TC-ER Cable Use

[jmanderson]

Code states that TC-ER may be used for exposed run to utilization equipment, providing the cable runs from cable tray to the equipment.

Question is, can the cable be run leave a conduit via some sort of compression fitting and go directly to a motor for instance?

 

[augie47]

The way I see 336.10 exception, TC cable can only run unsupported for a distance of 6 ft and even then originating at the cable tray.

 

[jusme123]

The way I see 336.10 exception, TC cable can only run unsupported for a distance of 6 ft and even then originating at the cable tray.

TC-ER Rated Cables
As an option, Belden offers all PVC-nylon/
PVC, XLPE/PVC and XLPE/CPE jacketed
tray cables with a TC-ER (Exposed Run)
rating, formerly referred to as Open Wiring.
Per NEC Article 336, a TC-ER rated cable
may be installed in an industrial establishment
between a cable tray and the utilization
equipment or device. A TC-ER rated cable
must meet the crush and impact requirements
of UL Type MC cable. By eliminating
the need for metal conduit and/or armor,
using a TC-ER rated cable results in
savings in both installation and maintenance.

 

[rbalex]

TC-ER Rated Cables
As an option, Belden offers all PVC-nylon/
PVC, XLPE/PVC and XLPE/CPE jacketed
tray cables with a TC-ER (Exposed Run)
rating, formerly referred to as Open Wiring.
Per NEC Article 336, a TC-ER rated cable
may be installed in an industrial establishment
between a cable tray and the utilization
equipment or device. A TC-ER rated cable
must meet the crush and impact requirements
of UL Type MC cable. By eliminating
the need for metal conduit and/or armor,
using a TC-ER rated cable results in
savings in both installation and maintenance.

Don't be misled by advertising - it's sorta true, but incomplete. While it eliminates the need for "metal conduit and/or armor," it doesn't eliminate the support/securing reqirements.

336.10 (7) Exception: Where not subject to physical damage, Type TC-ER shall be permitted to transition between cable trays and between cable trays and utilization equipment or devices for a distance not to exceed 1.8 m (6 ft) without continuous support. The cable shall be mechanically supported where exiting the cable tray to ensure that the minimum bending radius is not exceeded.

I've been a proponent for TC-ER as an "open" wiring method both through direct Proposals and my former participation in API's Subcommittee on Electrical Equipment. With both its fire and mechanical properties, TC-ER is obviously superior to Type NM (in any form), but isn't permitted in many applications where NM would be. CMP7's primary written objection is "But, but, but - it's TRAY cable; it must be in a tray for some part of the run" - except when it's on a messenger [336.10(4)]. Since they also control Art 334 (NM), they are well aware that TC-ER is superior. IMO, the real reason is the manufacturers that also make Type MC (Art 330) don't want TC-ER cutting into the MC business. BTW Type MC has pretty much the same securing/supporting requirements. [See Section 330.30]

There is also a legitimate issue, that a certain number of crush and impact "failures" are permitted by UL 1569, the Type MC standard. According to one manufacturer's rep, while TC-ER passes within the failure limits, Type MC never fails. As far as I know, that is undocumented. It hasn't been used by CMP7 to my knowledge.

Having said all that, proper securing/supporting TC-ER at 6' intervals is a requirement and can't be eliminated.

 

[rbalex]

...Question is, can the cable be run leave a conduit via some sort of compression fitting and go directly to a motor for instance?

Yes, as long as there is not more than 6' of unsupported cable. The other requirements of Art 336 in general and Section 336.10(7) in particular also must be observed; i.e., industrial application, part of the run is in tray, protected against mechanical damage, integral EGC, etc.

 

[jusme123]

....the OP made it seem as though the TC-ER cable exited the cable tray in a conduit, and then terminated at a motor. The cable would be supported inside the conduit.

 

[jusme123]

Don't be misled by advertising - it's sorta true, but incomplete. While it eliminates the need for "metal conduit and/or armor," it doesn't eliminate the support/securing reqirements.


There is also a legitimate issue, that a certain number of crush and impact "failures" are permitted by UL 1569, the Type MC standard. According to one manufacturer's rep, while TC-ER passes within the failure limits, Type MC never fails. As far as I know, that is undocumented. It hasn't been used by CMP7 to my knowledge.

Having said all that, proper securing/supporting TC-ER at 6' intervals is a requirement and can't be eliminated.

...let me guess, it was a MC manufacturer?:slaphead: :roll:

 

[rbalex]

....the OP made it seem as though the TC-ER cable exited the cable tray in a conduit, and then terminated at a motor. The cable would be supported inside the conduit.

Support inside the conduit is fine.

...let me guess, it was a MC manufacturer?:slaphead: :roll:

Of course; as I said, his company makes both. He's actually a "go-to" guy for me and I tend to believe him. I was a major player in the development of MC-HL and I'm familiar with the crush and impact tests in UL 1569. That there is a permitted failure rate is definitely true; however, that TC-EL only passes within the permissible failure rate and MC never fails is what I've never seen documented. If it is accurate, I'm surprised it hasn't shown up in the Comments or in CMP7's Panel Statement. Technically, running TC-EL in one foot of cable tray near the "source" (it can only be run "open" between the tray and utilization equipment or device) meets the "cable tray" requirement. It still doesn't really explain why TC-EL can't be an "open" wiring method within the other installation constraints of Article 336.