electricalwiring
Can I run 12-2 NM-B wire from my 20 amp dedicated breaker under my house and then using a four by four box splice 12-2 UF wire to run underground to my water pump house?
Running the wire would be in a dry crawl space, and the 4 x 4 box that the splice will be will also be in the dry crawl space mounted to a floor beam.
There are GFCI outlets that have indicator LEDs on them, like this one:
If you put this in the living space, then connect the sump receptacle (a normal, non-GFCI receptacle) to the "load" side of this outlet, it will also be protected. If it trips, the light will be out and you'll know it.
To make it more obvious, you could plug a nightlight into this outlet.
Even better, plug in an "emergency rechargeable flashlight": the kind that plug into the wall, but turn on automatically when you unplug them or the power goes out.
This would more readily draw attention: if the light is on, there is a problem.
Wiring in a crawl space (wet location) can be done successfully using a variety of means:
However, given the circumstances (i.e. the persistent wetness in the crawlspace), I'd be most comfortable with THWN in PVC and nonmetallic junction boxes down there, with the risers being THWN-in-PVC as well. The main downside, though, is that not only is this an expensive way to wire a house, most "wet location" electrical equipment will not survive being bathed in another storm surge!
The soffit proposal is elegant; however, the main problem is going to be providing access to junction boxes -- you'll need to have blank plates interrupting the molding (preferably on the bottom of the soffit) in order to provide access to junctions:
314.29 Boxes, Conduit Bodies, and Handhole Enclosures to Be Accessible. Boxes, conduit bodies, and handhole enclosures shall be installed so that the wiring contained in them can be rendered accessible without removing any part of the building or structure or, in underground circuits, without excavating sidewalks, paving, earth, or other substance that is to be used to establish the finished grade.
Further more, you'd have to use an "old work" type of junction box in this application as you wouldn't have framing members inside the soffit to attach the boxes to. While the 3" by 3" soffit interior should be adequate for cabling, I would not use a conduit inside it due to the soffit interfering with conduit body access. I do not know of any fire code requirement for horizontal cable chases other than them requiring firestopping when they penetrate a firewall; however, as mfarver pointed out, your AHJ has the final say on that, and internal firebreaks in the chase would be wise.
Another option for the soffit wiring case would be to use a plug-in, non-ventilated, totally enclosed busway system with branch circuit breakers at the outlet taps and type MC cable run exposed or NM run in surface raceways for the drops/horizontal runs to outlets and luminaires. While unusual for a residential application, plug-in busways offer a high degree of flexibility in layout, and can be subdivided so that branch circuits can be moved with only modest impacts on power to other parts of the house.
There are two drawbacks to this approach, other than it being relatively costly, though:
Best Answer
You can splice the NM above ground in a box above ground then run the UF to your pump. The depth for UF cable to be buried as you exit the foundation is 24” per NEC table 300.5.