For the following, we'll have an electrician do the work, but we want to keep costs down, so I want to double-check the proposals against what is possible.
Current
There are two buildings. In the one building there are 11 garages and 4 sheds. In the other building is the utility panel that feeds them. The panel is 100A and has very little continuous load on it, but does have a heat pump and electric water heater on it. There are 6x 20A breakers for the garage building. The conductors run through a 150' 1" PVC pipe, where the pipe is buried for the 60' between the buildings.
Desired
Provide the infrastructure to support EV charging in all the garages. Install EV charging in one stall now. We need to be able to load share among the EVs (maybe not initially, but we have to plan for it, probably via EVSE load management). We need to be able to load shed EV charging if the load on the utility panel is too high.
Proposal
In my research it seems that 3x 2 AWG wires will fit in that 1" pipe, which would give us 100A @ 240V out to the garages over that distance. We could install a grounding rod at the garage building. We could then install three boxes on the garage building:
- Something like a DCC-10 (https://rve-usa.com/products/dcc-10/)
- A 120V panel for the existing garage load
- A 240V panel for the EV load
Since we only have one pipe, my limited research indicates that if we get correctly shielded signal wire, we can put 4x 14 AWG wires in the pipe to do load sensing at the utility panel (per the DCC-10 wiring diagram) so that we can shed the EV panel load and not affect the garage panel load.
Limits
- It is not cost effective to change the pipe.
- The garages aren't deeded and can change occupants at any time, so we aren't interested in using the existing unit meters for electrical metering. We'll have to do that with the EVSE or some other (undecided) means.
- We can't overload the existing 100A utility panel.
- We can't shed any load but the EV (i.e. the garage door openers can't be part of the shed load).
Does the proposal sound like it would work? What considerations should I keep in mind? What kind of shielding would I need on those control wires? What else have I missed or gotten wrong?
