TC-ER Tray Cable: What the -ER Means
TC-ER is Type TC tray cable that is also rated for an exposed run: it can leave the cable tray and go to the equipment without conduit, under the conditions in NEC 336.10(7). This page covers what the marking means, the conditions, and how TC-ER compares with plain TC, PLTC and MC cable.
The Short Answer
Type TC (NEC Article 336, power and control tray cable) is a factory assembly of two or more insulated conductors under a nonmetallic jacket, with or without a grounding conductor. It is made to be installed in cable tray or raceway.
TC-ER is the same cable with one more qualification. It passes the crush and impact tests required of Type MC cable and is marked "-ER" on the jacket. That marking is what allows the last stretch, from the tray to the motor, drive or panel, to be run exposed instead of in conduit.
The Conditions for an Exposed Run (NEC 336.10(7))
- Industrial establishments only, where the conditions of maintenance and supervision ensure that only qualified persons service the installation.
- The cable is identified -ER. Read the jacket print; "TC" alone does not qualify.
- Continuously supported and protected against physical damage, using mechanical protection such as struts, angles or channels.
- Secured at intervals of 6 feet (1.8 m) or less.
- Equipment ground inside the cable. In cables with conductors 6 AWG or smaller, an insulated conductor may instead be permanently re-identified as the equipment grounding conductor at installation.
- Short unsupported transitions. Where it is not subject to physical damage, TC-ER may cross between trays, or from a tray to equipment, for up to 6 feet without continuous support. It must be mechanically supported where it leaves the tray so the minimum bending radius is kept.
Summarized from NFPA 70 (NEC) Article 336. Section numbers and details change between editions, and local amendments apply; read the code text for the edition your jurisdiction enforces. This page is for reference only.
TC, TC-ER, PLTC and MC Compared
| Cable | NEC Article | Where It Runs | Exposed From Tray to Equipment? |
|---|---|---|---|
| Type TC | 336 | Cable tray, raceway, messenger wire | No |
| Type TC-ER | 336 | Same as TC, plus exposed runs | Yes, under 336.10(7) |
| Type PLTC | 725 (722 in the 2023 NEC) | Power-limited circuits, 300V | Only where marked PLTC-ER |
| Type MC | 330 | Metal-clad; exposed, tray or concealed | Yes (armored) |
Two trade names turn up on tray cable quotes. VNTC (vinyl nylon tray cable) is Type TC made with THHN-style PVC and nylon conductors under a PVC jacket. XHHW-2 tray cable uses cross-linked conductors instead, which handle heat and moisture better. Either one may or may not carry the -ER marking, so ask for it by name.
Where Type TC May Not Be Used
- Where it will be exposed to physical damage.
- Outside a raceway or cable tray system, except for the exposed runs and messenger-supported runs the article allows.
- In direct sunlight, unless the cable is identified as sunlight resistant.
- Directly buried, unless the cable is identified for direct burial.
What to Put on the Request
- The marking you need: TC or TC-ER (and sunlight resistant or direct burial, if the run needs them).
- Size and conductor count, and whether you need a ground: for example 12 AWG, 3 conductor with ground.
- Insulation: VNTC (THHN-style) or XHHW-2.
- Voltage: 600V power and control, or 300V PLTC for instrumentation.
- Shielding, if the cable feeds a drive or carries signals. For variable frequency drives, see our VFD cable.
- Footage. We cut to length.
Tray Cable on Our Stock List
Our stock part numbers include 600V VNTC tray cable, XHHW-2 power cable with ground marked TC-ER, shielded VNTC marked TC-ER, TC-ER VFD cable, and 300V PLTC instrumentation cable. Browse the tray cable part numbers, search the list for TC-ER, or see the 600V tray cable and power-limited tray cable product pages.
Frequently Asked Questions
What does ER mean on tray cable?
ER stands for exposed run. It marks a Type TC tray cable that passes the crush and impact tests required of Type MC cable, which is what NEC 336.10(7) asks for before the cable may leave the tray and run exposed to a piece of equipment.
Can TC-ER be run without conduit?
Between a cable tray and the equipment it feeds, yes, in an industrial establishment where only qualified persons service the installation. The cable has to be continuously supported, protected from physical damage with struts, angles or channels, and secured at intervals of 6 feet or less. Where it is not subject to physical damage, it may also cross up to 6 feet between trays, or from tray to equipment, without continuous support.
Can plain TC cable leave the tray?
Not as an exposed run. Without the -ER marking, Type TC stays in cable tray or raceway, or is supported by a messenger wire outdoors. If the drawing shows cable dropping out of the tray to a motor or panel without conduit, it needs to be TC-ER.
Does TC-ER need a ground wire?
For an exposed run, the equipment ground has to be inside the cable. In cables with conductors 6 AWG or smaller, NEC 336.10(7) also allows an insulated conductor to be permanently re-identified as the equipment grounding conductor at the time of installation.
Is TC-ER the same as MC cable?
No. Type MC is metal-clad cable under NEC Article 330, with an interlocked or corrugated metal armor. TC-ER has a nonmetallic jacket and no armor; it only has to meet the same crush and impact test levels as MC. Where the specification calls for armor, TC-ER does not substitute.