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Suppose I have a duplex, building A, which has 2 electric services. It also has a detached garage structure, building B. Each tenant has half the garage. Weirdly, garage lights are powered from the house of a cooperative neighbor so are on neither service. That is the only service to the building and it cannot possibly carry EV loads.

Now, with EVs arriving, each tenant wants an EV charge station, and they understandably want it powered off their own meter.

How do we make that work legally per NEC? It seems like we will have 3 services to the building. Will we be forced into a new service there and doing "pay stations"?

Can the alien services come into the building if they only serve a hard-wired EV station?

Will it help if the EV stations are standalone stands just outside the garage? (It doesn't have doors anyway).

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    I do not plan to self answer. Nov 17 at 1:07
  • 230.2 (D) Different Characteristics - Additional services shall be permitted for different voltages, frequencies, or phases, or for different uses, such as for different rate schedules. would seem to allow for one of these because it is 240V, assuming the lighting circuit is 120V (and just a circuit, no panel in or on the garage). A bit of a twist would be to say make one of the circuits 240V/120V but AFAIK all reasonable EVSE are 240V-only devices. Another unlikely solution would be if the two EV users happen to have different Rate Schedules, but that's unlikely. Nov 17 at 1:28
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    "Lights powered by a cooperative neighbor" actually sounds like a violation, as tenant services are not suposed to supply power to shared/community spaces
    – Ecnerwal
    Nov 17 at 2:29
  • @Ecnerwal yeah, I reckon it is, however migrating the lights to a house panel wouldn't change the underlying question Nov 17 at 3:10
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    @manassehkatz-Moving2Codidact -- this would be an Article 225 situation not Article 230 most likely since I reckon the service drop/lateral isn't landing in the garage Nov 17 at 3:12

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I would call this OK but it depends on your AHJ's interpretation of "different uses"

NEC 225.30(E) permits a structure to be fed by multiple branch circuits or feeders that have "different uses":

(E) Different Characteristics

Additional feeders or branch circuits shall be permitted for different voltages, frequencies, or phases, or for different uses such as control of outside lighting from multiple locations.

I would call two separately metered tenants in the garage "different uses" myself. However, I am not sure what AHJs think of such a setup, as power to garages has not needed to be split among tenants like this until now.

Note that you'll need a local disconnecting means for each branch or feeder to the garage to comply with 225.31, as well as a grounding electrode system at the garage tied to the equipment grounding conductors of all the branch & feeder circuits at their respective disconnects. (The good news is that since EV chargers don't use neutral, you can use bog-standard non-fusible air conditioner pullouts for the EV charging circuit disconnects.)

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  • Would that be a ground wire to two ground rods for each EVSE? Or one wire that gets to both EVSE and a single pair of ground rods? Nov 17 at 4:26
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    @manassehkatz-Moving2Codidact -- you'd have a GEC that runs to the disconnects, likely with taps to each individual disco Nov 17 at 5:04

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