Conduits

[PEinVA]

Does a 3" conduit typically have a 3" outer diameter?
Thanks.

RC
All that is necessary for the triumph of evil is that good men do nothing.
Edmund Burke

 

[mcgyvr]

rigid steel conduit (RSC)
3" trade size = 3.090" ID and 3.5" OD

 

[PEinVA]

Ok, just wanted to confirm that.

SCH. 40 pipes that we use structurally are same way.
Thanks.


RC
All that is necessary for the triumph of evil is that good men do nothing.
Edmund Burke

 

[waross]

My understanding is that rigid conduit starts life as schedule 40 black iron. The approval standards include removing any internal welding flash. Conduit is galvanized externally and may be galvanized or epoxy coated internally.
The same dies are used to thread conduit as are used for schedule 40 structural or piping. The couplings are different and may be marked EC.

Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[BJC]

"My understanding is that rigid conduit starts life as schedule 40 black iron"
Only the size is the same. Conduit is made from lower grade of metal. Pot metal, old tin cans, fords etc) and is seamed. I have seen a person who tried to make a temporary air filter out conduit and some sanitary napkins. The pipe opened along the seam like a zip lock bag.
IT 's also very hard to bend black iron pipe in 3/4" and 1" size with a hickey. Be very respectiful of someone who can.

 

[waross]

Hi BJC;
Do you remember when the characteristic of rigid conduit went from very soft but not uniformly so to very hard? The new conduit rendered "One-Shot" hydraulic benders obsolete almost overnight.

Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[BJC]

Don't remember it yet. doesn't seem to have happened here yet. I can still buy a one-shot.

 

[waross]

There was a time when conduit went from very soft to very hard. It was so hard that the conduit would leave the center of the one shot bender and kink. Most of the contractors changed to roll-up type benders. I'm glad to hear that not all areas were affected.
ps: We can still buy One-Shots, but we can't bend most conduit with them. They are great for aluminum rigid conduit. Actually, I haven't tried for years. Not much call for rigid conduit bending skills anymore.

Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[BJC]

Are you thinking of IMC? Intermeiate metal conduit had a wall thickness between GRS and EMT. Metal quality did affect bending. The reduced cost of material didn't offset the trouble a lot of people had with it. I think that was the reason it didn't become very popular.
We use it on long straight runs because it's easy and lighter. When we get down to termination points where you have make some bends or offsets we switch to rigid.

 

[waross]

In our area we didn't see IMC. Our vocational school sent back about 10,000 feet of rigid steel conduit that had been purchased to teach apprentice electricians pipe bending skills. The new pipe would not bend properly in a one shot bender. Soon the only conduit available was the super hard unbendable stuff. Now our contractors use roll-up, formed shoe benders. I haven't seen a new "One Shot" for years.

Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[BJC]

Page 123 of the attached. We buy them ever so often.

http://www.greenlee.com/cat_docs/Bending08_lowrez.pdf

 

[waross]

Yes, we're on the same page. (grin) That's what I know as a one shot. With the super hard conduit the conduit would leave the center of the shoe and kink. The old one-shots are still used for segment bending and (with special shoes) for bus bar bending.
I'm glad to hear that softer conduit is still available somewhere. BTW, 1 inch seemed to be the worst for kinking.

Bill
--------------------
"Why not the best?"
Jimmy Carter