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#34596 02/17/04 12:03 AM
Joined: Jul 2002
Posts: 20
S
Member
I have been asked if I can run PVC conduit for eveything in a plant, 480v feeders and low voltage. I can't see anything in the code book that say's I can't. Am I missing something? It doesn't seem very safe unless you bury it.

#34597 02/17/04 12:06 AM
Joined: Aug 2003
Posts: 1,374
R
Moderator
Unless you have some strange things, such as classified locations or plenums, you can use RNC just about anywhere. I'm not saying that it would be my first choice, but is very versatile in its uses permitted.


Ryan Jackson,
Salt Lake City
#34598 02/17/04 01:54 AM
Joined: Mar 2001
Posts: 333
S
Member
Check with the local building department for any amendments. I know of at least one local city that won't allow any plastic inside(no MC, AC or flex either).


Steve
#34599 02/17/04 05:47 AM
Joined: Jan 2003
Posts: 4,391
I
Moderator
Not my first choice either but give the customer what they want. [Linked Image]

If you end up doing this really look at the support requirements. Table 352.30(B)

1/2", 3/4" and 1" all require supports every 3 feet

Even 4" requires a support every 7 feet.

These supports "shall be fastened so that movement from thermal expansion or contraction is permitted." 352.30

This means do not use something like a EMT minni or a standard uni strut clip, you must use proper PVC supports that let the PVC slid through them.

Expansion fittings, plan on a lot of these.

IMO it is tough to make PVC look good over a long period of time.

Depending on building construction the support requirements could break the budget.

Say it is a steel truss building that has a 5' to 6' spacing, how will you support every 3'? eek:


Bob Badger
Construction & Maintenance Electrician
Massachusetts
#34600 02/17/04 10:48 AM
Joined: Dec 2003
Posts: 751
E
Member
When PVC (poly-vinyl-cloride) burns it emits a very nasty black smoke that contains clorine gas. Is this a concern to the folks in your plant? Nobody plans on having fires, but when or if they occur, will this gas be a problem for evacuation?

Earl


Earl
#34601 02/17/04 04:42 PM
Joined: Jan 2004
Posts: 615
J
Member
I thought that was only ABS plumbing pipe that did that. The black PVC.

#34602 02/17/04 04:46 PM
Joined: Aug 2003
Posts: 1,374
R
Moderator
The emission of the gases it produces is why it is not permitted in a plenum. See 300.22


Ryan Jackson,
Salt Lake City
#34603 02/17/04 06:57 PM
Joined: Apr 2001
Posts: 507
G
Member
We have rewired parts of a fertilizer plant in all pvc and plastic enclosures.

Nema 12R discos that are less than 5 years old are hardly recognizable on the outside. Inside they are still like new. It's a really nasty environment.

They are slowly replacing all the conveyors and bucket elevators with stainless steel equipment.

Plastic may not offer much impact protection, but it's better than switches that won't operate due to corrosion.

GJ

#34604 02/17/04 07:30 PM
Joined: May 2002
Posts: 1,716
R
Member
Although all the above reasons for not using PVC for this type of installation are valid, the reason for using it is as GJ says.

I think besides Stainless Steel or Robroy, (which I hate) it is the only way to go in corosive environments.

Roger

#34605 02/17/04 09:03 PM
Joined: Apr 2001
Posts: 507
G
Member
What is Robroy?

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