Underground Wire terminology - what am I needing?

[PoPoShoo]

Will be running underground rated wire from Grid tie Inverter to main distribution box. We'd need a 4-strand (2 loads, 1 neutral and 1 ground).
What is this wire called?

Also, could the ground wire be of a thinner gauge then the 240v wiring? If so, we'd need a 3-strand wire and run seperate, smaller guage ground

 

[sunshine_eggo]

"direct bury"

You may find standard wire in conduit is cheaper.

Southwire 50 ft. 6/3 Gray Stranded CU UF-B W/G Wire 14782722 - The Home Depot

Southwire's copper UF-B cable is used in applications that include outside lamp posts, pumps and other loads. It can also be used for outbuildings such as garages and barns. UF-B feeds from a distribution

www.homedepot.com

 

[BentleyJ]

There are a number of good online sources for cut-to-length wire, a quick search should work. Regarding a smaller ground wire, the NEC does allow this and there are charts you can refer to to find permissible sizes but this generally done when pulling individual wires through conduit. Since you are going direct burial I would just go with a standard 4 conductor cable that is ready to go with everything inside the protective jacket.

 

[BobR]

Will be running underground rated wire from Grid tie Inverter to main distribution box. We'd need a 4-strand (2 loads, 1 neutral and 1 ground).
What is this wire called?

Also, could the ground wire be of a thinner gauge then the 240v wiring? If so, we'd need a 3-strand wire and run seperate, smaller guage ground

This is a direct bury wire I used to connect a sub panel in an out building. The neutral can be smaller because it is a 240/120 panel. https://www.wireandcableyourway.com/2-2-4-6-aluminum-mobile-home-feeder-cable

 

[justgary]

If you have a tractor available, you can pull your wire or conduit directly underground using a modified subsoiler blade. I pulled 120 feet of 1-1/4" conduit 20" underground with my small Kubota. A few passes with the blade alone to cut tree roots, then hook up the conduit and pull it in one stick.

I assembled the conduit with the wires and a spare pull cord inside before I pulled it underground.

It only took a few hours to pull 120' plus 80' of conduit 20" deep, then several hundred feet of water pipe 6" deep.

 

[John Frum]

URD Cable (Direct Burial) | WireAndCableYourWay.com

URD is used for underground secondary distribution and service entrance applications at 600 volts or less. Shop duplex, triplex, quadruplex & single conductor.

www.wireandcableyourway.com

 

[Supervstech]

If you are shopping various sources for romex style direct burial cable, use the search term UF cable, and the awg size needed for the conductors.
So, for a 30A cable, you would want UF 10-3w ground.

 

[NoWayMan]

If you have a tractor available, you can pull your wire or conduit directly underground using a modified subsoiler blade. I pulled 120 feet of 1-1/4" conduit 20" underground with my small Kubota. A few passes with the blade alone to cut tree roots, then hook up the conduit and pull it in one stick.

I assembled the conduit with the wires and a spare pull cord inside before I pulled it underground.

It only took a few hours to pull 120' plus 80' of conduit 20" deep, then several hundred feet of water pipe 6" deep.

Quick question on the conduit you pulled - was it a flexible type like Southwire makes, or did you pre-glue together rigid 10' sections? I'm considering an approach like this, but need a run with a 'bend' in it, and would like to use flexible conduit. Thanks!

 

[justgary]

Quick question on the conduit you pulled - was it a flexible type like Southwire makes, or did you pre-glue together rigid 10' sections? I'm considering an approach like this, but need a run with a 'bend' in it, and would like to use flexible conduit. Thanks!

I glued up the sticks of PVC conduit, let them rest a bit, then pulled them in. PVC will flex, so you don't have to run a straight line. The conduit took the bend at the rear of the trailer just fine.



The blade is essentially a modified subsoiler. It has an extra foot at the bottom to insert the conduit and cross pin it. This photo shows the foot at the top of the blade for transport. It is easy to unbolt the blade and flip it foot down when onsite. You do have to trench a bit at the start and finish in order to get a consistent depth.



The dowel inside the foot helps keep from crushing the conduit when turning or lifting the foot, and the screw in the end is to attach the pull rope so I didn't lose it.

 

[NoWayMan]

That is super helpful, thanks for posting the pictures @justgary !