I am doing something similar to Running Service to Outbuilding. I tried asking for clarification there, but couldn't figure out how to. Sorry to start a new Q. If there is a better way, I'd appreciate feedback for the future. Also, FYI, this is asking for details related to a broader question I asked (400 Amp service to 225 amp and 150 amp panels). Hopefully, the below reflects what I learned there :)

I have a 2 car detached garage in Washington state, across a dirt county road from the main house (50-75 feet - need to measure). I want a 70 amp feeder to it (50 amp 240v car charger, 2 garage door openers, well pump, lights, GP receptacles). I've tried to plan the best I could based on the previous post and reading NEC 2020. I'd appreciate feedback on my plans, detailed below.

I believe I need a disconnect at the garage, so I'm planning a panel with a 70A main breaker, and 3 breakers for 3 branch circuits. E.g., Eaton BRP10B100, BR270, BR250, BRP115A1CS, and BR120. I don't also need a disconnect on the outside of the garage, do I?

I plan on running wires from the main house in a 1" PVC conduit in a trench 20" deep with 2" of sand, then the conduit, then sand, then dirt back to grade. I plan on using 3 wires of 4 AWG AL XHHW-2 and one 8 AWG solid copper wire. I believe I also need an 8 AWG solid copper wire to a copper grounding rod at the garage.

Similar to the $3K+ 400 AMP Meter Combo on the other question, I plan on using a much less expensive version, the Siemens MC0816B1400RLTM. The description of this says "This 400 Amp meter-load center combination is provided with one 200 Amp main breaker that feeds an 8 space, 16 circuit interior with feed-thru lugs that can be used to feed a load center down stream." Does that mean I can add lugs downstream of the 200A breaker and have my feeder wires connected there? Or do I first need another 70A breaker installed after the 200A breaker and before the feeder wires?

  • One more note. On two of the XHHW-2 wires, I believe I need three bands of electrical tape on each end: one with white (for the neutral), and one with red (for the second hot? not sure of correct term). Is that right? I can get colored XHHW-2, but only in 500 or 1000' spools. Aug 12 '20 at 16:59
  • Is the road between the house and garage public or private? If public, it may honestly be easier to get a second service placed there. You would have to deal with right-of-way permits, and locating your private utility in the pubic right-of-way whenever someone wants to dig in the vicinity. Aug 12 '20 at 17:15
  • It is a public road (county road). I originally asked about a 2nd service. That becomes costly each month, as there is a minimum monthly charge for each service. I doubt anyone would want to dig there - it's a public road, but my house is on one side, and my garage on the other. This is one of many houses built similarly on this road. With that said, I will definitely check with the county what is involved in doing this. Aug 12 '20 at 17:20
  • Reading more, I think I need 2 AWG XHHW-2, not 4. I was looking at the 90C column. I also saw comments about going up to 1 or 1/0 for futureproofing. What conduit size do I need for 2, 1, or 1/0? Aug 12 '20 at 17:22
  • One more question. Any requirement or even recommendation for the width of the trench? Aug 12 '20 at 17:39

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