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Trenching for 1" Non-Metallic Liquidtight Conduit Type LFNC-B with 18" cover (10-3 W/G UF wire installed, 240V with 30A breaker) to serve a well. Just bumped into LPG line crossing conduit's path at same 18" depth. What is code requirement here? Can I still bury conduit here and if so, how far away from the LPG line must it be?

Could concrete be used to safely separate the lines-if so, how?

Do not have an alternate route for the electric line that would not cross LPG line.

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    Mixing electricity and gas? What could possibly go wrong? ;-) Seriously, though, why do you want to pull direct-bury cable through conduit? You should check the NEC. You would typically pull individual THHN/THWN wires through the conduit, and if it's more than a 6' run you're probably required to use type LFNC-B conduit (suitable for wet/dry/oily/hazardous applications). But you wouldn't normally pull cable through it.
    – Craig Tullis
    Mar 1, 2015 at 22:28
  • The cable was less expensive than individual THWN wires to match. The question is: can I cross the LPG line at all and if so, what is safe and proper here?
    – Lucky
    Mar 1, 2015 at 23:46

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Here's a reference to a document published by Puget Sound Energy regarding minimum separation (both horizontal and vertical) for gas and electrical service, so you can cross them.

In general it looks like at least 6" vertical separation with conduit, or 12" if the electrical is direct-bury. I'd check local code.

http://pse.com/accountsandservices/Construction/Documents/3061.pdf

I had it in my head that pulling that cable through conduit didn't meet code, but I think I was wrong (with qualifications, maybe). The hardest thing about that cable inside conduit is going to be pulling the cable. You're pulling a lot of extra insulation and it won't go around corners easily, etc. I guess the 1" conduit will help with that a little.

But considering the cable you purchased, couldn't you skip the conduit and just bury the cable (with appropriate protection where it emerges from the ground)?

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  • Thanks. Pulled cable through above ground, no curves yet, made it easy. Replacing same cable that WAS db and shorted/damaged, hence conduit this time.
    – Lucky
    Mar 2, 2015 at 0:36
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FYI: The local propane company requires that I maintain a 12" vertical separation with my electric line, so it must dip to 32"+, supplying 12" of separation under the crossing LPG pipe; in No. Calif.

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