I asked this question elsewhere and have checked the IRC for an answer. The only thing I could find on crawlspaces was E3802.4 I don't want to have a conduit running around the outside corner of the house. So, I was thinking of coming out of a ranch panel from the pass-through legs, route the service cable under the house (in the crawlspace), then back out and up to an automatic transfer switch located on the adjacent wall. I'm using XHHW-2 SE cable. Can I do this?
The "ranch panel" (main breaker + 4-12 breaker spaces for outbuildings + thru lugs + sometimes meter pan) is actually your main disconnect. Therefore we need to be clear:
- From weatherhead to meter pan is service entrance wire
- From meter pan to main breaker (ranch panel) is still service entrance wire (although it's a good idea to ground the meter pan; I do that with metal conduit between meter and main, super simple).
- From main breaker to anything else is feeder
Service wires are 3-wire cable such as SEU. They do not contain a ground wire.
Feeders are 4-wire cable such as SER, MH for outdoor runs, etc. The feeder must have a separate neutral and ground.
If your plan is to use 2-wire+wraparound neutral SEU service cable for the feeder from meter-main to anywhere else, no, that's not safe and will fail inspection. John Ward has a great video on why it's a terrible awful very bad nogood idea to combine neutral and safety ground anywhere past where the ground rods tie in. We used to allow it to dryers (banned in 1996) and subpanels (banned in 2008) but John's scenario just kept happening. In Europe you don't have a choice about this setup, but you do here, so take it.
The only useful use of SEU in modern times is for service wires, or single-voltage (120V, or 240V without neutral) feeders or branch lines, like you might have to a wellhouse or EV charging station.