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I have a 25’ run from an outdoor meter panel to a 200 amp home main breaker box, two phase. About 5’ of the run is through heavy conduit underground, into the basement. I have a lot of aluminum 4/0-4/0-4/0-2/0 SER to do the job.

I know I can't use the SER at least in the conduit. I believe that is due to heating in a confined conduit. My question is can I strip off the outer jacket and reinforcement in the underground conduit, thus separating the cables, and still meet code?

FreeMan
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electrical guy
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2 Answers2

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You can't use SER cable underground at all, conduit or not. See this previous question for details.

As far as stripping the cable sheath and using the individual wires. You can do that if and only if the wires are labelled such that they can be used that way. The biggest factor is that they must be rated for wet use, e.g., XHHW-2.

manassehkatz-Moving 2 Codidact
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  • Yea yea i know about SER U/G prohibition already. the individual wires are THWN and labeled as such. Its nit as good as xhhw but it does pass NEC. I guess my question is should i strip off the outer insulation through the entire run or just through the U/G conduit. – electrical guy Aug 15 '23 at 04:25
  • I don't think you have a choice. If you only strip the underground part then you'll have to split it between cable and wires. Which means crazy connectors between the two sections. So your choices are wires the whole way and add conduit to the outdoor section, or switch to underground rated cable for the whole run. – manassehkatz-Moving 2 Codidact Aug 15 '23 at 04:30
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    ok, good advice, ill strip off all the insulation and reinforcement theough the run. correction info, i actually looked at my reel and its southwire pn 13107808. Inner conductors are XHHW. – electrical guy Aug 15 '23 at 04:48
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Update edit. This is for a house i bought "as is". Currently the 200 amp main panel is being supplied by SEU 2/0-2/0-2/0-1/0 (00-00-00-0), the run is 5 ft u/g thru 2" pvc, through the crawl space and up to the main breaker box. No that is not a typo. Besides the obvious NEC violations, this is an actual fire hazard emergency and needs to be remedied immedately, as in today.

So I removed the old 2/0 SEU and replaced it with what I had on hand, 3x 4/0 conductors taken from the aforementioned SER cable, plus a marked 2/0 alum XHHW-2 wire for the ground. Unfortunately The 4/0's dont have any markings so I know it wont pass an inspection. On the other hand, I know all the conductors are correct size and XHHW-2 construction to meet the "spirit" of the code and prevent a fire. Its a stop gap measure until I can save up and buy copper 3x 3/0 THWN-2 and 1/0 ground.

ThreePhaseEel
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electrical guy
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