Underground Conduit - 360 Rule

995 Views 8 Replies 4 Participants Last post by mikeyp78, Dec 30, 2019

mikeyp78

Discussion Starter · Dec 29, 2019

I'm helping a friend put in shed and he's running electric from the main panel in the house to a subpanel in the shed (it's more of a garage than a shed, but whatever). He's got all the required permits from the municipality, but the subcode official mentioned the 360 Rule (code) for the PVC conduit.

As I/we understand it to be (and here is where I need you folks to pipe in if I'm wrong or correct), no run of conduit can have more than a total of 360 degrees of turns or sweeps. To get around this number, we can put in condulet boxes in the run to assist with the wire pulls. In other words, if the total run is 150 feet, and it zigs and zags through the yard, we would need to put in a condulet box after every 360 degrees worth of turns along the line, and that would be satisfactory to pass the 360 Rule.

Hope that makes sense.

Cheers!

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surferdude2

· #4 · Dec 29, 2019 (Edited)

Consider using NM pull boxes where needed... keep them where they won't be driven over.

NM Pull Box Example

ps. That was kind of the inspector to inform you of the 360° rule. With a 150' u/g run, you'd be hard pressed to get a fish tape through 270° of turns, let alone 360°. Sometimes it's a challenge just to get up the last 90° riser an a long (over 100') 180° u/g. Depends on how new and straight the fish tape is and how many small jiggles there are in the u/g conduit.

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surferdude2

· #5 · Dec 29, 2019

One more thing... come into the pull box using a 45° bend to minimize the total bends in the run. Also be sure to use wet rated conductors such as thhn/thwn combo rated. Plain thhn isn't approved for wet applications, which all u/g's are considered to be.

SD2

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surferdude2

· #8 · Dec 30, 2019 (Edited)

Wiredindallas said:
A professional practice is to use a vacuum cleaner, string, and foam plug that matches the conduit size. You suck or blow the plug thru the conduit string attached. Beats the dickens out of a fish tape.

Amen... We finally migrated to using a leaf blower (sometimes an air compressor) for blowing a line through the conduits. Just tied a small piece of a plastic bag on the string for small conduits and a complete plastic bag for the larger runs. Worked a lot better than the vacuum... pulled 1/2" poly rope into 100' + runs.

SD2

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