Direct bury electric

[Bill M]

I'm going to put some direct bury wire in piggybacking a waterline. I likely will run about 100 ft. Will 12-2 work for that distance. Very low energy things will be run on it. Thanks.

[Todd-ty729]

Yes it will give you power at that distance but that is borderline depending on what is being used.

Voltage drop is a factor.

Low voltage is a relative term. If there is anything like a refrigerator or freezer that has a compressor on it the initial start up of the unit creates a voltage hit that can be an issue for the appliance.

I would suggest running it in a conduit even though it is direct bury and also possibly going to a 10 gauge wire just for a little extra. Maybe even 10-3 with a ground in case you want to separate circuits.

Conduit helps keep the wire cool and the larger size helps with voltage drop.

[dallred]

I also recommend conduit. We had direct burial cable at a place we had in Winnsboro and gophers chewed through it. Pay now or possible pay more later. Good luck.

[D4H]

As others have stated, 10/3 in conduit but run it in larger conduit to allow for a larger wire size if needed later.

[Mike D]

Bill I know it will same money up front but I third the recommendation to install conduit. If anything ever happens to that direct bury wire you will have to replace the entire run to do it correctly. With conduit at least you can pull out and in new wire.

100’ is a long way to push a 120/240 circuit. You are going to have voltage drop issues.


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[60 Deluxe]

I would just skip the direct burial and put THHN 10 ga. in conduit. It is pretty easy to do if you will lay your wire in the trench and slide each piece of conduit on and then glue it as you go.

[muzzlebrake]

In Conduit is mo better. Check voltage at the source. If you have 126-127 volts then you will be good to 100ft with a 12/2 solid copper with ground wire for a 120v 20amp circuit. If you only have 115v at the source then you will be low at 100 ft.

At my house all of my circuits at the panel show 127 volts but my service entrance is only 70ft from the XFMR. I have a 100ft total run to my shop on #12 solid Romex UF-B that still shows 125v in the shop. When my 5hp air compressor comes on it will flicker the shop lights but doesn't trip any breakers.

You might even want to consider 12/3 with ground wire just in case you ever want 240/1ph.
#12 for 20 amp
#10 for 30 amp
#8 for 40 amp

[silencer2011]

I worked for an electrical engineering company for about 16 years and I will tell you that I like anything in conduit better than anything not in conduit unless it's in cable tray. You can google a plethora of voltage drop calculators that will help you decide what wire size you need. Plug in the load and voltage of what you want to run and the distance you want it to run and it will tell you what percentage v-drop you will have. Our company operated on a 3% limit for voltage drop. Basically if we determined we were going to be at 115-116 vac then we upsized the wire, but we also had a really cool spreadsheet with all sorts of formulas that made life easier.

[Bill M]

Yes it will give you power at that distance but that is borderline depending on what is being used.

Voltage drop is a factor.

Low voltage is a relative term. If there is anything like a refrigerator or freezer that has a compressor on it the initial start up of the unit creates a voltage hit that can be an issue for the appliance.

I would suggest running it in a conduit even though it is direct bury and also possibly going to a 10 gauge wire just for a little extra. Maybe even 10-3 with a ground in case you want to separate circuits.

Conduit helps keep the wire cool and the larger size helps with voltage drop.

I also recommend conduit. We had direct burial cable at a place we had in Winnsboro and gophers chewed through it. Pay now or possible pay more later. Good luck.

As others have stated, 10/3 in conduit but run it in larger conduit to allow for a larger wire size if needed later.

Bill I know it will same money up front but I third the recommendation to install conduit. If anything ever happens to that direct bury wire you will have to replace the entire run to do it correctly. With conduit at least you can pull out and in new wire.

100’ is a long way to push a 120/240 circuit. You are going to have voltage drop issues.


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I would just skip the direct burial and put THHN 10 ga. in conduit. It is pretty easy to do if you will lay your wire in the trench and slide each piece of conduit on and then glue it as you go.

In Conduit is mo better. Check voltage at the source. If you have 126-127 volts then you will be good to 100ft with a 12/2 solid copper with ground wire for a 120v 20amp circuit. If you only have 115v at the source then you will be low at 100 ft.

At my house all of my circuits at the panel show 127 volts but my service entrance is only 70ft from the XFMR. I have a 100ft total run to my shop on #12 solid Romex UF-B that still shows 125v in the shop. When my 5hp air compressor comes on it will flicker the shop lights but doesn't trip any breakers.

You might even want to consider 12/3 with ground wire just in case you ever want 240/1ph.
#12 for 20 amp
#10 for 30 amp
#8 for 40 amp

I worked for an electrical engineering company for about 16 years and I will tell you that I like anything in conduit better than anything not in conduit unless it's in cable tray. You can google a plethora of voltage drop calculators that will help you decide what wire size you need. Plug in the load and voltage of what you want to run and the distance you want it to run and it will tell you what percentage v-drop you will have. Our company operated on a 3% limit for voltage drop. Basically if we determined we were going to be at 115-116 vac then we upsized the wire, but we also had a really cool spreadsheet with all sorts of formulas that made life easier.

Thanks everyone. I'm convinced and it also saves me from going to the expense at the moment. I don't need it right now and maybe not ever. It was a "ok, I have the ground open" thing. Appreciate it.

[Rubberdown]

Shoot I’d imagine the conduit is cheaper than the wire isn’t it? Drop that conduit in there while the ground is open. Cap both ends. Makes it easy later and it ain’t much money.

[db@100]

I would just skip the direct burial and put THHN 10 ga. in conduit. It is pretty easy to do if you will lay your wire in the trench and slide each piece of conduit on and then glue it as you go.

THIS.....use THHN not UF. Easier and cheaper.

[Greenheadless]

slide each piece of conduit on and then glue it as you go.

Or get you some string and a shop vac that can also blow. Then bundle your conductors and pull back thru

[Todd-ty729]

Put in conduit. You might want power later.

[Quackerbox]

Pull sing will sail right thru with eirlther some light foam on a balloon tied to one end. Shop vac or a compressor.



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[60 Deluxe]

Nice to know the shop vac trick now that I have no plans to ever put any wire in the ground. Thanks.