what type of connector should i use to go into an outdoor electrical box from a 1/2" threaded pipe coming out of the ground? There are two pipes coming out of the ground - The thread is on the outside of the pipe.

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2 Answers 2


Assuming you have two same height fixed in place 1/2" conduits sticking out of the ground and a junction box with the same size fittings?

You will need to extend both conduits, one with a standard coupling and nipple, the other with an Ericson 3-piece coupling and same length nipple. You may need to go to an electrical supply house to get machined fitting like I linked to, you may not have enough clearance to install the bulky cast versions typically available at retail locations. Consider using a square two-gang box, it would be easier to work with.

You will need to install both nipples into the box, attach the pieces of the Ericson to one side, double threaded part to the nipple. Attach a standard coupling to the other. Screw the box assembly to the non-Ericson side then tighten the Ericson.

It is best to install the large piece of the Ericson and yoke on the lower side of the joint, if you put the large piece and collar side onto nipple coming from the box then the large piece tries to fall into place getting in the way while threading the box onto the conduit.


if you have the box pictured the pipes (RMC: rigid metal conduit) thread into the box. The easy way is to install the box before installing at-least one of the conduits. you probably need a reduction adaptor reduce those 3/4" holes down to 1/2"

Well, it's too late for that so the solutions is to use a conduit union,

Extend one of the conduits with a conduit union and extend the other with a plain joiner and short conduit to the same length. open the union and thread the loose half onto the box, thread the box onto the plain conduit and then close the union.

  • 1
    The conduit shown by the OP looks like the heavier-duty "rigid; RMC" or "intermediate metal conduit; IMC"; EMT has such thin walls that it's not threaded, but uses clamp/compression fittings. If OP uses EMT outdoors, they will need to use "rain tight" fittings to keep connections waterproof.
    – Armand
    Jun 4, 2023 at 4:42
  • 1
    That size box is normally 1/2" threads. Of course 1/2" threads are physically about 3/4" because 1/2" is the size of the hole in the conduit or pipe.
    – Ecnerwal
    Jun 4, 2023 at 12:23

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