Currently we use stainless steel welded processing pipe on our skids for low voltage and ss rigid electrical conduit for the 480 going to local pump motors.

Would it meet nec if we run the 480 for the local pump motors in their own welded stainless steel process pipe?

If I am correct the NEC requires raceways to be "Listed". This may or may not put a crimp in your plans.

George is on the money

Just saw this was your first post. Welcome aboard. I had a thought. What are you actually building? It may have bearing on your post.

Process pipe conforms to many plumbing codes, but not the NEC for use as conduit. My answer would be no, even though it is probably better than any other type of "listed" conduit.

Thanks for the prompt responces.

These are food and beverage processing skids.

I was afraid that it was the UL that would be the deciding factor. So our only other option would be to weld ss rigid conduit which would look like garbage.

So does that mean that our low voltage in process pipe connecting to ss nema 4x boxes is out of code?

I doubt you can weld any raceway. How would you guarantee there was no slag or rough edges inside?

Welding conduit is prohibited by NEC section 300.18:

How are the dairies getting away with this. A good number of them only except welded conduits?

No inspections?

Greg, trust me on this ... dairies get LOTS of inspections BTW, the USDA inspector trumps everyone else.

The OP is 'crossing a line' here. Once you take a bunch of equipment, cobble it together, and mount it on a skid ... the NEC no longer applies, as you have constructed an 'appliance.' The same principle applies to process equipment and assembly lines.

That's one of the real problems with the new NEC section about control panels .... there's absolutely no way for any NRTL to review what the controls are telling the machinery to do - all they can do is measure clearances.

The NEC almost starts off by stating that methods need to be suitable for the environment .... and those 'environmental' factors can easily include sanitation requirements, etc.

We can use the NEC, product standards, etc., for guidance .... but, when you're making an appliance, it comes down to your design requirements and professional judgment.

This is also the reason that the NEC recognizes the need for the AHJ to be able to disregard parts of the code. Industrial situations can very easily become "special" cases.

I may be off on this because I still am not sure what your "skid" is. My apolgies This my be cost prohibitive, but your may be able to get your "skids" listed if you mass produce (relative term) them. If the "skids" are unique from one another that you will not need to list them.

Either way they would need to be reviewed and sign off by a Electrical Engineer and the "skids" would have to assembled in an "engineer controlled environment" or by a licensed electrical contractor using listed conduits. Your local and state laws should address these matters.

If you are considering to "list" your skids, you are not limited to UL (no disrespect to UL) there are other Nationally Recognized Testing Laboratories (NRTL)

For more info to common questions on NRTL:
NRTL FAQ's

NRTL website

Underwriter Labratory listing process:
UL listing process

John what you are saying is consumer equipment is not subject to the NEC if it is not hardwired into the building wiring?
By "inspection" I was talking about the NEC inspector, not the health department.

Right, Greg ... but it's quite possible for a dairy to find itself in a conflict between different inspectors. If the USDA guy says "I want it welded, smooth, with no place for germs to collect," that's what will happen.

I said nothing about hard-wiring. Any appliance is, by definition, beyond the scope of the NEC. Open up nearly any appliance - UL listed included - and you'll easily find all manner of 'violations' in wire sizing, overcurrent protection, bend radius, and conduit fill. FWIW, you'll also see wires routed through all manner of raceways that are not recognized by the NEC.

Perhaps the simplest example is the ordinary table lamp. The cord certainly isn't #12 gauge, even though we plug it into a 20 amp circuit. That bored hole through the base isn't a recognized raceway. Yet, UL has no trouble listing it (to a non-NEC standard) because it's an appliance.

Further, as a general principle, there is no requirement that appliances be listed or approved by anyone. That many -especially consumer ones- are is the result of marketing, not regulation. Step away from the consumer marketplace, and listing marks, especially for complete assemblies, become pretty rare.

Or, as I like to point out .... Apollo 11 was NOT UL listed. Nor are the Abrams tank, the Boeing 747, the USS Enterprise, or even the family car. It just happens that we, as electricians, happen to work in the market that is most heavily penetrated by UL.

Now ... lest anyone think I'm being cavalier ... there have been times when I, or my employer, was forced to act contrary to the NEC's (or other codes') specific requirements. Such should not be done carelessly; in the instances that I participated in, there were specific reasons, and other documents (UL, NEMA standards, for instance) were referenced to identify important requirements. In short, we were able to reasonably state that the 'work around' would meet every requirement the listed product would, as well as some the listed product could not.

well put Reno!

Actually when you look at your table lamp and the NEC I would direct you to "fixture wires" and you will see the 18ga.

My real concern with welding is the inside of the pipe. I know they can weld, grind and polish stainless to make the outside look like it was always one piece of metal but the inside could look like a hacksaw blade.

I agree, that is a concern, an issue that needs to be addressed.

I think that would be case to case. Our welder fitters weld for sanitary processes and if the inside of our pipes looked like you described our piping would not be considered sanitary. If it did look like that would that be worse than an improperly reamed conduit?

I love that response! Well stated for sure.

I completely missed the OP's intent here. I thought we were speaking of field-installed material where the NEC would likely be the most likely code being referenced. True, if it is a skid-mounted or portable assembly, just like a manufactured home, the rules change dramatically.

For the record- I worked for about 4 years in a dairy where they welded stainless steel piping together on a regular basis and I can assure you there were no rough edges inside the pipe. This would still not permit to be used as a raceway per the NEC. I would not have a problem if it were parted of a listed assembly as reviewed by UL. My reason for posting is to tell you SS piping as used in a dairy is absolutely smooth both inside and out due to the special welding process and the need for sanitation and ease of cleaning.

I love that response! Well stated for sure.

I completely missed the OP's intent here. I thought we were speaking of field-installed material where the NEC would likely be the most likely code being referenced. True, if it is a skid-mounted or portable assembly, just like a manufactured home, the rules change dramatically.

Actually this is sanitary tube that is argon purge welded. The inside of the pipe is not how you described. The seam on the inside has less than an 1/8" "smooth" seam. As I stated the welds are performed by the same crew that is welding the pipes for the rest of the aseptic or sanitary food/beverage process process.

As for the skids, unfortunately even though they are simular none of them are exactly the same so I do not think that we could have them listed.

I agree this is special welding, not what
I see.

Perhaps you could get closer to the letter of the code of you pulled a cable through the pipe? I am starting to believe I would 90-4 you with THHN if you could show me the inside of some of your welds. A guy can screw up the deburring process with EMT and I just cut my finger yesterday on a rigid coupler. At a certain point we just have to ask ourselves "is this really safe?"