I have been asked to define our end of the industry.
We manufacture skidded equipment, tanks vessels, etc., which hold a liquid for some type of processing. Be it heating, mixing with another liquid, distributing to another vessel, or whatever.
Along with these vessels are air actuated valves with limit switches; we use 24 vdc analog devices to indicate flow, pressure, and temperature.
Most of our controls are 24 vdc. The pump motors are usually 480 vac.
My question is, do we fall under NEC Article 670 (Industrial Machinery)?
Which in turn leads us to NFPA 79. If we do, can we disregard NEC Article 300 as per 300.1(b)?
It is getting to be quite a pain in the head if you know what I mean. I can’t find anything in the NEC, or other NFPA publications that clearly gives a definition of the difference between what would be house (building) wiring, and equipment (machine) wiring.
A little nudge in the right direction would be helpful.
Art. 670 seems to apply to the internal wiring of self-contained machines, or systems of machines such as might be found in metal shops, printing shops, package handling, etc, where a feeder is run to the machine. If you are building skid units that essentially mimic an installation that would otherwise be performed at a plant, it seems to me that it would be considered premises wiring, and all the applicable NEC rules would apply.
In other words,
If you feed a motor from a panel that is mounted and wired at your shop and then delivered, that should not exempt you from following the same rules that would apply if it the motor was installed from a panel at the plant.
Are these chemical processing vessels with process control instrumentation? Who do you work for and what brands of instrumentation do you use?
[This message has been edited by Redsy (edited 10-23-2002).]
#82198 - 10/23/0211:28 AMRe: Lots of Rules In the NEC Do Apply! Please Help
we design, fab, and build processing skids for the pharmaceutical industry.our skids may be used for cleaning purposes, as well as manufacturing. they would consist of vessels, pumps, valves, heat exchangers, and istruments to control the process. some of these skids are built in house and only need a power drop and airline to get them going. others may require complete disassembly at our facility, due to their size, and reassembly at the job site. we generally build these to NEMA 4X standards. our larger skids are designed to be intgrated into a larger system. controls wise. i am having trouble defining the industrial machine aspect. where is the line between industrial machine and building. one example of my problem is. we like to fab our own wireways for routing the instrument cables. we also like to include instrument airlines in the wireway. the instrument cables have no current carrying capacity. 4-20 mA analog, or 24vdc signal from a limit switch of some sort. NEC 300.8 is pretty clear about not being able to route anything other than electric conductors in the wireway. the whole design aspect of the wireways is for cleanliness. it makes the skids much easier to keep clean. this is just one example of my problem. thank-you very much for you help. dan
#82199 - 10/23/0211:48 AMRe: Lots of Rules In the NEC Do Apply! Please Help
I am not an authority on the NEC. Just a user of it. I believe that the installation of pneumatic tubing in a wireway with electrical conductors would be a violation even if it was fabbed off-site. Intuitively, I believe that Art. 670 applies to power & control wiring for control cabinets and the like that are associated with automated machinery as previously mentioned.
#82200 - 10/23/0201:47 PMRe: Lots of Rules In the NEC Do Apply! Please Help
i am also seeing a difference in opinion as to how the NEC is applied. i appears as you work in different areas of the country you get differring opinions on the code. what is acceptable in one area isn't always acceptable in another. what do you use as a baseline for construction purposes. what we are currently doing is trying to get with the engineer on the job site and have tehm help guide us. or we will contact the local inspector and discuss any issues we may have. this tends to get lengthy and time consuming. not to mention frustrating. what i am trying to do is set a standard and use it as a starting point for our construction methods. where i get hung up is the codes for industrial machinery and everything else. if i am bound to follow UL508A for my method of building panels and ocntrol enclosures, doesn't that qualify my product as an industrial machine? thank-you dan
#82201 - 10/23/0202:49 PMRe: Lots of Rules In the NEC Do Apply! Please Help
IMO if the piece of equipment is shipped as a complete assembly needing only a power hook up and an air drop, then you would use the codes for industrial machines. If it's built on site the the NEC applies.
#82203 - 10/24/0212:42 PMRe: Lots of Rules In the NEC Do Apply! Please Help
IS THERE A CODE REGARDING INSTRUMENT AIR AND HOW YOU CAN ROUTE THE LINES? PART OF OUR DESIGN PROCESS DEALS WITH THE ABILITY TO MAKE A SKID/STRUCTURE CLEANABLE. WE GO OUT OF OUR WAY TO DESIGN IN AS LITTLE OPEN CORD WHIPS, AIRLINES, AND CONDUIT RUNS. MOST OF OUR CUSTOMERS REQUEST WE ROUTE AS MUCH TOGETHER THROUGH AS LITTLE CONDUITING AS POSSIBLE. THIS IS WHERE OUR WIREWAYS COME INTO PLAY. WE ACTUALLY POP HOLES IN THE BACK AND BOTTOM OF THE WIRE WAYS TO ROUTE CORDS AND AIRLINES OUT OF.