Threading 1/2 Inch Or 3/4 Inch RMC Pipe - Electrical - Page 2 - DIY Chatroom Home Improvement Forum
Advertisement


Go Back   DIY Chatroom Home Improvement Forum > Home Improvement > Electrical

CLICK HERE AND JOIN OUR COMMUNITY TODAY...IT'S FREE!

Reply
 
Thread Tools
Display Modes
Old 12-31-2014, 11:02 PM   #16
Member
 
Join Date: Sep 2012
Posts: 10,233
Rewards Points: 1,466
Default


Quote:
Originally Posted by brric View Post
Straight what? plumbing threads and electrical conduit threads are BOTH NPT tapered threads.
I'm not the one to ask. Try the OP being he is the one that mentioned straight.
SeniorSitizen is online now   Reply With Quote
Sponsored Links
Advertisement
 
Old 01-01-2015, 04:33 AM   #17
Member
 
Join Date: Mar 2007
Location: Eighty Four, Pa.15330
Posts: 1,597
Rewards Points: 1,192
Default


Quote:
Originally Posted by brric View Post
Schedule 80 pvc can be threaded.
Thanks, but I'll just cut and glue. I thought I'd save a fitting.
bobelectric is offline   Reply With Quote
Sponsored Links
Advertisement
 
Old 01-01-2015, 09:45 AM   #18
Member
 
Join Date: Dec 2005
Location: Anchorage, Alaska
Posts: 244
Rewards Points: 220
Default


Quote:
Originally Posted by MT Stringer View Post
Do you think the guy would get tired of threading a ten foot piece if I asked for two three foot sections, and two two foot sections threaded on each end. :-)

Same goes for the next piece...and the next.
I did exactly that. I don't recall if it was Home Depot of Lowes; bought 10 ft lengths of black iron and had them cut into pieces and threaded. Less expensive than buying the same size precut lengths.
A Squared is offline   Reply With Quote
The Following User Says Thank You to A Squared For This Useful Post:
MT Stringer (01-01-2015)
Sponsored Links
Advertisement
 
Old 01-01-2015, 12:11 PM   #19
Member
 
MT Stringer's Avatar
 
Join Date: Oct 2008
Location: Channelview, Tx
Posts: 737
Rewards Points: 254
Default


Quote:
Originally Posted by A Squared View Post
I did exactly that. I don't recall if it was Home Depot of Lowes; bought 10 ft lengths of black iron and had them cut into pieces and threaded. Less expensive than buying the same size precut lengths.
Thanks. I spent some time browsing both websites and their prices are about the same. The prices for the shorter lengths are considerably more expensive than buying a 10 foot piece. I have a gift card for HD, so I think I will spend it on black pipe.

Thanks for all the suggestions and advice.
Mike
MT Stringer is offline   Reply With Quote
Old 01-01-2015, 01:40 PM   #20
Electrical Contractor
 
jbfan's Avatar
 
Join Date: Jun 2004
Location: Newnan GA
Posts: 7,893
Rewards Points: 444
Default


Quote:
Originally Posted by MT Stringer View Post
Thanks. I spent some time browsing both websites and their prices are about the same. The prices for the shorter lengths are considerably more expensive than buying a 10 foot piece. I have a gift card for HD, so I think I will spend it on black pipe.

Thanks for all the suggestions and advice.
Mike
Any time you buy something outside the normal packaging, you pay more.
Case in point, prepackaged wire in 25, 50, and 100' lengths
__________________
Yes I am a pirate, two hundred years too late
The cannons don't thunder, there's nothing to plunder
I'm an over-forty victim of fate.
jbfan is online now   Reply With Quote
Old 01-01-2015, 02:48 PM   #21
Member
 
Join Date: Aug 2009
Posts: 2,141
Rewards Points: 3,396
Default


Quote:
Originally Posted by bobelectric View Post
Bored one night, I tried to thread ĺ pvc to save on fittings. No comment on the results.


I came into the shop one day and found my brother cut a spoon in half.








threading pvc to save on fittings.....(wouldn't you then have to tap the couplings and connectors)
ritelec is offline   Reply With Quote
Old 01-01-2015, 05:10 PM   #22
Member
 
Join Date: Nov 2011
Location: Hartfield VA
Posts: 36,308
Rewards Points: 17,756
Default


Want a flexible never going to work pipe then go with the SCH 80 PVC pipe.
Just a silly idea.
__________________
When posting in forums, letting us know your location will help others give better feedback/advice/solutions to your questions
joecaption is offline   Reply With Quote
Old 01-01-2015, 05:14 PM   #23
Master Electrician
 
Join Date: Mar 2010
Location: Indiana
Posts: 4,309
Rewards Points: 4,874
Default


Depends on the application. To what are you referring ?
brric is online now   Reply With Quote
Old 01-01-2015, 08:03 PM   #24
Member
 
deverson's Avatar
 
Join Date: Sep 2012
Posts: 187
Rewards Points: 77
Default


Electrical threads are not the same as NPT threads. NPT Is tapered and electrical threads are straight.m
deverson is offline   Reply With Quote
Old 01-01-2015, 09:56 PM   #25
Master Electrician
 
Join Date: Mar 2010
Location: Indiana
Posts: 4,309
Rewards Points: 4,874
Default


Quote:
Originally Posted by deverson View Post
Electrical threads are not the same as NPT threads. NPT Is tapered and electrical threads are straight.m
Quite incorrect. 2011 NEC 344.28
brric is online now   Reply With Quote
The Following 2 Users Say Thank You to brric For This Useful Post:
mm11 (01-02-2015), Stubbie (01-02-2015)
Old 01-01-2015, 10:40 PM   #26
Member
 
Join Date: Dec 2005
Location: Anchorage, Alaska
Posts: 244
Rewards Points: 220
Default


Quote:
Originally Posted by deverson View Post
Electrical threads are not the same as NPT threads. NPT Is tapered and electrical threads are straight.m
That's not correct. The threads on RMC are tapered. The NEC requires that they be tapered.
Quote:
Originally Posted by NEC Article 344.28
When threaded in the field, a tapered cutting die 1 in 16 taper (ĺ in. taper per foot ) must be used.
That applies to field threading, not the factory threads on conduit, but the conduit is manufactured to ANSI C80.1 standards which also require tapered threads.

Where the confusion comes from is that the *couplings* for conduit are straight threaded.

My understanding for the reasons for this is to ensure a positive electrical connection through the joints. If you screw a tapered thread pipe into a straight thread coupling all the way, the last threads on the pipe are slightly larger tan the threads on the coupling so you get a nice tight interference fit. On the other hand, if you take a tapered die and make straight threads with it by running it onto the pipe too far, all the threads will be under diameter because they have been cut by the small end of the tapered die. Screwing such "running" threads into a straight threaded coupling would give a slightly loose metal to metal contact, which could corrode over time and degrade the electrical conductivity through the joint.

There are a few application where straight threads in conduit are permitted by code, but as far as I can tell, these all require a locknut on the connection, which draws up the threads for a tight metal to metal contact.
A Squared is offline   Reply With Quote
Old 01-01-2015, 11:03 PM   #27
Super Moderator
 
joed's Avatar
 
Join Date: Mar 2005
Location: Welland, Ontario
Posts: 18,089
Rewards Points: 22,536
Blog Entries: 11
Default


What does all that have to do with pipe clamps? Loose threads on pipe clamps are better from my point of view. It makes removing the clamp easier to change pipe lengths.
joed is online now   Reply With Quote
The Following User Says Thank You to joed For This Useful Post:
Stubbie (01-02-2015)
Old 01-01-2015, 11:20 PM   #28
Member
 
Join Date: Dec 2005
Location: Anchorage, Alaska
Posts: 244
Rewards Points: 220
Default


Quote:
Originally Posted by joed View Post
What does all that have to do with pipe clamps? Loose threads on pipe clamps are better from my point of view. It makes removing the clamp easier to change pipe lengths.
That may be, but the OP was unclear on which threads were used, and apparently other posters are unclear also.

What it has to do with pipe clamps is now that the OP knows that tapered threads are used on both plumbing pipe and conduit, he knows that either will work fine with conduit couplers which are smaller diameter than plumbing couplers and therefore more convenient for extending pipe clamps. And he won't have to worry whether the threads he gets at Home Depot are going to work with the couplings.

Last edited by A Squared; 01-01-2015 at 11:25 PM.
A Squared is offline   Reply With Quote
The Following User Says Thank You to A Squared For This Useful Post:
MT Stringer (01-01-2015)
Old 01-01-2015, 11:51 PM   #29
Member
 
MT Stringer's Avatar
 
Join Date: Oct 2008
Location: Channelview, Tx
Posts: 737
Rewards Points: 254
Default


Quote:
Originally Posted by A Squared View Post
That may be, but the OP was unclear on which threads were used, and apparently other posters are unclear also.

What it has to do with pipe clamps is now that the OP knows that tapered threads are used on both plumbing pipe and conduit, he knows that either will work fine with conduit couplers which are smaller diameter than plumbing couplers and therefore more convenient for extending pipe clamps. And he won't have to worry whether the threads he gets at Home Depot are going to work with the couplings.
Yes sir. And I appreciate all the info because I didn't know one way or the other. I think I will get some of the electrical couplings and try those. The thicker pipe couplings have been bothersome in the the past.
MT Stringer is offline   Reply With Quote
Old 01-02-2015, 06:16 AM   #30
An old Tradesmen
 
Join Date: Oct 2008
Location: Somewhere
Posts: 37,775
Rewards Points: 7,354
Default


Quote:
Originally Posted by brric View Post
Straight what? plumbing threads and electrical conduit threads are BOTH NPT tapered threads.
Electrical conduit is not/wasn't always a tapered thread. But if you used a plumbing coupling on an electrical thread, it would tighten up some, so it would seem like the pipe had a tapered thread.
__________________
When posting in certain forums, knowing your location will help others give better feedback/advice/solutions to your questions.
beenthere is offline   Reply With Quote
Sponsored Links
Advertisement
 
Reply


Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Leaking drain pipe under kitchen sink dethun Plumbing 22 03-13-2016 05:53 AM
Threading black pipe giser3546 Plumbing 11 07-06-2014 11:03 PM
Lead Drain Pipe Project Turbo98 Plumbing 33 01-30-2011 11:27 AM
four inch plastic drain pipe through concrete foundation wall dan patterson Plumbing 11 01-25-2011 06:23 AM
half Inch gas pipe Jim Skyblue Plumbing 3 01-04-2011 09:33 PM




Top of Page | View New Posts