Every week, we talk to contractors who bought the wrong tray cable. They got too many conductors. They had no shield where they needed one. They chose the wrong insulation for a wet location. The answer is always the same: "I didn't know what to look for."
This guide fixes that. By the end, you will know exactly how to select TC-ER cable for your next industrial power distribution or motor control project. We cover conductor sizing, insulation choices like XHHW-2 versus THHN, shielding, grounding, and the critical TC-ER marking.
1. Understand Your Environment and Electrical Requirements
First, answer three questions about the installation environment.
- Wet or dry? If the cable will be in a wet location such as an outdoor tray, a manhole, or a washdown area, you need insulation rated for 90°C wet. That means XHHW-2. THHN is only rated 75°C when wet.
- Oil or chemicals? XHHW-2 resists oil and many chemicals. THHN with its nylon jacket offers moderate protection. For continuous oil exposure, choose XHHW-2.
- Sunlight? Outdoor trays require a Sunlight Resistant or UV Resistant jacket. Most black PVC TC-ER cables have this property, but you must verify the marking.
Second, make three electrical decisions.
- Determine ampacity and gauge. For a 20A control circuit, 12 AWG works. For 30A motor feeder, use 10 AWG. For 50A, use 8 AWG. For 80A, use 6 AWG. For 100A, choose 4 AWG or 2 AWG. For long runs, upsize the gauge to reduce voltage drop.
- Choose conductor count as 3/C or 4/C. 3/C means three phase conductors. The ground is separate. This is good for pure power. 4/C adds an insulated ground wire. Recommended for wet or corrosive environments.
- Decide if you need shielding. Unshielded cable costs less. Use it for power only, away from sensitive electronics and VFDs. Shielded cable has foil and a drain wire. It reduces EMI. Use it for VFD motor leads or for runs near instrumentation cables.
2. Three Real-World Cable Specifications You Will Actually Use
All examples below are UL 1277 listed TC-ER cables with a black PVC jacket.
Specification 1: 12 AWG 4/C Unshielded TC-ER – Control Circuits from PLC to Starters
- Use for: 24V DC control signals, PLC outputs, and solenoid valves. No VFD nearby.
- Why 12 AWG: It handles up to 25A at 90°C and is easy to terminate.
- Why 4/C: You get three control wires plus an insulated ground.
- Installation: Exposed in a cable tray or on J-hooks. No conduit needed.
Specification 2: 8 AWG 3/C Unshielded TC-ER – Fixed-Speed Motor Feeder
- Use for: A 5 to 15 HP motor at 460V with across-the-line starting. No VFD.
- Why 8 AWG: It is rated for 50 to 55A at 90°C. Perfect for a 15 HP motor, which draws about 21A.
- Why 3/C: Only three phase conductors. The ground is provided by the tray or a separate bare wire.
- Installation: Exposed in a ladder tray. Support the cable every 6 feet.
Specification 3: 2 AWG 4/C Shielded TC-ER – VFD Motor Lead or Long Feeder
- Use for: A 25 to 40 HP VFD-driven motor, or a long feeder over 150 feet where voltage drop matters.
- Why 2 AWG: Carries about 115A at 75°C or 130A at 90°C.
- Why 4/C: Three phases plus an insulated ground.
- Why shielded: The foil and drain wire block EMI. Ground the shield only at the drive end.
- Installation: Exposed in a tray. Keep at least 6 inches away from low-level signal cables.
3. Common Mistakes and Product Advantages at a Glance
Three mistakes we see repeatedly
- Using unshielded cable for a VFD run over 50 feet. Result: nuisance trips and erratic sensors. Fix: replace with shielded TC-ER. Lesson: when unsure, add shielding.
- Assuming all tray cable is TC-ER. Standard TC cable requires conduit for exposed runs. Only TC-ER can be installed without conduit. Always check the jacket marking.
- Using THHN in a hot, wet environment. THHN derates to 75°C when wet. In an 85°C pump room, insulation fails quickly. XHHW-2 lasts much longer. Match insulation to real operating temperature.
Key advantages contractors and OEMs appreciate
- Exposed run with TC-ER cuts labor by 50% compared to conduit. No pipe bending, no fish tape. Lay cable in tray, secure it, terminate it.
- Multiple insulation choices. Need 90°C wet rating? Choose XHHW-2. Working in a dry indoor electrical room? THHN/THWN-2 saves money.
- 3/C and 4/C options give grounding flexibility. Bare ground is fine in dry areas. In wet or corrosive environments, the insulated green ground in 4/C cables prevents corrosion.
- UL 1277 listing means no inspection surprises. TC-ER, UL 1277, gauge, and voltage rating are printed clearly on the jacket.
4. Selection Checklist and Installation Tips for Contractors
Selection checklist for your next order
From our sales team: Before you send a request for a quote, run through this checklist.
- Have you confirmed the environment? Wet, dry, oily, outdoor, or sunlight.
- Have you chosen the insulation? XHHW-2 for wet/hot/oily; THHN/THWN-2 for dry indoor.
- Have you calculated the gauge? Based on load current and distance, keep voltage drop under 3 percent.
- Have you decided on conductor count? 3/C for power only; 4/C for power plus insulated ground.
- Do you need shielding? Yes for VFD runs or near sensitive signals. No for straight power.
- Is TC-ER marking required? Almost always yes for exposed runs without conduit.
When in doubt, ask the manufacturer for a datasheet and verify the jacket printing. Do not assume.
Installation tips from the field
- Support spacing: Horizontal exposed runs – every 6 feet (1.8 m). Vertical runs – every 4.5 feet (1.4 m).
- Bending radius: Shielded cables need minimum 6× cable diameter; unshielded can go to 4×.
- Shield grounding for VFD cables: Ground shield only at the drive end. Grounding both ends creates circulating currents.
- Separation: Keep VFD output cables at least 6 inches away from control or instrumentation cables.
- Pulling tension: Do not exceed manufacturer's recommended value.
5. UL Certifications – What the Markings Mean
Our TC-ER cables meet North American safety standards. Conductors with XHHW-2 insulation comply with UL 44, which covers thermoset-insulated wires. Conductors with THHN/THWN-2 comply with UL 83, which covers thermoplastic-insulated wires. The complete tray cable assembly carries UL 1277 listing for Tray Cable with Exposed Run rating. These markings are printed on the jacket. To obtain our UL file numbers, request the certificate from our technical team.
FAQ
Q1: What is the main difference between 3/C and 4/C TC-ER cable?
A: 3/C cable has three conductors for the three phases. It does not include an insulated ground. 4/C cable adds an insulated green ground wire. For wet or corrosive areas, we recommend 4/C.
Q2: Can I use THHN/THWN-2 TC-ER cable outdoors?
A: Yes, but only if the jacket is marked Sunlight Resistant or UV Resistant. However, THHN/THWN-2 is rated 75°C when wet. For hot outdoor climates, XHHW-2 gives you a 90°C wet rating and more safety margin.
Q3: How do I know if I need shielded TC-ER cable?
A: You need shielding if you are connecting a VFD to a motor and the run exceeds 50 feet. You also need shielding if the cable shares a tray with sensitive instrumentation. For straight power without VFDs, unshielded is fine.
Q4: Is TC-ER cable rated for direct burial?
A: Only if the jacket is additionally marked DIR BUR or Direct Burial. Standard TC-ER is not rated for direct earth contact. Check the marking or use conduit underground.
Q5: Does Greater Wire offer custom TC-ER cable lengths for OEMs?
A: Yes. We manufacture TC-ER cable in standard gauges from 12 AWG to 500 kcmil, 3/C or 4/C, shielded or unshielded, with XHHW-2 or THHN/THWN-2 insulation. Contact us with your specifications.
Need a Quote for Your Next Tray Cable Project?
Tell us your load: voltage, current, and distance. Describe the environment: wet, dry, outdoor, or oily. Specify conductor count as 3/C or 4/C. Let us know if you need shielding. We will recommend the right cable – 12 AWG 4/C, 8 AWG 3/C, 2 AWG 4/C, or other gauges – and send a quote within 24 hours.
Contact us
Dongguan Greater Wire & Cable Co., Ltd.
Tel/WhatsApp/Wechat: +86 136 6257 9592
Tel/WhatsApp/Wechat: +86 135 1078 4550
Email: manager01@greaterwire.com
Website: www.greaterwire.com