Be aware you may be automatically signing up one of your services for commercial rate billing. (Standard practice here with more meters than legal dwelling units.)

Also be aware that generator backup (specifically an ATS) is made more difficult with the split service/metering.

My code is CEC, so can't help you much there.

 

I'm actually replacing my existing two meters with one. My second meter is currently incurring a monthly base fee (and electricity is charged at commercial rates)...which is one of the reasons I'm doing all of this in the first place. It's how the house was setup when I bought it...

 

400A residential service is quite common. Honestly, though, I'd go with one of those 400A meter-mains that has one of the 200A breakers feed an 8-space panel and thru-lugs, then come off the thru-lugs to feed the garage. 200A is a staggering amount of power for a garage - I have a former factory building with less power than that! And those 8 spaces will let you siphon off some of that surplus in case your home's needs exceed 200A - which can certainly happen in an all-electric home, especially if you ever go heat-pump (think emergency heat) or on-demand hot water.

I'm OK with 200A on 4/0, but a little troubled by how you got to it. Table 310.15(B)(16) only grants 180A to 4/0 wire (75C column, since your terminations are 75C). You'd have to rely on the "round up for feeders" rule 240.4(B) or the "83% for entire service" rule 310.15(B)(7). The entire-service rule allows for taps, but I'm not sure this qualifies.

Since you're running conduit all the way to the garage, why MF? Why not just individual THWN/XHHW wires? MH binds the wires together, which makes them a great deal more stiff and a PITA to pull. Remember you're not allowed to assemble the conduit around the wires, you must completely finish the conduit then pull the wires.

I don't believe Al wire is permissible for a grounding electrode. Not least, inline splices are not allowed in grounding electrodes, so you can't splice Al to Cu in a non-corrosive location. That leaves you forced to attach Al wire to water pipe: the electrode strap would have to be rated for Al wire, and I don't see how you'd contain galvanic corrosion.

 

400A residential service is quite common. Honestly, though, I'd go with one of those 400A meter-mains that has one of the 200A breakers feed an 8-space panel and thru-lugs, then come off the thru-lugs to feed the garage. 200A is a staggering amount of power for a garage - I have a former factory building with less power than that! And those 8 spaces will let you siphon off some of that surplus in case your home's needs exceed 200A - which can certainly happen in an all-electric home, especially if you ever go heat-pump (think emergency heat) or on-demand hot water.

I'm OK with 200A on 4/0, but a little troubled by how you got to it. Table 310.15(B)(16) only grants 180A to 4/0 wire (75C column, since your terminations are 75C). You'd have to rely on the "round up for feeders" rule 240.4(B) or the "83% for entire service" rule 310.15(B)(7). The entire-service rule allows for taps, but I'm not sure this qualifies.

Since you're running conduit all the way to the garage, why MF? Why not just individual THWN/XHHW wires? MH binds the wires together, which makes them a great deal more stiff and a PITA to pull. Remember you're not allowed to assemble the conduit around the wires, you must completely finish the conduit then pull the wires.

I don't believe Al wire is permissible for a grounding electrode. Not least, inline splices are not allowed in grounding electrodes, so you can't splice Al to Cu in a non-corrosive location. That leaves you forced to attach Al wire to water pipe: the electrode strap would have to be rated for Al wire, and I don't see how you'd contain galvanic corrosion.

Thanks for the feedback.

I am indeed relying on 310.15(B)(7) to use 4/0 for the 200A feeder...I should update my notes. And because of that, I can't really use a meter-main combo (like the 8-space you mentioned above) - if I pull anything in the house from anywhere except the 200A panel inside...then I can no longer use 310.15(B)(7) because the entire dwelling is no longer solely serviced from the 200A feeder.

I need a disconnect outside for the house anyhow...given I've got a 40ft run in the crawlspace to reach the panel. Which is why I was going with the meter-main combo with two 200-amp breakers built-in. I don't technically need a disconnect for the garage (I think) so I could get away with running the house off one 200A breaker and run the garage on the pass-thru lugs...but I like having a remote disconnect to completely de-energize the garage. I understand that 200A is a lot for a garage but I've already got a hot tub, welder, attic fan, air compressor, power tools, etc on that feed and I'm assuming I'll likely have one or two EV chargers on there within the next decade. I'd rather do this one time and not have to re-do it in 10 years.

Good to know about the Al for the water pipe connection...makes sense...I will plan to use copper for that.

I was on the fence about using XHHW in conduit to the garage and if it'll be easier to pull I'll likely just go that route then. I'm still not sure if there's any practical way around running XHHW in conduit in the crawlspace from the meter to the panel.