jake14mw
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Should I install a 20 amp 110 circuit along with my new 240??

Tue Jan 02, 2018 8:36 am

Hi all,

I am planning my install of a new 240 circuit for my Siemens level 2 charger. I have thought about the fact that I might get another electric car in the future, and am trying to plan for maybe charging two cars at once. I'm not trying to go crazy and install 2 240 circuits, but I am wondering if it would be smart to run another new 110 line into the garage while I am doing the new 240. Currently, I am charging my 2014 SL by plugging into an outlet in the ceiling in my garage used by a garage door opener. It is the only outlet that can reach out into the driveway. This circuit is shared by the garage door openers and three other outlets. So, I was thinking to run another 20 amp 110 circuit, so that the outlet would be more convenient to the driveway, and dedicated.

The wire run is just short of 100 feet from my breaker box. It will get run from the box in my basement about 45 feet in the open basement, then 25 feet behind a finished basement wall, and then out into the garage, and another 35 feet in the garage. The garage run would be on the wall surface protected by PVC. Does this cause any code issues? Does 20 amp with 12-2 wire make sense? The existing plan for the 240v circuit is to run 6-3 wire for that. Will my Leaf charge faster at Level 1 on a 20 amp circuit than 15? Thanks.
Last edited by jake14mw on Tue Jan 02, 2018 8:58 am, edited 1 time in total.

rmay635703
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Re: Should I install a 20 amp 110 circuit along with my new 240??

Tue Jan 02, 2018 8:50 am

Leaf can only charge as fast as the EVSE will allow, true for L1 or L2

If you are allowed to gang circuits you could just make one 10-4 run or possibly 8 gage then you should be able to supply current for multiple EVSEs

BrockWI
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Re: Should I install a 20 amp 110 circuit along with my new 240??

Tue Jan 02, 2018 8:59 am

Or if your running an 8-3 for the main EVSE I would add a 12-3 and two outlets. Then you could have two 120v 20 amp outlets or a single 240v 20 amp outlet if needed. Or you could just the 12-3 for a single 120v 20a outlet. The cost difference between 12-2 and 12-3 is very small compared to pulling the wire in the first place.
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LeftieBiker
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Re: Should I install a 20 amp 110 circuit along with my new 240??

Tue Jan 02, 2018 9:47 am

I was just thinking about this last night, except that my context is possible need for a battery maintainer if I put my 240 volt charging station out front instead of in the garage. A 20 amp 120 volt outlet would also be handy for things like my plug in electric chainsaw. Maybe we should reconsider omitting the Neutral in these runs...
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Foschas
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Re: Should I install a 20 amp 110 circuit along with my new 240??

Tue Jan 02, 2018 10:05 am


Tsiah
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Re: Should I install a 20 amp 110 circuit along with my new 240??

Tue Jan 02, 2018 10:27 am

rmay635703 wrote:Leaf can only charge as fast as the EVSE will allow, true for L1 or L2

If you are allowed to gang circuits you could just make one 10-4 run or possibly 8 gage then you should be able to supply current for multiple EVSEs

10-4 would be 3 conductors, a neutral and a ground. Too few conductors for a 240V outlet and a 120V outlet (unless he's Hard wiring the EVSE)

10AWG is too small for 27 amps. Especially constant load at 100 feet in Romex.
I ran 30ish feet to my 14-50 outlet on a 50A breaker and had to use 6-3 Romex because the current carrying capacity for Romex is lower than THHN wires in conduit.

Tsiah
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Re: Should I install a 20 amp 110 circuit along with my new 240??

Tue Jan 02, 2018 10:33 am

LeftieBiker wrote:I was just thinking about this last night, except that my context is possible need for a battery maintainer if I put my 240 volt charging station out front instead of in the garage. A 20 amp 120 volt outlet would also be handy for things like my plug in electric chainsaw. Maybe we should reconsider omitting the Neutral in these runs...

If you're hard wiring the EVSE that's not a problem. If you're installing an outlet, code requires the neutral to be at the outlet even if it's unused.

wwhitney
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Re: Should I install a 20 amp 110 circuit along with my new 240??

Tue Jan 02, 2018 11:35 am

Tsiah wrote: If you're installing an outlet, code requires the neutral to be at the outlet even if it's unused.

If you're installing a receptacle that provides a neutral (14-50) rather than one that doesn't provide a neutral (6-50).

Cheers, Wayne

wwhitney
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Re: Should I install a 20 amp 110 circuit along with my new 240??

Tue Jan 02, 2018 11:52 am

So are you going to get an electrician to do this or are you going to do it yourself? If you're getting an electrician to do it, they could run 6/3 MC cable or some other 75C wiring method; that has an ampacity of 65A and you could protect it with a 60A breaker. That would let you set a small 60A subpanel in the garage to feed multiple receptacles.

If you are doing it yourself, you probably want to stick with NM cable with its 60C ampacity. Cost-wise you'd be best off using 6/2 NM (the EVSE doesn't use a neutral, running it is a waste of copper), a 6-50 plug and receptacle (or hardwire the EVSE), and then maybe one 12/3 NM for a MWBC with two receptacles on it, one on each leg. Although maybe the MWBC would be too much complexity, you could just run one 12/2 NM for a single 20 amp circuit with a 5-15 duplex receptacle on it.

As to the OP, if you're going to the trouble to run the 6/2 (or 6/3) NM that distance, the marginal labor to also run the 12/2 (or 12/3) NM would not be great. Probably a good idea. As to code issues, if you use a single PVC chase for both cables (I suggest upsizing to 1-1/4" PVC for ease of installation), you'll have to derate the cables for bundling. But the way the numbers work out, that has no impact, see below for details.

Cheers, Wayne

Derating: NM cable is limited to the 60C ampacity for conductors, which for #6 Cu is 55A, and for #12 Cu is 20A. [And #12 is also limited for most circuits by the small conductor rule to a 20A breaker.] However, NM actually has 90C conductors inside of it, and for derating purposes you're allowed to take advantage of that. The 90C ampacity for #6 Cu is 75A, and for #12 Cu is 30A. The derating factor for 4-6 current carrying conductors is 80%, so the derated ampacities are 60A for the #6 Cu and 24A for the #12 Cu. These are both still greater than the 60C ampacities, so there is no net reduction in ampacity for the bundling.

GerryAZ
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Re: Should I install a 20 amp 110 circuit along with my new 240??

Tue Jan 02, 2018 2:02 pm

Wayne,

Thanks for the clarification on the 60C rules for NM cable with 90C conductors. I will remember that for future projects. You mentioned a 5-15 duplex receptacle for a dedicated 20-ampere circuit. Wouldn't you either need two (or more) 5-15 receptacles or a 5-20 receptacle to comply with Code on a 20-ampere circuit?

Another possibility for the OP: Run 12/3 and install a 20-ampere 2-pole GFCI breaker to feed a 6-20 (240-volt) receptacle and two 5-20 (120-volt) receptacles since it sounds like there are few existing receptacles in the garage. This would allow for high-rate charging from the 50A receptacle and slower 240-volt charging from the 20A receptacle for a second car (assuming adequate capacity in main panel).

Cheers,
Gerry
Gerry
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