depth to bury electrical conduit

[randy41]

i was reading on the web somewhere that the required depth for pvc conduit is 18" and the required depth for rigid metal conduit is 6". is rigid metal conduit the same as EMT? do these depths sound right?
i am burying a wire from my workshop building to my high tunnel...about 60'. this is to run an inflation blower and ventilation fans.

 

[Egon]

Check your local CODE'S. :thumbsup:

 

[JerryK]

i was reading on the web somewhere that the required depth for pvc conduit is 18" and the required depth for rigid metal conduit is 6". is rigid metal conduit the same as EMT? do these depths sound right?
i am burying a wire from my workshop building to my high tunnel...about 60'. this is to run an inflation blower and ventilation fans.

EMT is thinwall...has slip on conectors..NOT liquid tight. Rigid pipe is threaded pipe...and in practice is not always liquid tite unless installed right. Electrical PVC conduit [ the grey stuff ] is not very expensive, sometime cheap enough to add another conduit to the trench for future stuff [phone, alarm, Cable for T.V., etc. ], and most places want you to bury it at least 24" under the ground. You should check your local code. Wire buried at any depth is not idiot proof. I have hand dug many trenches. Remove the sod with a square shovel and set aside. Dig down a shovel depth with the square shovel, then dig the final depth with a long handled long bladed trench shovel. [ the long skinney funny looking shovels they sell at Home Depot/Lowes/etc. ] Good luck, Jerry.

 

[randy41]

i just read the local code (which is the VA code) and it calls for 18" for pvc conduit. however it also states that if the cable is a residential branch circuit rated 120v or less with gfci protection and maximum overcurrent protection of 20 amps the depth is 12". i may make a run at it with the middle buster and then clean out the ditch by hand.

 

[beppington]

For the run from my power co's transformer to my disconnect panel, my power co required me to bury a 2.5" conduit 36" deep

I used a 4" trenching shovel - Now that was one deep slot!

 

[JerryK]

i just read the local code (which is the VA code) and it calls for 18" for pvc conduit. however it also states that if the cable is a residential branch circuit rated 120v or less with gfci protection and maximum overcurrent protection of 20 amps the depth is 12". i may make a run at it with the middle buster and then clean out the ditch by hand.

When you go to buy your PVC pipe, again, consider how cheap it is and take a minute to ponder adding another run of conduit...... Also, try to think of reasons not to run anything less than 1"... Check the price differences between the different sizes real hard.... Just my 2 cents.....

 

[randy41]

i agree with you about that jerry after all the times i had to go back and do things over for not planning ahead.

 

[Tractor Seabee]

18", for any type conduit or direct burial, is the minimum in most code enforcing jurisdictions. The advice about 1" min and an extra conduit is sound. Get some marker tape and bury 6" above so that gets drug up first at some later date. Rigid steel is very seldom used any more due to both material and labor cost. If you want to make it real idiot proof encase in concrete. Make sure the wire you buy is THWN/THHN or USE. Direct bury cable (cheapest way to go) must be USE rated. I am starting a project to feed future out-buildings before before I pour a concrete driveway. I am putting in 2- 2" conduits and seperate pull boxes, one for power and the other for signal circuits. Sure do not want to cut up that concrete later. Doing the same with water and sewer. PLAN AHEAD!!

Ron

 

[20 20]

I buried mine anywhere from 30 to 36" incehs deep, the inspector said I was above and beyond codes. I did some of it by hand{90+feet} he said I was nutz:laughing:

 

[valley]

If you not having it inspected, on you own property you'll know where it is. Put it in PVC it's water proof, lay boards on top of that if you think you need to. Some places are not that easy to dig don't know about your place. I've laid water proof armored cable with romax to the barn here.

 

[randy41]

the job is complete. the depth of the ditch is anywhere from 12-18". i put 2 1 1/4" grey pvc lines in one of which contains my 12/2 w ground UF cable. the other is awaiting the future need. i also put a 3/4" white pvc line in the ditch for water. not sure if i'm going to use it. i dug the 60' ditch by hand over several days. still backfilling (by hand) and i'll put a warning tape along the run above the pipes after they are covered by a few inches of dirt.
in my workshop building i ran the uf cable to a junction box and then hooked up to nmb cable to run to the breaker box.
sticker shock at the cost of 100' uf cable. it was just about half the cost.

 

[JerryK]

Some day you will pat yourself on the back for thinking ahead... when you run your T.V. cable out there, the internet cable, the phone line, the alarm system wires, etc..

 

[wrooster]

the job is complete. the depth of the ditch is anywhere from 12-18". i put 2 1 1/4" grey pvc lines in one of which contains my 12/2 w ground UF cable.

in my workshop building i ran the uf cable to a junction box and then hooked up to nmb cable to run to the breaker box.

sticker shock at the cost of 100' uf cable. it was just about half the cost.

1)
Per NEC and most local codes, minimum depth to the top of the conduit is 18".

2)
Running multi-conductor cable in conduit has to be approached with caution in several aspects, otherwise it is non-code compliant. Generally you pull individual THWN-rated wire through conduit, and only sleeve multi-conductor cable with conduit where necessary for physical protection.

3)
You can save a lot of money using individual THWN-rated wire compared to using UF cable.

Wrooster

 

[wrooster]

Put it in PVC it's water proof

You can use NASA-grade solvent glue for the joints and underground conduit will still fill with water. Ask any electrician if he has *ever* seen a bone dry underground conduit. The problem is condensation. The cooler-than-the-air surrounding soil causes condensation in the conduit, and it slowly fills with water. This is unavoidable.

For this reason, the NEC classes an underground raceway/conduit as a "wet" location, and the wire pulled through it has to be rated for use in a wet location -- e.g. THWN rated insulation (the "W" stands for "wet").

Wrooster

 

[grsthegreat]

1)
Per NEC and most local codes, minimum depth to the top of the conduit is 18".

2)
Running multi-conductor cable in conduit has to be approached with caution in several aspects, otherwise it is non-code compliant. Generally you pull individual THWN-rated wire through conduit, and only sleeve multi-conductor cable with conduit where necessary for physical protection.

3)
You can save a lot of money using individual THWN-rated wire compared to using UF cable.

Wrooster

agree 100%.. however since the job is done i probably wouldnt worry about it. it will last a long time, especially as its only a 20 amp service and is in conduit.
You could have saved alot of $$$ by using individual xhhw or thhn runs, but thats neither here not there as its completed.

good job using the future pipe. i did that and ended up using them to pull a 3 way for barn lights and internet/phone years later