336.10 Uses permitted.
Code Change Summary: Changes were made to the uses permitted for Power and Control Tray Cable (Type TC).
For quite some time, the incorrect use of Tray Cable has created conflict almost everywhere. HVAC companies often try and use Tray Cable as a wiring method between the outdoor and indoor units of a split system HVAC installation. Sometimes the equipment supply house sells the TC cable with the HVAC unit and assumes that it can be used without a raceway simply because the cable is marked TC-ER (ER = exposed run). For many years, the NEC® has prohibited these types of installations in Section 336.12.
In the 2017 NEC®, new language was added to allow TC-ER cable to be run without a raceway in one- and two-family dwelling units as long as the cable contains BOTH power and control conductors and is identified for pulling through structural members. The new informational note states that TC-ER cable marked “JP” is suitable for pulling through structural members. The “JP” abbreviation stands for Joist pull.
As part of the testing and listing process, a TC-ER-JP undergoes additional testing similar to Nonmetallic-Sheathed Cables often used in a dwelling. The cable must not show signs of damage after being subjected to pulling the cable through several studs with the holes being staggered to a specific degree.
If installing the Type TC-ER-JP in a dwelling, the cable is required to be installed per the requirements of Part II of Article 334 (Nonmetallic-Sheathed Cable). This includes things like securing and supporting and specific installation techniques required in unfinished basements and crawl spaces.
Another change now allows the cable to be directly buried if it is identified for such use.
Below is a preview of Article 336. See the actual NEC® text at NFPA.ORG for the complete code section. Once there, click on their link to free access to the 2017 NEC® edition of NFPA 70.
2017 Code Language:
336.10 Uses Permitted.
Type TC cable shall be permitted to be used as follows:
(1) For power, lighting, control, and signal circuits.
(2) In cable trays, including those with mechanically discontinuous segments up to 300 mm (1 ft).
(3) In raceways.
(4) In outdoor locations supported by a messenger wire.
(5) For Class 1 circuits as permitted in Parts II and III of Article 725.
(6) For non–power-limited fire alarm circuits if conductors comply with the requirements of 760.49.
(7) Between a cable tray and the utilization equipment or device(s), provided all of the following apply:
- The cable is Type TC-ER.
- The cable is installed in industrial establishments where the conditions of maintenance and supervision ensure that only qualified persons service the installation.
- The cable is continuously supported and protected against physical damage using mechanical protection such as struts, angles, or channels.
- The cable that complies with the crush and impact requirements of Type MC cable and is identified with the marking “TC–ER.”
- The cable is secured at intervals not exceeding 1.8 m (6 ft).
- Equipment grounding for the utilization equipment is provided by an equipment grounding conductor within the cable. In cables containing conductors sized 6 AWG or smaller, the equipment grounding conductor must be provided within the cable or, at the time of installation, one or more insulated conductors must be permanently identified as an equipment grounding conductor in accordance with 250.119(B).
Exception to (7): 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.
(8) Where installed in wet locations, Type TC cable shall also be resistant to moisture and corrosive agents.
(9) In one- and two-family dwelling units, Type TC-ER cable containing both power and control conductors that is identified for pulling through structural members shall be permitted. Type TC-ER cable used as interior wiring shall be installed per the requirements of Part II of Article 334.
Exception: Where used to connect a generator and associated equipment having terminals rated 75°C (140°F) or higher, the cable shall not be limited in ampacity by 334.80 or 340.80.
Informational Note No. 1: TC-ER cable that is suitable for pulling through structural members is marked “JP.”
Informational Note No. 2: See 725.136 for limitations on Class 2 or 3 circuits contained within the same cable with conductors of electric light, power, or Class 1 circuits.
(10) Direct buried, where identified for such use.