Going to the Big Box Store

[Fulthrotl]

Electrical Rigid was always the straight thread, and the taper was for plumbing, the reason for the straight thread was so the lock nuts would tighten up, then the major manufactures decided they were loosing money on the two taper system, and changed the rules. Many of the younger guys never seen the stright thread system.

i'm 53, i have hair with a pretty good dose of gray in it, i've been playing
sparkie since 1977. before that, i worked in the machine tool industry as
both a machinist, and a q.c. inspector. before that, i was given a 6"
swing west bend lathe for my 7th birthday, by my father. i have a family
tree infested with machinists and toolmakers since the 1880's. i could read
micrometers before i could do fractions, and both my father and uncle
made their living in the oil tool business, which has a great deal to do
with threading pipe, up to 16" npt.

i have yet to see a npt thread that does not have a taper.

how far back are we talking about here?

NPT pipe threads - dimensions according ANSI/ASME B1.20.1:

NPT - National Pipe Thread Taper
Characteristics of NPT
(also known as ANSI/ASME B1.20.1 Pipe Threads, General Purpose):
tapered thread 1o 47'
The taper is 1/16 inch in an inch, which is the same as 3/4 inch
in a foot (angle 1o 47')

forgive me for being an anal POS here, but ALL pipe threads have the
SAME taper, there are NO STRAIGHT CUT PIPE THREADS WITH A NPT
DESIGNATION.

additionally, the couplings are cut with the SAME thread pitch as the
end of the pipe. the ONLY difference between electrical rigid, and pressure
rated plumbing pipe is HOW THE DIES ARE SET UP TO CUT THE PIPE.

honest. i wouldn't lie about it.....

randy

 

[Fulthrotl]

i have yet to see a npt thread that does not have a taper.

however, there IS a pipe threading standard called NPS,
which stands for National Pipe Straight.

the two thread styles are NOT interchangeable, and i have
never seen pipe commercially sold with NPS threads.

 

[ITO]

For a topic to go so far off, and blather on and on about plumbing and not be locked by the mods, this has been one great read.

Seriously?

...
sloppy and loose = sparky
tight and right = sprinkie

hope this helps.

Yes it did, its pure gold. I actually going to take notes for the next time some idiot engineer in an effort to prove how smart he is questions my methods.

 

[tkb]

Electrical Rigid was always the straight thread, and the taper was for plumbing, the reason for the straight thread was so the lock nuts would tighten up, then the major manufactures decided they were loosing money on the two taper system, and changed the rules. Many of the younger guys never seen the stright thread system.

I have never seen a straight thread on rigid pipe and I am not one of the younger guys.

I have been running rigid since 1972. The stone age. :grin:
How far back are you talking about?

 

[outside71]

Network

Network

Talk with some other electrical contractors that have the equipment and have one of their shop guys cut/thread/bend some pieces for you.
I worked for a small shop that did allot of industrial work and they did little jobs like this for other contractors.
You can also use threadless rigid fittings.

 

[mlp425]

Electrical conduit and plumbing pipe are the same thread NPT.

It's just another one of the myths about electrical.

I agree. Check out this .PDF http://www.steelconduit.org/pdf/ConGuide.pdf 4.1 Conduit Cutting and Threading
Guidelines (page #7)

 

[tkb]

I agree. Check out this .PDF http://www.steelconduit.org/pdf/ConGuide.pdf 4.1 Conduit Cutting and Threading
Guidelines (page #7)

Nice info. I saved it for future reference.

 

[Rockyd]

Thanks for the link MLP425!

As a special note to all the nay sayers of pipe dope, see page 24 in the link, my favorite brand per 110.3(B) in addition to 300.6(B) call out.

???First picture on page 1 is a violation of 314.28(A)(2)????Grrrr. They do pipe, not wire, still doesn't make it right. No wires were hurt in the filming of this production.

 

[Sparky555]

I don't know anything about pipe threading but when I tighten two sticks of IMC together with a coupler, the conduit butts together inside the coupler (definitely not gas or water-tight). Typically with gas or water pipe the pipe tightens before they butt together, leaving a space between the pipes. Either the threads are different or the couplings are different.

 

[tkb]

I don't know anything about pipe threading but when I tighten two sticks of IMC together with a coupler, the conduit butts together inside the coupler (definitely not gas or water-tight). Typically with gas or water pipe the pipe tightens before they butt together, leaving a space between the pipes. Either the threads are different or the couplings are different.

The couplings are different. The plumbing couplings have a tapered thread on both ends of the coupling and the electrical couplings are threaded straight through.

If you thread your electrical pipe too long the pipes will butt in the coupling.
If you threaded the electrical pipe longer than the coupling (a running thread and a code violation) you would be able to screw the electrical coupling on all the way. A plumbing coupling should only go on half way since it has tapered threads.

 

[mlnk]

Electrical is not tapered, and plumbing is tapered. If you need proof, check it out at the supply house. I beleive, about 10 years ago the Code started accepting either one for electrical.