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.

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.

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).

Not my first choice either but give the customer what they want.

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:

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

I thought that was only ABS plumbing pipe that did that. The black PVC.

The emission of the gases it produces is why it is not permitted in a plenum. See 300.22

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

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

What is Robroy?

GJ, sorry, it's PVC coated ridgid.

Roger

Assorted killer-conduit sites…
www.plastibond.com www.permacote.com www.robroy.com www.korkap.com www.calpipe.com www.stainlessconduit.com

Thanks Bjarney.

Roger

If I recall corectly, RNC is CPVC. Which is lower smoke emmision than PVC.

"GJ, sorry, it's PVC coated ridgid.
Roger"

No need to be sorry. I learned something new, so the day wasn't a complete loss.

GJ

Have used PVC conduit in sweveral different type of plants all of which have somewhat nasty enviromental work areas. If the are large temp changes even a lot of expansion joints will not keep the install from looking bad in a couple of years. But it's a lot easier and much much cheaper than Robroy. If a customer needs robroy or other PVC coated rigid, prepare them for severe sticker shock. Also get a good count of couplings, connectors, and other hard ware. It's all expensive and an extra cost. You will need special tools to install, cut and thread it also
I also hate that stuff

That is very true, be ready to provide CPR when you give the customer the price.

One of our guys did a job in a hazardous location with PVC coated RMC.

What a pain in the rear!

Short an LB or a junction box, the job stops for days to weeks to get the expensive parts out to the job, not shelf items at any supply houses we deal with.

Even PVC coated 1 hole clips with stand offs had lead time and a high price.

I installed a 480 volt 30 amp 3 phase PVC coated hazardous location receptacle and matching cord cap, they told me just that was over $2,000.

The receptacle had a switch in it that killed a contactor outside the hazardous area when you started to remove the cord cap.

I like EMT and MC.

Don't most non-wool carpets give off the same fumes?

I hope not.

Almost all of the furnishings used in a house give off fumes that are every bit as toxic as the nonmetallic conduit fumes. In my opinion, in most types of buildings, the toxic fumes given off by burning building materials are so much less than those given off by the burning contents and furnishings in the structure that the fumes from nonmetallic conduit or plumbing piping are almost insignificant. By the way, wool produces cyanide gas when it burns.
Don

Don, thanks;
I sure wish you could wake up some of the building departments out here in SoCA.
As I look around the spot I'm sitting right now, I see almost nothing but plastics.
How much can a conduit system contribute to this if it were to burn?
To use PVC as an indoor premise wiring system here would result, I think, in a red tag 9 times out of 10.
I got a very "mad" correction notice once for installing a section of 2" PVC80 for a phone line on the roof of a restaurant in Newport Beach---the threat of chlorine gas.
In the next city North, Huntington Beach, it is a requirement to use PVC80 on a rooftop, or use $70 a gallon marine grade paint to paint the entire installation of your metallic conduit.
They're separated by the Santa Ana River, about 150 yards wide.

I saw my van burn to the ground, that's about all the exp I have with fire, but I'm sure that a couple of pieces of PVC conduit wouldn't have made much difference in the show, nor its danger...S

Almost all of the PVC conduit used out here is either underground, underslab, in masonry or concrete walls, or outdoors.



[This message has been edited by electure (edited 02-19-2004).]

Hang on Guys!,
We use PVC over here in New Zealand exclusively in Commercial and Industrial Installations.
PVC is (these days, at least) Flame Retardant, Self Extinguishing.
At least the stuff we have here is.
WE don't use EMT or IMC over here.
For real rugged uses we usually use HFT grade(Black) PVC conduit or for Boiler rooms and the like we use Pyrotenax MIMS (Mineral-Insulated-Metal-Sheathed cables).
PVC has the advantages of not having to be threaded, is easy to work with and it is light in weight.
Disadvantages are that, with it being a Thermosetting material, a given length of PVC will expand and contract under temperature changes and expansion couplings have to be used in any decent run of conduit.
Here's a strange one, care of one of my older Electrician's textbooks: If PVC conduit is used, a seperate Earth Continuity Conductor must be added.
Duh!!.
Steel conduit used to be used as the Earth(grounding) Conductor here, when we used the stuff.