what is the difference between plumbing pipe threads and conduit threads?

Answer 1

plumbing and conduit are threaded with the same type of pipe threader, on a 3/4" per foot taper. I own the older type of threader, where you have to do all the threading by hand, but they make a threading machine that takes alot of the old cranking out of hand-threading field- cut pipe.
Conduit and plumbing pipe made in the factory are threaded to the same specs. I'm a heating and air conditioning mechanic, used to doing work in plumbing and electrical simultaneously- and i have been known to use the occasional 1/2" or 3/4" plumbing fitting to join two electrical boxes together in the past.
The most common threading machine in the states is made by rigid, I have attached a link to their site

p.s. I didn't mean to cause a big stir by putting the word "taper" in the definition. The real truth- is that if you thread conduit- it tapers. You just can't see the taper as much because standard practice is to stop short of threading by one thread. Think about it- you put threads on the pipe by REMOVING material. Each turn of the cutting head going deeper into the pipe. REMOVING MATERIAL tapers the pipe.
Store bought compression couplings are not tapered- but they do this so that they work with straight-cut unthreaded pipe.

Secondly- you really shouldn't use plumbing fittings in electrical systems- the burs on steel pipe are much more difficult to remove than those on softer metal conduit- so it can nick wires.

Answer 2

This Site Might Help You.

RE:
what is the difference between plumbing pipe threads and conduit threads?

Answer 3

There is no difference in the threads on the pipe it's the fittings that are different. Couplings for electrical are straight threads and couplings for plumbing are tapered. The taper on the pipe thread is 3/4" per foot on both types of pipe. I'm a master electrician, so I do know what I'm talking about on this one.

Answer 4

Plumbing threads are cut on a taper so they will seal with the fittings to hold gas or water. Conduit threads are not cut on a taper. They are only to tighten the nut over the compression fitting.

Answer 5

Rigid Electric Pipe Threader

Answer 6

Threads are the same it is called NPT (national pipe thread) but the pipe is different as are the fittings do not mix them it will not pass code, using water pipe could cause wires to be nicked or cut causing shorts.

Answer 7

if it is a waste line and not a supply line, you could use what i've always know as a fernco coupling. these are those rubber couplings with the screw clamps on either end. you can then leave the pvc inside the cast iron and attach a new piece of pvc. I've also seen pvc removed with a dremmel attachment to grind the pvc away from the cast iron. the first option here is easier and you won't risk breaking your cast iron pipe which is brittle. However that coupling is not to be used under pressure, so if it is a supply line you can't use it. good luck with it.

Answer 8

Black Pipe Threader