How best to set-up temporary power to easily convert to permanent power for new single family home?

Question

I'm building all-electric >2,000 sq ft single family home on a vacant 2 acre parcel in Northern California. My plan, which my local utility (PG&E) has approved, is to install a permanent customer owned (CO) pole about 15' from an existing PG&E pole near the corner of my property. The CO pole, which is approx 100' from the future house, will provide temporary power during construction as well as permanent power once the house is completed. A meter base and load center panel will be mounted on the pole (pedestal style) and the PG&E meter and main load center panel will stay there after conversion to permanent power. 200 amp permanent power will be undergrounded from the CO pole to a 200 amp interior subpanel at the house. PG&E intends to set up our temporary service from their side of the meter as if it was permanent service, so their transition from temporary to permanent power will just take an administrative/rate change.

Here are some additional details:

Permanent Customer Owned (CO) Pole: 25' 200A Class 6 PG&E Pole

Panel on Pole: As suggested in other post (Thanks ThreePhaseEel), considering the Milbank U5169-XTL-200 however open to other suggestions. A local power pole installer suggested a 200-Amp Cutler Hammer Meter Base & Load Center with 4 Space Circuits and 8 Single Pole Circuit, but it is not clear whether this can be used for permanent power.

Outlets at CO Pole: For temporary power, I probably only need one 20 amp circuit for two 110v outlets and one 30 amp RV outlet box. I'd like to keep these outlet in place once I set up permanent power to the house.

Temp Power Configuration: Given the CO pole and outlets will be over 100 ft from the building pad, I plan to run a 30 amp 100' connector cable from the CO pole to the pad and hook up a 30 amp spider box.

Feeder Line for Permanent Power to House: 350 KCMIL XHHW-2 aluminum wire feeder wire placed in 2" Schedule 80 PVC conduit. (Planning for 310A amperage capacity instead of 250A to address voltage drop along the 100' distance from main panel to subpanel.)

Subpanel at House: 40-space or 42-space, 200A, interior main breaker panel

Here is my main question: What is the most optimal way to configure the meter/load center panel for temp power so that minimal (if any) reconfiguration is needed when we hook up permanent power to the house? I received a couple bids for CO pole/temporary power install and I don't feel like I've gotten a clear answer about how best to convert the panel setup to permanent power (installers just focused on temporary power). At the minimum, I want a disconnect at the meter to cut off power to the house subpanel which is not a typical feature of temp power panel. Any input on any aspect of this project would be appreciated.

Thanks to those who contributed to Martin Vandepas's "Is it better to install temp service or permanent outdoor service with future home as subpanel?" thread which I've reviewed closely and incorporate responses there into my existing plan.

Answer 1

What you probably want is a Ranch Panel

That has several features.

• Optionally, a meter pan. (your call.)
• A 200A main breaker (or in the case of a 400A service, two of them, but only one connects to the below items; the other simply has lugs.)
• A mini-panel with 4-12 breaker spaces, fed off one 200A breaker.
• "Thru Lugs" also attached to the bus of the mini-panel.

This is perfect for your objective. In the standard intallation you come off the "Thru Lugs" to carry the full 200A to your main dwelling. The 4-12 breaker spaces are used to feed auxiliary loads or buildings - RV stand, well, shed, barn, shop, in-law apartment, etc. So you put your temporary loads in the breaker spaces, and use the feed-thru lugs for the final feeder to the house.

Panel on Pole: As suggested in other post (Thanks ThreePhaseEel), considering the Milbank U5169-XTL-200 however open to other suggestions. A local power pole installer suggested a 200-Amp Cutler Hammer Meter Base & Load Center with 4 Space Circuits and 8 Single Pole Circuit, but it is not clear whether this can be used for permanent power.

Those are all Ranch Panels. As is typical, the contractor thinks it's a great idea to pinch pennies by getting fewer breaker spaces. We couldn't disagree more here, because we see an endless stream of askers who are out of breaker spaces, because the last guy saved the price of a pizza.

Most ranch panels are 8 spaces. One or two are 12 spaces. Remember most of your circuits will be 240V and will take 2 spaces at a time. Smaller 240V circuits under 50A can be double-stacked using quadplex breakers.

Outlets at CO Pole: For temporary power, I probably only need one 20 amp circuit for two 110v outlets and one 30 amp RV outlet box. I'd like to keep these outlet in place once I set up permanent power to the house.

Yeah, that's just typical of the stuff you put in the "mini-panel" area of a Ranch Panel.

Temp Power Configuration: Given the CO pole and outlets will be over 100 ft from the building pad, I plan to run a 30 amp 100' connector cable from the CO pole to the pad and hook up a 30 amp spider box.

Keep in mind most spider boxes will expect a 4-wire NEMA 14-30 type socket, not the 3-wire "TT30" type used for small RVs.

For 100' distance I wouldn't even bother, and just run air hose or normal orange extension cords per tool. That way you're not investing in costly #10 cordage that you'll never use again.

Feeder Line for Permanent Power to House: 350 KCMIL XHHW-2 aluminum wire feeder wire placed in 2" Schedule 80 PVC conduit.

OK so you're the second guy today to do what I call a "bamp" or "randomly enlarging wire size as an emotional decision rather than actually do the calculation". These end badly - either in excessive voltage drop, or wasted money. In this case you flubbed twice: that wire is too big for 2" conduit, and the bump is gross overkill. Really, on 240V there's no point even doing the calculation til at least 170'. 4/0 (your absolute minimum assuming you never upgrade the service above 200A) is perfectly adequate. Even the wire salesman doesn't recommend a bump below 3% and 4/0 comes in at 1.56%. You might go 250 kcmil for in case you upgrade to a 400A service in the future. (the special rule allowing 4/0 no longer applies).

(Planning for 310A amperage capacity instead of 250A to address voltage drop along the 100' distance from main panel to subpanel.)

You're in the wrong table. You need to use Table 310.15(B)(16) which is now called 310.16, and you use 75°C column for any wire type you would use here. (NM and UF are 60°C wire but are not options here)

At the minimum, I want a disconnect at the meter to cut off power to the house subpanel which is not a typical feature of temp power panel.

I'm not sure what you're after there. When you cut the main breaker in the Ranch Panel, it'll cut power to everything - both the house and the auxiliary loads (RV outlet, GFCI etc.) at the ranch panel. Are you saying you want to keep those auxiliary loads live when you cut the house? If so, you will need to come off the feed-thru lugs and go to another disconnect below it. Or pick one of the few brands of panel that offers a 200A branch circuit breaker, and use 4 of your 8 spaces for that breaker.