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I'm installing a 220 volt 30 Amp plug for a scuba compressor.

I'm installing it my sun room. There is a hole in floor trim already from the old heating system so I was planning on using that. Run the wire from the panel and then into conduit once I reach the sunroom.

There are a few 90 degree turns one of which is only a couple inches so I'm trying to figure out what type of conduit to use.

I do not plan on using romenox.

Thanks for any insites enter image description here

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  • What is the name plate rating of the compressor?
    – JACK
    Nov 13, 2021 at 16:58
  • 4500 psi, 220volt single phase 18amp running amps
    – Newdiyer
    Nov 13, 2021 at 17:04
  • 2
    "romenox" = "romex" ?
    – brhans
    Nov 13, 2021 at 17:24
  • For :sharp bends in conduit, a pulling elbow or LB (LR, LL depending on the particular corner) serves as both a pulling access point and the ability to make a sharp corner (you cannot PULL around the sharp corner - you need to use the pulling access provided by the access cover on the fitting.)
    – Ecnerwal
    Nov 13, 2021 at 17:46
  • @Ecnerwal Good point, but the LB would still need to be permanently accessible . Nov 14, 2021 at 7:06

2 Answers 2

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If you are running individual wires (not cable), they'll need to be in conduit for the entire run. I personally like using non-metallic conduit because it's so easy to install vs. rigid or EMT. But always check with local codes. Also, using conduit that is somewhat larger than code requires makes pulling the wires much easier.

Also, you mentioned several 90 degree elbows. Code restricts the maximum degrees of curves to 360 degrees without a pull box. If you need more than that, you'll need to install a pull box somewhere in the run to divide the total number of degrees of curves to equal or less than 360. It must also be permanently accessible , not necessarily "readily accessible", just permanently.

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  • I plan on a pull box for both safety and ease.
    – Newdiyer
    Nov 13, 2021 at 16:33
  • I like EMT anywhere it's not going underground, but I learned to use a bender, which makes that easy. FMC is also a decent option if not into bending.
    – Ecnerwal
    Nov 13, 2021 at 17:43
  • Is there a way I can upload pictures?
    – Newdiyer
    Nov 13, 2021 at 18:08
  • Ok, photo of the problem corner added to original post.
    – Newdiyer
    Nov 13, 2021 at 20:10
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Generally, you use conduit one of two ways:

  • With a cable wiring method (e.g. Romex) that doesn't normally need conduit. You are just using it where you need an extra damage shield. In this case, it's "just a tube or channel" you slide over the cable and does not need to be certified as electrical conduit.

  • As a conduit wiring method to provide a path for wires that aren't allowed to run without conduit (e.g. THHN, XHHW, RHW, etc.) In this case you must use actual approved conduit such as EMT, not water pipe.

In the earlier case "damage shield", you must use cable rated for purpose such as Romex, but you can just slide sticks of conduit over the cable. This isn't really practical beyond about 1 stick.

Don't put the wires in!

In the latter case, "conduit as wiring method", you must assemble and mount the entire conduit run, complete, before adding any wires.

The above is a huge source of confusion for those who have used a stick of conduit in the past "as a damage shield" e.g. for an underground stub-up, or to protect a cable down to a light switch... but is now making the transition to proper conduit wiring.

"need to pull" implies certain things about construction. Obviously, it needs to be built pullable. That means every sharp corner needs an accessible cover so the pull can be broken up there. This creates a "pulling point" which must remain accessible without disassembling the building (not least so it can be found later!)

All other curves must be gentle "sweeps" and can be made inaccessible, however due to the practicality of pulling, there can be no more than 360 degrees (four 90s) of sweeps between pulling points (and a novice is better off aiming for "one 90, two at most".

Can wires exit conduit and run free?

Only if they are rated for doing so. For instance Romex cable can "just exit conduit anywhere" including at the end of a pipe, and run along rafters (if allowed).

However, THHN or XHHW wire must be in conduit its entire route.

That said, you don't need to stay in the same wiring method for the entire run. You can transition from one type to another at any junction box. I have a run at the lodge (not my work) that is EMT conduit/THHN up to a junction box, then Romex from that box, then down the basement wall in Romex in EMT conduit (strictly as a damage shield).

Cables rated for standalone use such as Romex are allowed inside conduit. However a) they are very stiff and difficult to pull, b) they take an inordinate amount of conduit fill since they behave as a round wire of the widest dimension (at extremes, 6/3 UF requires 2" conduit - really) and c) conduit is no help at using cables where they are not rated to go, e.g. "NM" Romex outdoors.

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  • Thanks, I'm using it just for added protection in the sun room. It appears I will use romex after all. Total amount of wire from box to plug should be about 40 feet.
    – Newdiyer
    Nov 14, 2021 at 16:06

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