[wireman3736]

I'm an electrician and everyone says that electrical conduit threads are a straight thread, Our code says a 3/4" taper per ft which I have been told is the same as plumbing threads and that our electrical couplings are a straight thread, does any one know if plumbing threads are 3/4" taper.
thanks wireman

[letmetellu]

The threads made with pipe dies have always seemed to me to be the same as plumbing which are taperred threads. I do know that the fitting that you buy for electrical connectors and lock nuts don't seem to be as precise as plumping thread, but I just assumed that was a manafucturing problem.

[wireman3736]

I just asked this question on an electrical forum I spend alot of time on and the response was that the pipe threads are the same as plumbing but the fittings are straight. we don't have to be water tight, thanks

[letmetellu]

I knew that the conduit fittings were alway loose. But like you say they don't have to be water tight. Thanks for letting me know.

[wireman3736]

Originally Posted by letmetellu

I knew that the conduit fittings were alway loose. But like you say they don't have to be water tight. Thanks for letting me know.

Actually the fittings are suppose to be tight to continue a good ground,

[wireman3736]

Originally Posted by speedball1

Wireman/ Letmetellu

Wireman I'm just a plumber but your last post confused the heck outta me. You said, "Actually the fittings are suppose to be tight to continue a good ground,"
I've been around construction sites most of my life. I always thought the gray plastic,( which are not conductive) were threaded and the metal conduit, (that is conductive) were connected by couplings with screws that locked the coupling in place. Please forgive my ignorance and satisfy my curiosity. Regards, Tom

Let me tell u metal conduit comes in many forms, the plastic (pvc) pipe is normally glued, one metal type they call electrical metallic tubing (EMT) is not threaded but connected by either compression fittings or the set screw type that your familiar with, there's also ridged and Intermediate conduit(IMC), both of these are heavy wall galvanized similar to your galvanized pipe, ridged is the heavier of the two. They do make set screw and compression connectors for these but if your doing any explosion proof work the threading is the requirement although now a days there may be other fittings that are approved for this application. when we do mast services some times theres a need for over a 10' length which is the normal length so additional length is needed and having a threader is handy to have on the job site to take care of this situation although you can get the compression fitting for this but it seams like every time I need one my supplier has to order it. There also expensive for a 2". Emt is used more then ridged but there are allot of applications for ridged also, although not like there used to be, again mostly hazard areas and also areas subject to physical damage. As far as the grounding goes some may use the pipe as a grounding conductor so for this reason the pipe need to continue a low impedance back to it's source so to open any overcurrent device in time of a short to ground. Hope I didn't babble on too much,

Signed Just an electrician.