I have a junction box with a knockout that is 1-5/8" diameter. (it was homebrewed, possibly in 1929).

Would this be suggestive of a particular type of conduit? It will definitely be metal conduit.

Related, I need to make a sharp turn out of that, turning 90 degrees in about 5". Is there a way to do that? I do have access to one side, but it's rather awkward so I'd like to avoid a conduit body.

  • I guess if you shrank down to 1/2 or 3/4 EMT I see manufactured sweeps with a 4 or 4.5 inch radius, though by the time you get a straight section to insert in the fitting you might have lost it on making 5 inches. I don't recall what the radius on my bender is, and it's miles away.
    – Ecnerwal
    May 29, 2019 at 1:24

2 Answers 2


1-1/4" pipe (which are also IMC/RMC sizes) are 1.660 OD which is pretty close to 1.625. The thread start diameter on the narrow end of pipe threads is 1.557 so a nipple ought to get in the hole even if it's just that size. EMT fittings (on the threaded part) are normally threaded the same as the pipe/RMC/IMC size.

One of those weird pulling elbows is the only sharp turn I know of in conduit, other than using a conduit body, or a box.

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  • I won't be able to get to that side of it. The best I can hope for is to use an LR conduit body, but that will be awkward. May 28, 2019 at 23:28
  • Would a pull box help ? And they make a fitting were you can make what you need. LB LR Seen them never used one yet.
    – user101687
    May 29, 2019 at 0:16
  • Not sure about your question ..If fittings, as in the male. Not working to box the do have washers to reduce whole size to hold fitting . Or if you want to reduce conduit down.
    – user101687
    May 29, 2019 at 0:23

1-1/4" conduit requires a 1-3/4" knock-out hole, so I'm guessing that's what you have, because the next size down is 1" conduit, which is a 1-3/8" hole, so a lot smaller.

That will not dictate the TYPE of conduit, it's just the standard hole size for what is referred to as 1-1/4" because even if it is EMT, the fittings for it still use the same threads as RGC or IMC.

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