In Washington state is it ok to install a septic drain field over electrical lines in a sealed conduit buried 3ft deep?

I have not done it but looking for locations on my property and wondering if it's ok or smart to do. Did not find anything on the web. Thanks Dean

  • 1
    Isn't your drain field going to be more than 3 feet deep?
    – Mark
    Commented Jan 21 at 6:33
  • Sounds like a lot of hand digging. As far as the NEC, I think you're fine. NEC Table 300.5 has burial depth special cases that don't even hint at yours, so I expect that the catchall applies. Around septic could be a corrosive environment, so you might look at the pools special-equipment section for the "smart to do" component of your question. My recollection is that PVC, RMC, and IMC are okay for corrosive areas associated with pool chemicals.
    – popham
    Commented Jan 21 at 6:53
  • Mark - In my reading it says they can be anywhere from 18in to 3ft deep. But I just had a thought while typing this. Maybe the key would be to have the trenches for the drain field pipes spaced to skip the power trench. I don't recall what the spacing requirements are, but i am sure there is a range and depending on design. That would be a perfect solution. This power 200 amp power feeds a panel with 50 amp for RV sub panel on same post, so not for house. House power would be pulled in different trench when or if that happens. But thanks for getting me to think it though more...lol
    – Dean
    Commented Jan 22 at 4:14

1 Answer 1


Nothing addresses drain fields in RCW 19.28 (laws) or WAC 296-46B (124 pages of changes to the NEC because state bureaucrats know more than the NFPA). Your local county or city may have adopted additional codes that modify the NEC further.

Just FWIW glued electrical PVC doesn't normally produce a seal. In WA if you pull wire out of a conduit for replacement or salvage the wire will be wet more often than not.

  • If exterior/underground conduit is perfectly sealed, wire will be wet almost everywhere, (perhaps not some desert areas) simply from condensation collecting in the conduit.
    – Ecnerwal
    Commented Jan 21 at 15:02
  • This answer would be better without the unsupported rant.
    – isherwood
    Commented Jan 21 at 15:45

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