220VAC line burial depth ?

[bcarwell]

I'm routing a 220VAC line (AWG 4, 100 amp service) underground from utility pole 125 feet to my shed for a welder with ground and neutral. I'm putting it in conduit.
Can anyone tell me how deep the conduit is supposed to be buried to be up to code ?
I live in Liberty Hill, Texas and all I've been able to find is that it is subject to the Internation Residential Code which I don't have access too. Guess I could call City Hall but I'm sure I'd waste a lot of time on hold and get the run around, and I'd like to do some diggin' tomorrow.
Isn't it supposed to be about 1 1/2 feet ?
Also, for bonus points, I started the dig today with my Kubota 7500 and a Middlebuster I bought today at Tractor Supply. But with my 3PH all the way down, the most I could dig down was about 8 inches. I looked at my 3PH linkages and all I could find is that there are two holes (a few inches apart) on each side link arm which connect to the lifting arms and that I apparently could get a little more vertical movement of the linkage arms with less leverage by picking the holes that are closer in to the tractor. But even if I do so, it doesn't look like I'd get that much more vertical movement out of the 3PH/Middlebuster.
Any tip on how to get the Middlebuster to go deeper ?
Thanks,

Bob

 

[AndyMA]

All the electrical trenches I dig around here (Conn & Mass) are 3 feet. 12" of sand is put in trench and pipe is laid on it. More sand and then marker tape before finishing burying it. The marker tape and sand on top of conduit are telltale signs to anyone digging that there is a buried conduit.

Andy

 

[jkpell]

I met with our power company yesterday and they are putting the underground in at a depth of 4'. Thats what they do here in GA.

 

[Raddad]

Michigan is 24"

 

[caver]

18" but my code book is 1990. Local code could be more strict.

 

[billbill1]

I have always thought 18" was the minimum but I'm not sure.

 

[dirtworksequip]

bcarwell, I would imagine codes vary from state to state,but I can give you this advice. Any electrical runs that I ever put in where done at 4' bury depth. The reason being at that depth it has less chance of you or someone else digging into it accidentally. Waterlines are at 3'. If there is a water break and a crew comes out to repair the line they should not have to worry about getting into the electric. Even on your own property if it were me I would go with the 4' burial depth. Over time you may forget all about that electric service and conduit you put in. (your mind on something else) At less than 4' you or someone else may dig into it accidentally. One of these days someone else will own your property and have no idea that there is a conduit just 18" under the ground. Decide they want to plant a tree and auger down 2 feet for the tree........... Why create a dangerous situation for yourself or someone else. Go with 4' and be safe. Just my thoughts on conduit burial depth.

 

[Inspector507]

Can anyone tell me how deep the conduit is supposed to be buried to be up to code ?

Bob

Codes vary from place to place, but the NEC requires 18" of cover if using PVC.

 

[Farwell]

Bob,
I like 18 inches for conduit and 24 inches for direct burial but this will vary according to your location. Check with your licensed electrician.
Suggestion, take photos of the trench for future reference and prior to digging make sure where any other utilities are located and have them marked by the utility companies even if you know where they are, this provides you some insurance in case you hit something that shouldn't be where you are digging.
David B

 

[Cliff_Johns]

Another thing you can do is bury yellow caution tape a foot higher than the wire itself. This way, when the next person starts to dig, they might see the tape before they part the cable.

Cliff

 

[kmdigital]

Bob,
I like 18 inches for conduit and 24 inches for direct burial but this will vary according to your location.
David B

I believe this is the correct depth according to the NEC. You can always go deeper if you want, but it means moving a lot more dirt, both on the way out and going back in. And it takes a lot longer for the dirt to settle in the trench the deeper you go, so it is your choice. Personally, I go around 2 to 2-1/2 feet with conduit, because it is easy to back fill and settles quickly. 3' isn't too bad, but 4' is moving an great deal of dirt, especially if you are in a sandy area where it tends to cave in easily.

 

[dqdave1]

Our area requires 4 foot deep for run from pole to house. It also requires RED tape to be placed one foot above conduit in trench for warning .

 

[Ford850]

42 - 48 " for main line from the road to the house or meter. 18" from there or from the house to an outbuilding.

 

[GreatWhitehunter]

I think you need to rethink your conductor size. A 100Amp service requires #3 copper and #2 aluminum. And after 100FT run you need to factor in voltage drop. As for burial depth I'd go with the NEC since it is the minimum. I'd go with #1 copper for the VD and if your going THHN you'll be good for 130A.The voltage means little to the burial depth. In case your wondering you'd need 2" schedule 40 pvc and you could run 5 #1's you won't be able to use 1-1/2 since you can only get three in there and you should not downsize the neutral. And you need a ground also (bonding conductor).

Matt T.

 

[GaryBDavis]

bcarwell,

If you can't get your middle buster to go down as far as you like, the nearest rental place for a Ditchwitch is Cat Trax on Hwy 29. You can get a 3700 (diesel, ride-on) set up for a 4" wide trench that can go down 24". I think a day's rental is around $160 with tax. It comes with a front blade so you can fill the trench back in. If you land is fairly rocky, they also have rock saws but thoese are more like $300 a day. They are nice folks to deal with.

As far as depth goes, I've never put in anything deeper than 24".