ECN Forum Forums Code Related Discussion NEC & other Code issues Raceway

Does anyone have a idea where in the code it refers to the use of "homemade type of conduits and pull boxes. I know that there is an article 409 for Industial Control Panels. But like a company who employ their own electricians in a food prosessing plant and the company would like them to use stainless steel tubing for a conduit to help keep the process floor clean. Use 2" SS tubing as conduit and larger SS fittings as pull boxes. ie... 6" SS flange with short pup welded on it with a welded cap onto it with 2-2" SS tubing entering at a 45 degree angle and welded to the SS pup and have a plate bolt on to the flange for a cover.

If the AHJ "approved" it you could use cardboard boxes and paper towel tubes for raceways. The reality is most AHJs cover their ass by requiring listings from a NRTL.
In some cases they will allow site built equipment if it is not readily available from a regular source. They may still want a NRTL test or them may be happy letting their inspectors approve it.

In my state job I did get the power of the pencil to approve a few things. I was pretty dilligent to see that it was equal to or better than a similar listed product.

I don't know if this helps, but I believe Hoffman makes alot of SS raceways for food and Pharmacuetical type enviroments.

All I think are UL approved.

Dnk........

Dnk, is right. I have seen stainless steel tubing used in big milk and cheese plants, where it is a corrosive enviroment.

Chris

I have been involved in a few projects where the appropriate materials either didn't exist, or were even proscribed by code.

In every case, getting approval was not difficult. A major reason for this is that not only did we have our explanation ready- we also had UL standards, NEMA standards, ANSI standards, whatever was appropriate for the item in question- and showed how we otherwise met or exceeded the standard.

One example involved the use of stainless steel pipe as conduit for a short section. We were unable to locate any manufacturer of listed stainless conduit. So we first showed the results of the environment on the listed product, then produced the standard for RMC, showed how the stainless pipe had a similar wall thickness, and certainly appeared as smooth internally as the listed product. Approval was, given that preparation, a no-brainer.

On one hand:

344.6 Listing Requirements. RMC, factory elbows and couplings, and associated fittings shall be listed.
352.6 Listing Requirements. RNC, factory elbows, and associated fittings shall be listed.
358.6 Listing Requirements. EMT, factory elbows, and associated fittings shall be listed.
342.6 Listing Requirements. IMC, factory elbows and couplings, and associated fittings shall be listed.

I see that every conduit type is required to be listed. So, a code compliant installation will not include using "homemade" conduit or using the railing on a guard wall or the top-piping on a fence for conduit.

On the other hand:

376.10 Uses Permitted. The use of metal wireways shall be permitted in the following:
(1) For exposed work
(2) In concealed spaces as permitted in 376.10(4)
(3) In hazardous (classified) locations as permitted by 501.4(B) for Class I, Division 2 locations; 502.4(B) for Class II, Division 2 locations; and 504.20 for intrinsically safe wiring. Where installed in wet locations, wireways shall be listed for the purpose.
(4) As extensions to pass transversely through walls if the length passing through the wall is unbroken. Access to the conductors shall be maintained on both sides of the wall.

I see that a "homemade" metal wireway is permitted in dry locations if it meets the construction requirements of:

376.120 Marking. Metal wireways shall be marked so that their manufacturer’s name or trademark will be visible after installation.

What kind of requirement is this? I stamp my tin-foil wireway with my logo: "cheapo-electrical supplies", and I have a code compliant installation.

Pull boxes are a different story:

(B) Thickness of Metal. Sheet steel boxes not over 1650 cm3 (100 in.3) in size shall be made from steel not less than 1.59 mm (0.0625 in.) thick. The wall of a malleable
iron box or conduit body and a die-cast or
permanent-mold cast aluminum, brass, bronze, or zinc box or conduit body shall not be less than 2.38 mm (3⁄32 in.)
thick. Other cast metal boxes or conduit bodies shall have a wall thickness not less than 3.17 mm (1⁄8 in.).

I have a construction standard for boxes, and none for wireways. I have to use listed conduit and fittings, but I can manufacture my own wireways and boxes.

Thanks for everyones input, the things you have mentioned I am aware of from code digging and/or from installing lots of SS hoffman panels and gutters. I guess I was just looking to see why we would have a code article like 409 which to me is to prohibit homemade boxes and yet nothing on raceways that are homemade.
In Western Ks. the AHJ does not do inspections outside of the city unless that county requires code inspections and those are few between. Other wise it is up to the contractor to inform the customer of NEC requirements or the company to tell the contractor what they want put in. And this seems to leave some things open to opinion like earydean sort of mentioned.
I might be way out in left field but the code is for safety of person and equipment from fire and shock.

I am all in favor of following the rules....and try hard to do so. Yet, as Judge Learned Hand of the US Supreme Court once observed, "the law is an ass."

Following the 'letter of the law' can result in silly situations, or even create a hazard. This is because no code can forsee every possible situation. One does have to consider things both in context, and from their intent.

That said, rules usually have some sort of logic behind them, and are often derived from experience- so one ought not disregard them lightly. One simply must do his homework, and not simply assert that "it'll do."

There is the principle that you can delegate authority, but not responsibility. Just because the AHJ, engineer, customer, or UL say something is OK, that does not relieve you of your responsibility. In the end, it's your call.

"Self government can't work without self-control."

DLinton,
The raceway articles all require the use of listed raceways. Stainless steel conduit is available as a listed product, so that is what should be used.
Don