Direct burial of well wire?

[waterguy]

Here to direct bury it must be uf wire and 18".

 

[wrooster]

Out here it's against code, if that matters, to place cased wire (romex, etc) inside conduit. It has the be single strand, solid wire. I'm not sure why, but that's their rules.

^^^ This. (mostly)

Per the NEC, for underground conduit you pull individual wires, insulation type THHN/THWN (the "W" is for wet locations, which underground conduit is classified as). You can get this type of wire in HD or Lowes on a spool. Note that in most cases, conduit + individual strands of wire will be less than multi-conductor UF cable. Unless properly derated, you can not put multiconductor cable in conduit except when the conduit is used in short lengths for physical protection against damage.

Note that you generally pull stranded wire, not solid wire, through conduit. Solid wire does not pull easily, and any bends will cause problems. The THHN/THWN wire on the shelf at HD or Lowes will typically be stranded.

Note also that per the NEC,
UF direct buried: 24";
UF direct buried, 20A or less, protected by GFCI breaker: 18";
wire in non-metallic schedule 40 conduit: 18" to top of conduit.

The advantages of using conduit are many-fold: rodent protection, damage protection, ease of wire replacement, etc.

Wrooster

 

[Tractor Seabee]

Check that wire first, you never know what some DYI did in pure ignorance of this stuff. If it is not marked USE on the jacket it is not whether but when it will fail. Do not put in conduit unless you go at least 1"; if you have to pull it out some day it probably won't come. Cable like that takes a set in the bends and has a high friction factor compared to single conductor.

Ron

 

[TRR]

Unless properly derated, you can not put multiconductor cable in conduit except when the conduit is used in short lengths for physical protection against damage.

As stated in the quote, NEC allows the cable to be run in conduit if it is derated for temperature. (The sheathed cable runs hotter than single wires) But normally, single wires are run. I've used both direct burial and conduit and both single wires and sheathed cable. As for which I'd use, it depends on the application, but now-days I tend more towards using conduit with or without sheathed cable.

 

[slowzuki]

The stranded well wire is soft and doesn't have much abrasion resistance. We had some direct buried for a while as the original got damaged, we laid it 4" under a driveway because the trench was dug at -30 C. Backfilled with sand and flooded with water to freeze it. Worked ok but was replaced a couple of years after as it was damaged in the freeze thaw.

At my place I used proper direct burial rated wire to get to the well then the proper splice kit to connect to the stranded going down the well.

 

[bozowise]

No question, at about $25 worth of conduit for 110 feet use it. It also gives you the ability to fish extra wires out the area at a later date which is a great plus for future needs.

 

[MillWeld]

I would be more worried about voltage drop at 110 feet. How many amp circuit?

It's a 7 amp load but the complete run is much longer than 110 ft - that's the length I'm adding. With no load at the site I measure 128 VAC; with the 7 amp blower on I measure 120 VAC. That's a 6% drop - a lot more than the acceptable 2% drop but I use the blower maybe once a day for 5 minutes. It's a dedicated circuit - only the blower is on it. I'll use conduit and go for it.
Bob

 

[Cap-n-Cray]

If you run 12g wire with a 15AMP breaker you should have no problems. When voltage get down to 100V then the problems really begin. Go for it. :thumbsup:

I'll bet you run more than just a blower. Radio? It should all work.

 

[MillWeld]

I'll bet you run more than just a blower. Radio? It should all work.

You got me there - I do run a BatteryMinder but no radio. It would have to be a ghetto blaster to hear it over the sawmill and my hearing protectors. Good idea about the 15 A breaker. Thanks,
Bob

 

[grsthegreat]

Honestly the greatest expense with ANY buried wire is the cost of the trench. Conduit is cheap.

Redigging the trench in 5 years is expensive.

Moral of this story.....use conduit.

As far as what the NEC shows...? all i know is i have seen well drillers wire used direct bury all the time and its never an issue with the inspectors. They also run it stapled on the wall in the pump house not in any conduit and the inspectors have no issues with it.