Open Wiring Methods

[dondiggy]

I'm trying to understand Ch. 3 of the NEC (2017). Is it acceptable to use "SO" type cord to replace the liquid-tight in the picture below? The photo is of a piece of equipment we manufacture. I've decided to go with TC-ER cable, but is it acceptable to use other types of cords/cables for external runs on a piece of industrial equipment?



I'm evaluating ideas to clean up the wiring scheme for our burner control assembly. I currently use liquid-tight non-metallic conduit, and would like to evaluate other ideas for wiring between the burner control enclosure and its' peripheral instrumentation.

 

[jumper]

I am thinking that this would be a UL or whatever organization covers that equipment rather than an NEC issue.

What is your problem with the liquid tight? Seems fine to me.

 

[dondiggy]

Nothing's wrong I suppose. I'm just evaluating other wiring methods for additional cost savings, and my knowledge of the NEC in regards to exposed wiring methods is a little lacking. Also, any avenue I can find to increase my understanding of the code book, is a welcome venture.

Chapter 13 of NFPA 79 (2015) devotes a couple of sections to wiring practices with cables and cords.

Section 13.1.6.1 "Exposed cables installed along the structure of the equipment or system or in the chases of the machinery shall be permitted. Exposed cables shall be installed to closely follow the surface and structural members of the machinery." The entire section refers to "cables" and "cords" generically.

Are there NEC rules/ratings governing the type of cable allowed for this type of installation in the above referenced section (13.1.6.1)? For example, does it have to be TC-ER rated?

Ultimately, I'd like to understand what purpose "SO" type of cord(s) serve?

Any help is much appreciated, and I apologize if this is the wrong forum for these types of questions.

Thank you!

 

[al hildenbrand]

Ultimately, I'd like to understand what purpose "SO" type of cord(s) serve?

First, I direct your attention to the NFPA Glossary of Terms 2016 which is available in a link here. Looking up "cord" shows a definition specifically for NFPA 79. Compare that definition to the definition of "cable".

Chapter 13 of NFPA 79 (2015) devotes a couple of sections to wiring practices with cables and cords.

Section 13.1.6.1 "Exposed cables installed along the structure of the equipment or system or in the chases of the machinery shall be permitted. Exposed cables shall be installed to closely follow the surface and structural members of the machinery." The entire section refers to "cables" and "cords" generically.

Without seeing the code language using "cords" I can't comment about difference.

Are there NEC rules/ratings governing the type of cable allowed for this type of installation in the above referenced section (13.1.6.1)? For example, does it have to be TC-ER rated?

Derek, above, has already pointed at this, but, if you'll allow me, consider: NFPA 70, the National Electrical Code, is, essentially, regulating the installation of the Premises Wiring (System) from the connection to the Electric Utility to the "Outlet." The "Outlet" is a point on the wiring system where current is taken for utilization equipment.

As a manufacturer of a "utilization equipment" you have to ask yourself, "What wiring is required to be installed to your utilization equipment by your customer's electrician?" As a generalization, the point at which you provide, in your manufactured equipment, an electrical termination point for your customer's electrician's field installed Premises Wiring, THAT is the "Outlet" and is the legal boundary of the NEC (NFPA 70). The wiring that your factory assembles is NOT field installed, and is therefore regulated by other NFPA standards.

 

[Aleman]

As far as the code goes with TC-ER cable, I believe you can make those runs with cable without conduit. The reason I would not
do that in your application is that even though the TC-ER is rated for crush and impact resistance, your cables will get stepped
on. Can you run those across the flat area in covered tray and then break out to your various components? We use a lot of TC-ER
cable and keep exposed runs away from physically being bumped or stepped on. I am assuming the reason to change your method is to
reduce cost. Otherwise the way you build now is legit and the right way to do it. That's my opinion anyhow.