Type W Cable Ampacity Chart
Allowable ampacity for Type W portable power cable from 8 AWG to 500 MCM, per NEC Table 400.5(A)(2), for single conductor and 2 to 5 conductor cable. Type W is the 2000V, 90°C cable used for generator feeders, temporary power distribution and mining equipment.
Type W Ampacity by Size (90°C Cable, 30°C Ambient)
| Size | Single Conductor (Column D) | 2 Conductor (Column E) | 3 or 4 Conductor (Column F) | 5 Conductor (F × 0.80) |
|---|---|---|---|---|
| 8 AWG | 80 A | 74 A | 65 A | 52 A |
| 6 AWG | 105 A | 99 A | 87 A | 70 A |
| 4 AWG | 140 A | 130 A | 114 A | 91 A |
| 2 AWG | 190 A | 174 A | 152 A | 122 A |
| 1 AWG | 220 A | 202 A | 177 A | 142 A |
| 1/0 AWG | 260 A | 234 A | 205 A | 164 A |
| 2/0 AWG | 300 A | 271 A | 237 A | 190 A |
| 3/0 AWG | 350 A | 313 A | 274 A | 219 A |
| 4/0 AWG | 405 A | 361 A | 316 A | 253 A |
| 250 MCM | 455 A | 402 A | 352 A | 282 A |
| 350 MCM | 570 A | 495 A | 433 A | 346 A |
| 500 MCM | 700 A | 613 A | 536 A | 429 A |
Allowable ampacity per NFPA 70 (NEC) Table 400.5(A)(2), 90°C columns, for copper conductors at 30°C (86°F) ambient. Column D applies to single-conductor cable only where the individual conductors are not installed in raceway and are not in physical contact with each other, except for lengths up to 24 inches where they pass through the wall of an enclosure. Column E applies when two conductors carry current and column F when three do; on a 4 conductor cable the fourth conductor is the ground. The 5 conductor figures apply the 80% adjustment of 400.5(A)(3) for four current-carrying conductors, which applies when the neutral has to be counted (for example, where most of the load is nonlinear). Where the neutral does not count, a 5 conductor cable uses column F. Confirm against the NEC edition your jurisdiction enforces. This chart is for reference only; consult a licensed electrical engineer for your installation.
We stock Type W from 8 AWG through 500 MCM in single conductor and 2 to 5 conductor constructions. Part numbers and weights for each one are in the table on the Type W cable page.
Single-Conductor Type W at the Termination
The cable's own rating is the 90°C figure, but the connection at each end can be the limit. NEC 110.14(C) holds a circuit to the temperature rating of its terminations, and unless the equipment is listed and marked otherwise, termination provisions are based on Table 310.16. That gives three numbers for the same cable:
| Size | Table 400.5(A)(2) Column D, 90°C | Table 400.5(A)(2) Column D, 75°C | Table 310.16, 75°C (Ordinary Lugs) |
|---|---|---|---|
| 8 AWG | 80 A | 70 A | 50 A |
| 6 AWG | 105 A | 95 A | 65 A |
| 4 AWG | 140 A | 125 A | 85 A |
| 2 AWG | 190 A | 170 A | 115 A |
| 1 AWG | 220 A | 195 A | 130 A |
| 1/0 AWG | 260 A | 230 A | 150 A |
| 2/0 AWG | 300 A | 265 A | 175 A |
| 3/0 AWG | 350 A | 310 A | 200 A |
| 4/0 AWG | 405 A | 360 A | 230 A |
| 250 MCM | 455 A | 405 A | 255 A |
| 350 MCM | 570 A | 505 A | 310 A |
| 500 MCM | 700 A | 620 A | 380 A |
- Ordinary 75°C lugs on a breaker, switch or panel: use the Table 310.16 column. That is 230 A for 4/0 and 175 A for 2/0.
- Equipment listed and marked for a higher value with portable cable: follow the marking on the connector or panel, and never exceed the Table 400.5(A)(2) figure for the cable.
- Derating for heat or bundling starts from the 90°C figure, then the result is compared with the termination limit. The lower number governs.
If you are sizing a generator or distribution feeder, call us at (918) 622-1489 with the load and the equipment at each end.
Derating for Heat and Extra Conductors
Ambient temperature. The table assumes 30°C (86°F). For hotter locations multiply the 90°C figure by about 0.96 at 35°C, 0.91 at 40°C, 0.87 at 45°C or 0.82 at 50°C. A single-conductor 4/0 on a 40°C (104°F) day is 405 × 0.91, about 368 A.
More than three current-carrying conductors. NEC 400.5(A)(3) reduces the column F figure to 80% for four to six current-carrying conductors and 70% for seven to nine. The ground never counts. A neutral that carries only the unbalanced current of the other conductors does not count either; it counts where most of the load is nonlinear and it carries harmonic current.
Cable left on the reel. A coiled cable cannot shed heat the way a cable laid out can. Pull off what the run needs, or ask the cable maker for its reel derating factors.
How to Use This Chart
- Find the load current. Use the generator or equipment nameplate. For continuous loads, multiply by 1.25.
- Pick the construction. Single conductors, spaced apart, for large feeders; 3 or 4 conductor for three-phase equipment; 5 conductor where a neutral and a ground are both needed.
- Read the matching column and take the first size that meets or exceeds the load after derating.
- Check the terminations against the second table.
- Check voltage drop on long runs with the wire size calculator.
Type W Next to SOOW and DLO
SOOW cord is the 600V choice up to 2 AWG; its ratings are on the SOOW cord ampacity chart. DLO cable is a 2000V single conductor that is also listed RHH/RHW-2 for conduit and tray; see the DLO ampacity chart. Our Type W vs SOOW guide covers when each one is the right pick.
Frequently Asked Questions
What is the ampacity of 4/0 Type W cable?
Per NEC Table 400.5(A)(2) at 30°C ambient, 90°C single-conductor 4/0 Type W is 405 amps when the conductors are spaced apart and not in raceway. 4/0 two-conductor cable is 361 amps, and three-conductor or four-conductor cable with three current-carrying conductors is 316 amps. Where the cable lands on ordinary 75°C lugs, the termination is limited to 230 amps unless the equipment is listed and marked for more.
What is the ampacity of 2/0 Type W cable?
300 amps as a single conductor, 271 amps for two-conductor cable and 237 amps for three-conductor cable, per NEC Table 400.5(A)(2) for 90°C cable at 30°C ambient. A five-conductor 2/0 cable with four current-carrying conductors is 190 amps.
Why is single-conductor Type W rated higher than multi-conductor?
The single-conductor column assumes the cables are spaced apart in free air, not in raceway and not touching, so each one sheds its own heat. Inside a multi-conductor cable the conductors heat each other under one jacket, so the table gives a lower figure.
Can I size a feeder on the 90°C Type W ampacity?
Only if both ends allow it. NEC 110.14(C) limits a circuit to the temperature rating of its terminations, and unless the equipment is listed and marked otherwise, terminations are sized from Table 310.16. On ordinary 75°C lugs that is 230 amps for 4/0 copper. The 90°C figure is still the starting point for ambient and bundling derating.
Type W or SOOW: which carries more?
At the same size they are close, but SOOW stops at 2 AWG, which is 95 amps with two current-carrying conductors and 80 amps with three. Type W continues to 500 MCM and is rated 2000V against 600V. See the SOOW cord ampacity chart.