuit, they won't supply any more than 20A, even though they should be able to do 24A. For the ones that run on a 50A circuit, they won't supply more than 30A, even though they should be able to do 40A. They seem to be going for the non-Tesla vehicles, where their maximum onboard chargers are only about 6.6kw.
The easiest thing to do is to put in a NEMA 14-30 receptacle and then use the Tesla supplied UMC to plug into it.
I don't think a HPWC is supposed to be set up on a circuit that low. I thought it needs to be at least 50A. If your circuit is 240V 30A, I would think putting a NEMA 14-30 or 10-30 (depending on what wiring it has) dryer outlet on it would be a good plan, as Cosmacelf was alluding to. You can get an adapter to that from EVSEAdapters.
Neither is possible on a typical water heater circuit. Only a 6-series will work. Both 14-30 and 10-30 require a neutral (and you cannot use the EGC). 14-30 requires 2 hots + 1 neutral + 1 ground (EGC). 10-30 requires 2 hots + 1 neutral (no ground). 6-30 requires 2 hots + 1 ground (no neutral).
A 10-30 is two hots and a ground, and would absolutely work in this situation.
Disconnect the water heater and wire up a 10-30 outlet then get the UMC 10-30 adapter here:
http://shop.teslamotors.com/collections/model-s-charging-adapters/products/nema-10-30
Total cost for the outlet would be maybe $20-$30 in parts and $45 for the UMC 10-30 adapter.
NEMA 10 devices are a curious throwback to an earlier time. They are classified as 125/250 V non-grounding (hot-hot-neutral), yet they are usually used in a manner that effectively grounds the appliance, though not in a manner consistent with most modern practice.
I continue to be amazed at what people want to do to avoid installing a proper 50A circuit to charge their $80,000-$120,000 car.