3

I’m installing a 240v 60a branch for a hardwired ChargePoint Home Flex, set to a 48a load.

I’m planning to use 6-3 THHN, with 8g ground in conduit. I’m looking for recommendations on the correct type of conduit to insure I’m code-compliant (NFPA 70 2020).

As for the branch circuit, the cable run is 18’ total, from the service panel up to the floor joists, with two 90° turns before going straight through a wall that is perpendicular to the box. This is the same wall that the EVPS will mount to inside the garage where the conduit emerges from the wall.

oadesign
  • 61
  • 5
  • 1
    Of course you know the bends must be either a) sweeps, or b) conduit bodies which must remain accessible at all times, right? Cannot assemble conduit over wires and cannot use plumbing elbows in any case. – Harper - Reinstate Monica Jul 06 '21 at 16:11

1 Answers1

5

If you use EMT (or IMC/RMC but they cost more and are harder to work with) you can skip the grounding conductor, as the metallic conduit serves the purpose.

3/4" EMT would be adequate size. 1" EMT would let you use 4 AWG aluminum, which is about half the price of 6 AWG copper for the same ampacity. Perhaps not that big of a deal for an 18 foot run, but it still might be a win overall. For 6AWG you have to buy the appropriate colors - for 4 AWG you can buy all black (and that's often the only choice) and mark the ends of the wires to indicate which is the neutral (i.e. wrap with white tape or heat-shrink tubing.)

3/4" FMC (flexible metallic conduit) does need the grounding conductor, but is flexible and provides meaningful protection from rodent teeth for the 6-6-6-8. You'd need 1" for a 4-4-4-8 (copper ground, remainder aluminum) arrangement.

  • 1" ENT ("smurf tube") would work for a plastic product and the 6-6-6-8 or 4-4-4-8 configuration. (since it appears that the run is not "exposed to damage")
  • PVC-40 (since it appears that the run is not "exposed to damage") would also work - 3/4" for 6-6-6-8, 1" for 4-4-4-8.
  • 1" and 1-1/4" respectively if using PVC-80.

There are others, but that's a number of the usual options.

If the run is "exposed to damage" one of the metal options or PVC-80 are needed in the parts where it's vulnerable. Your description of the run does not appear to involve any parts meeting that definition.

Ecnerwal
  • 213,340
  • 10
  • 261
  • 571
  • 1
    Smurf tube has similar requirements as schedule 40 as far as protection, it’s easy to run compared to other methods . I fully agree. – Ed Beal Jul 06 '21 at 13:57
  • Everybody but me loves flexible conduit. I find when pulling, much of the pulling/pushing force moves the conduit instead of the wire. Only when the conduit is strained to the limits of its travel will force start to move the wire. So it makes the force greater in an annoying way. – Harper - Reinstate Monica Jul 06 '21 at 16:13
  • I hate LFNC (and did not suggest it) as the worst thing I've ever had to pull through. For 18 feet of not very complex geometry by the description, I doubt either of the flex options mentioned will be awful, but I did lead with EMT, which I prefer - but that's harder for someone new to it and unequipped (no bender) to manage. Heck, I'd need a new bender to do 1", for that matter. – Ecnerwal Jul 06 '21 at 16:41
  • Thanks everyone! I'd been considering 1" (blue) smurf, but wanted to make sure that I was code-compliant. It's not a very complex run, and is a straight shot through the wall into the garage. – oadesign Jul 06 '21 at 18:50