Is there a 40 amp charging solution for home?

You can set the DIP switches in the HPWA to 40,50,60,70,80,90 or 100A breakers - is that an option or is it an unneeded expense to get a HPWA? You could then potentially upgrade to the full 80A in the future if you wanted. Or couldn't you just terminate with a plain old 240V socket like at your dryer? I think I got an adapter for that plug with the car.

That is correct. 14-50 adapt.That's what I use.

If you don't want to spend for an HPWC, Tesla sells a couple of adapters for 30-amp outlets for the UMC:

Tesla Gear Shop NEMA 14-30

Tesla Gear Shop NEMA 10-30

I assume that would then work with your 40 amp wire. Note: I'm not an electrician by any means!

hemants said:

wouldn't a 1450 try to draw 50 amps and trip the breaker?

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You can set the maximum current in the Tesla's UI.

And I think the breaker is generally somewhat higher than the expected maximum current. For the HPWC I believe the max current is 80A but they recommend a 100A breaker. Any idea what breaker you have for your sauna.

Note, OP is in Canada. I am total unfamiliar with the CEC (Canadian Electrical Code) - my comments below relate to NEC (US National Electrical Code), but, as I understand, CEC is similar.

hemants said:

Want to put Nema 14-50 but my panel is not in a great location vs the garage so will be quite expensive.

However, I do have a dry sauna that is never used that is right beside the garage wall that has a 40amp wire to it.

If I could split this service with a manual either/or switch and take it to the garage I would be in pretty good shape.

What would I terminate it with?

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To confirm, you have a 40A (not 50A) breaker on this circuit, and there is no outlet at the other end (the sauna is hard wired)?

wayner said:

You can set the DIP switches in the HPWA to 40,50,60,70,80,90 or 100A breakers - is that an option or is it an unneeded expense to get a HPWA? You could then potentially upgrade to the full 80A in the future if you wanted. Or couldn't you just terminate with a plain old 240V socket like at your dryer? I think I got an adapter for that plug with the car.

Click to expand...

FYI, it appears that new HPWC's have a different encoding for the DIP switches (now 15/20/30/40/50/80/100 amps; 60/60/90 dropped, 15/20/30 added):
Tesla HPWC On EBay from Canada - Page 3

hemants said:

wouldn't a 1450 try to draw 50 amps and trip the breaker?

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NEC only allows a 14-50 outlet to be powered by a 40A circuit when the connected appliance is rated for <40A. Since the Model S can draw more, I don't think an inspector would allow a 14-50 to be installed here, unless the wire is large enough to support a 50A breaker and a 50A breaker is installed.

mikeash said:

If you don't want to spend for an HPWC, Tesla sells a couple of adapters for 30-amp outlets for the UMC:

Tesla Gear Shop NEMA 14-30

Tesla Gear Shop NEMA 10-30

I assume that would then work with your 40 amp wire. Note: I'm not an electrician by any means!

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I am 95% sure that NEC does not allow installation of new 10-xx outlets, since they are technically ungrounded (despite the fact that Home Depot/Lowes have bins of 10-30 and 10-50 outlets).

wayner said:

You can set the maximum current in the Tesla's UI.

And I think the breaker is generally somewhat higher than the expected maximum current. For the HPWC I believe the max current is 80A but they recommend a 100A breaker. Any idea what breaker you have for your sauna.

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It's not a "recommendation" - it's a code requirement under the National Electric Code. Continuous loads (EV's are always considered a "continuous load") cannot draw more than 80% of the circuit (breaker/wire) max rating.

You need to talk to an electrician, but I see a few options here:

1. If the wire in place has a neutral (4 wires total; hot 1, hot 2, neutral, ground), you could install a 14-30 outlet and replace the breaker with a 30A. If the wire is big enough, you could install a 50A breaker and a 14-50 outlet.
2. If there is no neutral (3 wires total, hot 1, hot 2, ground), your limited to a 6-xx outlet (for which there are no adapters) unless you replace the wiring, in which case you'd just install a 14-50.
3. Install a hardwired EVSE (HPWC or J1772).

If the sauna doesn't need 120V, it was probably wired without a neutral (saving money on wiring). I'm thinking your best option is to install a HPWC, set it for a 40A breaker, and charge at 32A max.

The OP said 40 amp wire, so I assume it is a 40 amp breaker. If so, DO NOT terminate it with a NEMA 14-50, that is dangerous, against code, etc.

In this situation, I would get a transfer switch that can handle 40 amps, route the breaker wire through that, and connected to the sauna on one switch leg and a NEMA 14-30 (30A) receptacle on the other, and then get Tesla's NEMA 14-30 adapter. That is assuming four wires were actually run to the sauna (2 hots, a neutral and a ground). The only (minor) problem here is that the breaker would be oversized for the receptacle, but this would work OK in practice.

If only three wires were run, then the best you could do would be to use a NEMA 10-30 receptacle, but now you would really be pushing it since the 10-30 neutral connection would have to be connected to the (presumably) bare ground wire, and if the 10-30 receptacle were used as a 10-30 in the future for something other than Tesla charging, you'd potentially have current running over than bare wire. Not good.

The previous post where the person recommended using an HPWC is the only truly 100% code compliant way to do it.

Personally, I'd run a new wire - it'll probably end up being cheaper, and certainly would work better in practice (no funky switch that no one knows about except you).

tga said:

I am 95% sure that NEC does not allow installation of new 10-xx outlets, since they are technically ungrounded (despite the fact that Home Depot/Lowes have bins of 10-30 and 10-50 outlets).

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Ah nuts. The convenient availability of a large number of such outlets for purchase online made me think it had to be legal.

tga said:

NEC only allows a 14-50 outlet to be powered by a 40A circuit when the connected appliance is rated for <40A. Since the Model S can draw more, I don't think an inspector would allow a 14-50 to be installed here, unless the wire is large enough to support a 50A breaker and a 50A breaker is installed.

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I'm not so sure about that. A 14-50 outlet is an advertisement of a 50A circuit. The assumption is the wire gauge and breaker behind it are all rated for 50A. However, if you go above 80% of the breaker's rating (40A) for more than 1 hour, it should trip the breaker. You should be able to use all 50A of it, but not for over 1 hour.

If the OP has a 40A breaker with proper wire gauge, there shouldn't be a problem putting a 30A breaker on it and running it at 24A (80%). Since there is no 40A plug available and putting a 14-50 to that circuit would violate NEC, the only way to hardwire is with an HPWC which would need to be dip-switched down to 30A (even though it could be switched to 40A and lower the amps in the car to 32A).

The best thing for the OP to do is to find out the gauge of wire going to the sauna and the breaker rating. If the wire can handle a 50A breaker, I would just put a 50A breaker and 14-50 on the end and be done with it. If you want to switch back and forth between charging the car and running the sauna, put a 14-50 plug on the end of the sauna's hardwires and switch them when you want to use them. You might be able to put a switch in the middle between the sauna and the car, just make sure it's properly rated for the amperage. Go over a bit to be on the safe side, too.

mikeash said:

Ah nuts. The convenient availability of a large number of such outlets for purchase online made me think it had to be legal.

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Replacement of an existing outlet may be OK, but I'm not sure. Where's FlasherZ when you need him?

Chris TX said:

I'm not so sure about that. A 14-50 outlet is an advertisement of a 50A circuit. The assumption is the wire gauge and breaker behind it are all rated for 50A. However, if you go above 80% of the breaker's rating (40A) for more than 1 hour, it should trip the breaker. You should be able to use all 50A of it, but not for over 1 hour.

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I haven't seen one in person, but anecdotally, I've heard of newer homes with 14-50's for electric ranges, wired with a 40A breaker and 8 Ga wiring. Mine (built in '04) has a 50A breaker and 6Ga.

There was some discussion of this here: Need some electrical help

hemants said:

Want to put Nema 14-50 but my panel is not in a great location vs the garage so will be quite expensive.

However, I do have a dry sauna that is never used that is right beside the garage wall that has a 40amp wire to it.

If I could split this service with a manual either/or switch and take it to the garage I would be in pretty good shape.

What would I terminate it with?

Click to expand...

If and only if the wire is rated to 50A, you would terminate it with a NEMA 14-50 receptacle as posted. The rating is for transient loads. For continuous loads, it is derated to 80%, so you'd run it at 40 A for routine charging.

Since there are no 40a receptacles, you have no choice but to use a 50a one on a 40a circuit. When my Blink was installed, they used 40a wiring/breaker and a 6-50 receptacle. A receptacle doesn't tell you what amperage the circuit can provide. There's always the chance that some other appliance is also attached to the circuit, or the breaker is smaller. The only thing you can be sure of is that the receptacle is rated high enough so that the breaker adequately protects it.

To the OP: Define expensive. Electrical connections are not a place to economize. You don't want to save a couple of thousand, but lose the house...or worse.

You should not let it hang like that. I purchased the cradle from a guy on this site for about $40 that will hold the unit to the wall so it doest put stress on the plug. IF the plug has any separation from the attached cable (problems in the past) it will create a fire hazard. I have a cradle and hooks at my installation to hold the charging unit and wrap the cable when not being used.

http://www.teslamotorsclub.com/showthread.php/34506-Organize-your-UMC-Controller-Wall-Bracket

muleferg said:

That is correct. 14-50 adapt.That's what I use.


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hemants said:

To clarify, the Sauna breaker is rated at 40 amps. I am presuming the wiring is also rated at 40 amps. Looks like Nema 14-30 would be the easiest solution with an either/or switch added to divert power from Sauna to garage. (never use the Sauna but would need capability for resale)

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The 14-30 is the correct solution. You'll have to check with your electrician to see if switching it like that is allowed. Local interpretations being what they are.

hemants said:

To clarify, the Sauna breaker is rated at 40 amps. I am presuming the wiring is also rated at 40 amps. Looks like Nema 14-30 would be the easiest solution with an either/or switch added to divert power from Sauna to garage. (never use the Sauna but would need capability for resale)

Click to expand...

I wouldn't be so sure of that - if that wire is only feeding the heating element, there's a really good chance it doesn't include a neutral, which means a 14-30 is out. You can't (legally or safely) install a 14-30 without a neutral, and you definitely can't tie the ground wire to the neutral and ground pins in the outlet.

I'm assuming you can't (legally) install a new 10-30 outlet (240/120 ungrounded) per CEC. That leaves you with a 6-30 (240 grounded) for which Tesla does not make an adapter.

You could install a HPWC ($750 US) or a hardwired Clipper Creek HCS-40 ($590 US) on a 2 wire 240V circuit w/ ground. Both need just L1/L2/ground, and both will let you charge 33% faster than a 14-30 would (32A vs 24A). For an extra $160, the HPWC eliminates fumbling with the J1772 adapter (or buying a spare). I don't know what the Canadian prices are; aren't there some rebates?

You can't install a 30a receptacle unless you downgrade the breaker to 30a to match it...which probably isn't enough for the Sauna. I'd do the HPWC, set to charge at 32a to match the 40a breaker. It would be hard wired so you don't have to worry about the receptacle.

If you truly don't use the Sauna, I'd disconnect it rather than mess with switches. You'll probably take the EVSE with you if you move, and you can reconnect the Sauna then...or bite the bullet and have a second circuit run at some point.

Chris TX said:

A 14-50 outlet is an advertisement of a 50A circuit. The assumption is the wire gauge and breaker behind it are all rated for 50A.

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One would think! And one of my disagreements with the NEC for allowing homes to be built with 14-50 receptacles to power ovens/ranges with Romex 8-3 on a 40A 2-pole breaker just so the starving new home builders can save a buck on copper. SCHEESH!! And be careful of dryer 14-30's with Romex 12-3 on a 20A 2-pole too.

linkster said:

One would think! And one of my disagreements with the NEC for allowing 1,000s of homes to be built with 14-50 receptacles to power ovens/ranges with Romex 8-3 on a 40A 2-pole breaker just so the starving new home builders can save a buck on copper. SCHEESH!! And be careful of dryer 14-30's with Romex 12-3 on a 20A 2-pole too.

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^^ This! It is very common to see stove setups with 14-50 outlets, but only 40 amp wiring and breaker. A bit of a head scratcher as to why it's allowed. Because EVs are considered "continuous loads", the 80% rule applies and the most you can draw from a 40 amp circuit is 32 amps (40 amps from a 50 amp circuit).