PLTC Cable Outside of Cable Tray

[Slplsnts]

Thank you for taking the time to review this.

We have several discrete signal and serial cables that are snaking around a machine located in a Class 1 Div 2 area. The machine supplier would like to use P clamps and structure to support the cable and not cable tray or conduit due to the routing. From 725 Industrial Locations, it looks like the cable can be outside of tray or transitioning between tray a maximum of 6'.
Is it accurate that the cable, which is over 20 feet can not use P clamps or similar support every 6', it must be in tray to protect the cable. The 6' is to transition from tray to tray or tray to enclosure?

Second question is, many sensor manufacturers such as Rockwell or Turk provide a cable for the device either integral or connectorized and recommends the cable on the control drawing. The sensor cables are not marked, are they assumed PLTC, ITC, something else? What are the installation rules if something else?

Thank you

 

[rbalex]

Since you mention a control drawing, I assume an IS or NI installation. Note such installations would usually recognize any generally accepted wiring method, but I caution proper grounding / bonding can often be overlooked.

The answer to your first question can seem fairly convoluted. Type PLTC is specifically permitted in Division 2 by [2023] Section 501.10(B)(1)(3). Note it says,”... including installation in cable tray systems”; I.e., the tray is not necessarily required. So, with the other restrictions indicated in the section, PLTC is permitted in any wiring method otherwise excepted in the appropriate NEC Edition. The installation requirements in The 2023 NEC are in Section 722.135. Other Editions may apply, but the requirements are essentially the same.

There may be a bit more caution necessary with the sensors; however, if the cables are an integral part of the listed assembly and installed per the appropriate control drawing, they should be acceptable in Division 2 also.

 

[Slplsnts]

To clarify the control drawing, in a CI D1 installation, a barrier is shown. In CI D2, there is no barrier required and no mention of NI requirements.

Where our concern lies with the installation of PLTC and sensor cables does come form the installation requirements in 725.135 (J)(1) ... for such use shall be permitted to be exposed between the cable tray and the utilization equipment or device. The cable shall be continuously supported and protected against physical damage using protection such as dedicated struts, angles, or channels. The cable shall be supported and secured at intervals not exceeding 1.8m (6ft)...

I don't see a section here that would allow a 20' cable to be installed and supported every 1.8m using P clamps. There is mention of tray and continuous support in 725.135 but I don't know what constitutes continuous. Can there be several small sections between each 1.8m interval... The routing is no where near a straight path.

 

[rbalex]

In that case, the control drawing is effectively just an installation drawing. It still needs to be observed as manufacturer's instructions but has no effect on IS or NI wiring methods, especially in Class I, Division 2. [See Section 501.10(B)(1) in virtually any actively adopted NEC Edition]

Which NEC Edition are you using? I would prefer not bouncing between editions. In the 2023 edition effectively gives Type PLTC its own article [Art 722]. Article 725 may no longer apply. What I said earlier, “...with the other restrictions indicated in the section, PLTC is permitted in any wiring method otherwise excepted in the appropriate NEC Edition.”, is still true.

My “gut feel” is, as long as you use the appropriate Edition’s wiring method, the “recognized” PLTC securing and support requirements are acceptable in Class I, Division 2.

 

[Slplsnts]

Thank you very much for taking the time to reply. I was using NEC 2017 initially and now have 2023. Article 722.135 has the same verbiage as did 725.135. I am still reviewing this for any added gems.

 

[rbalex]

Thank you very much for taking the time to reply. I was using NEC 2017 initially and now have 2023. Article 722.135 has the same verbiage as did 725.135. I am still reviewing this for any added gems.

You’re welcome. What I was referring to as the “appropriate edition” means the currently adopted for your jurisdiction.