ECN Electrical Forum - Discussion Forums for Electricians, Inspectors and Related Professionals

Topic Options
Rate This Topic
#93156 - 05/05/05 05:12 PM pvc expansion joints
mike collins Offline
Member
Registered: 05/04/05
Posts: 15
Loc: Quincy
running three hundred feet of 4inch pvc pipe horizontly on outside of building. table 352.44A talks about amount of expansion but iam confused about at what intervals do I need a expansion joint.
_________________________
dukes
Top
2017 / 2014 NEC & Related Books and Study Guides
#93157 - 05/05/05 05:19 PM Re: pvc expansion joints
iwire Offline
Moderator
Registered: 01/05/03
Posts: 4391
Loc: North Attleboro, MA USA
The NEC does not tell us how many expansion joints would be needed.

It depends on the amount of temperature change and the amount of movement provided by the expansion joint.

In the last few days I have been using some expansion joints from Carlon that state right on them to use one every 30'
_________________________
Bob Badger
Construction & Maintenance Electrician
Massachusetts
Top
#93158 - 05/05/05 05:37 PM Re: pvc expansion joints
mike collins Offline
Member
Registered: 05/04/05
Posts: 15
Loc: Quincy
Thanks for the reply. It would be more cost effective to run steel?
_________________________
dukes
Top
#93159 - 05/05/05 09:14 PM Re: pvc expansion joints
George Little Offline
Member
Registered: 01/18/04
Posts: 1488
Loc: Michigan USA
Bob- How do you set your expansion joints with relation to the temperature and how does the inspector check this?
_________________________
George Little
Top
#93160 - 05/06/05 02:38 AM Re: pvc expansion joints
iwire Offline
Moderator
Registered: 01/05/03
Posts: 4391
Loc: North Attleboro, MA USA
George the expansion joints that I have been using have instructions on each joint.

They do not say anything about how to set them dependent on temp, but I have wondered the same thing as you.

What they have is a scribe mark that shows how far to insert the PVC, that mark seems to be in the mid point.

I imagine if they are all set in the mid point and installed every 30' as instructed they will be enough overlap to deal with higher or lower temps than the day of installation.

These new joints are only about 6" long overall in 1.25" raceway and only cost a little more than a coupling.
_________________________
Bob Badger
Construction & Maintenance Electrician
Massachusetts
Top
#93161 - 05/06/05 04:01 AM Re: pvc expansion joints
Joe Tedesco Offline
Member
Registered: 10/07/00
Posts: 2749
Loc: Boston, Massachusetts USA
Go to www.nema.org and download the following for free:

Expansion Joints for PVC Rigid Nonmetallic Conduit NEMA Standards Expansion Joints for PVC Rigid Nonmetallic Conduit

Status: Active
[No Document Number]

This guide provides information about when and how expansion joints are used. Discusses that fluctuations in temperature have a greater effect upon polyvinyl chloride (PVC) than more traditional construction materials, such as aluminum and steel.

Thermal expansion and contraction have significant effects on long, straight runs of conduit; therefore, expansion joints are used to accommodate changes in length. This prevents potentially harmful stresses in the conduit itself or in any supporting structures.

Electronic Copy
$0.00 [DOWNLOAD]
_________________________
Joe Tedesco, NEC Consultant
Top
#93162 - 05/06/05 05:23 AM Re: pvc expansion joints
George Little Offline
Member
Registered: 01/18/04
Posts: 1488
Loc: Michigan USA
Thanks Joe. Good information for all of us.
_________________________
George Little
Top
#93163 - 05/06/05 12:33 PM Re: pvc expansion joints
HotLine1 Offline


Member
Registered: 04/03/02
Posts: 6778
Loc: Brick, NJ USA
Gentlemen:
In addition to Joe's info...Carlon has expansion joint info within their catalog. It also is available on there website.

Their tables, and a few easy calc's explain the 'setting' of the expansion joint.

John
_________________________
John
Top

Member Spotlight
Member Since: 01/22/05
Posts: 5316
New in the Gallery:
SE cable question
Featured:

2017 NEC and Related
2017 NEC
Now Available!

Shout Box


Who's Online
0 registered (), 95 Guests and 10 Spiders online.
Key: Admin, Global Mod, Mod
 
New in the Gallery:
SE cable question
 
Top Posters (30 Days)
Admin 47
HotLine1 43
gfretwell 19
Ruben Rocha 12
Trumpy 9
 
Newest Members
Scotto, Freecrowder, clee512, Jdscott2005, FAIZAN

ECN Electrical Forums - sponsored by Electrical Contractor Network - Electrical and Code Related Discussion for Electrical Contractors, Electricians, Inspectors, Instructors, Engineers and other related Professionals