Cord columns
Column A is for three current-carrying conductors, column B for two: 12 AWG is 20 A or 25 A, 10 AWG 25 or 30 A, 6 AWG 45 or 55 A. Correct for ambient temperature with Table 310.15(B)(1).
SOOW cord & DLO cable ampacity chart
SO and SOOW cord ampacity from NEC Table 400.5(A)(1): 12 AWG carries 20 A with three current-carrying conductors, 25 A with two. DLO cable follows Southwire’s data: 4/0 DLO in free air is 405 A at 90 °C, but only 260 A three to a raceway.
04 · Extension cord gauge
20 A tool, 100 ft cord · 120 V, under 5 % drop
USE:
10 AWG EXTENSION CORD (10/3) · 30 A CORD RATING · 100 FT MAX
Cord gauge
10 AWG
3-conductor
Cord rating
30 A
Table 400.5(A)(1)
Length
100 ft
A 20 A load 100 ft from the outlet needs at least 10 AWG cord to stay under 5 % drop at 120 V and within the cord’s 30 A rating.
- Cord rating 30 A ≥ 20 A400.5(A)(1)
Cord
- Gauge
- 10 AWG
- Drop at this size
- 3.40 %stranded copper at 20 °C
Portable cord and DLO tables 30 rows
Sort any column, print a shop sheet, download CSV. Click a row to load it in the calculator.
| 18 AWG | 7 A | 10 A | 7.95 |
|---|---|---|---|
| 16 AWG | 10 A | 13 A | 4.99 |
| 14 AWG | 15 A | 18 A | 3.14 |
| 12 AWG | 20 A | 25 A | 1.98 |
| 10 AWG | 25 A | 30 A | 1.24 |
| 8 AWG | 35 A | 40 A | 0.778 |
| 6 AWG | 45 A | 55 A | 0.491 |
| 4 AWG | 60 A | 70 A | 0.308 |
| 2 AWG | 80 A | 95 A | 0.194 |
Correct for ambient temperatures other than 30 °C with Table 310.15(B)(1); more than three current-carrying conductors in one cord use 400.5(A)(2).
| 12 AWG | 35 A | 40 A | 52 A | 25 A |
|---|---|---|---|---|
| 10 AWG | 50 A | 55 A | 68 A | 35 A |
| 8 AWG | 70 A | 80 A | 90 A | 50 A |
| 6 AWG | 95 A | 105 A | 120 A | 65 A |
| 4 AWG | 125 A | 140 A | 157 A | 85 A |
| 3 AWG | 145 A | 165 A | 182 A | 100 A |
| 2 AWG | 170 A | 190 A | 210 A | 115 A |
| 1 AWG | 195 A | 220 A | 244 A | 130 A |
| 1/0 AWG | 230 A | 260 A | 281 A | 150 A |
| 2/0 AWG | 265 A | 300 A | 325 A | 175 A |
| 3/0 AWG | 310 A | 350 A | 376 A | 200 A |
| 4/0 AWG | 360 A | 405 A | 436 A | 230 A |
| 250 kcmil | 405 A | 455 A | 485 A | 255 A |
| 262 kcmil | 417 A | 468 A | 496 A | 261 A |
| 313 kcmil | 468 A | 527 A | 562 A | 292 A |
| 350 kcmil | 505 A | 570 A | 600 A | 350 A at 90 °C |
| 444 kcmil | 577 A | 651 A | 701 A | 400 A at 90 °C |
| 500 kcmil | 620 A | 700 A | 749 A | 430 A at 90 °C |
| 535 kcmil | 643 A | 725 A | 770 A | 444 A at 90 °C |
| 646 kcmil | 716 A | 808 A | 867 A | 491 A at 90 °C |
| 750 kcmil | 785 A | 885 A | 954 A | 535 A at 90 °C |
Free-air values are for one conductor in air (Table 310.17 conditions); three in a raceway take the raceway column. Size 262, 313, 444, 535 and 646 kcmil are DLO-only sizes; Southwire interpolates them.
05 / Field guide
Portable power,
permanent rules.
SO, SOOW and SJOOW are flexible cords for portable equipment, sized by NEC Table 400.5(A)(1). DLO is a fine-stranded 2 kV cable from diesel locomotives that now carries generator and battery power; it is listed RHH/RHW-2, and its ampacity comes from the maker’s data (Southwire SPEC 45042).
DLO in the air and in a raceway
A single DLO conductor in free air carries far more than three in a raceway: 4/0 is 405 A at 90 °C in free air but 260 A as one of three; 2 AWG 190 A against 130 A. Terminations usually hold you to the 75 °C column.
Fine strands need the right lugs
DLO’s many fine strands need lugs listed for fine-stranded conductors (Class I or K); standard set-screw lugs can cut strands.
More than three current-carrying conductors
A multiconductor cord carrying more than three loaded conductors is derated like a raceway, by Table 400.5(A)(3): 4–6 conductors 80 %, 7–9 70 %, 10–20 50 %. A neutral that carries only the unbalanced current and the equipment ground do not count. Correct for ambient temperatures other than 30 °C with Table 310.15(B)(1).
SOOW or DLO?
SOOW is a jacketed multiconductor cord rated 600 V for portable tools, lights and equipment that moves; it is sized by Table 400.5(A)(1). DLO is a single conductor rated 2 kV, run one cable per phase, for generator tie-ins, temporary feeders and battery banks. DLO printed “for CT use” (as Southwire’s is) may also be installed in cable tray. Either way, terminations and the equipment listing decide the temperature column you may use.
DLO on battery banks and inverters
Fine-stranded DLO bends easily in tight battery boxes and inverter cabinets, which is why it has largely replaced welding cable there. Size it by the inverter’s maximum DC current and the run, and remember that in free air one 2 AWG conductor is rated 190 A at 90 °C, but terminations and enclosures usually hold it to the 75 °C column, and three in one raceway carry far less.
Questions
Answered plainly.
01What is the ampacity of 10/3 SOOW?
+−
25 A with three current-carrying conductors (a 3-phase or 120/240 V load), 30 A when only two carry current (a 120 V or 240 V load with a ground), by Table 400.5(A)(1).
02What does SOOW stand for?
+−
S: extra-hard service, O: oil-resistant jacket, O: oil-resistant insulation, W: weather and water resistant. SJOOW is the junior (300 V) version.
03What is DLO cable used for?
+−
Generator connections, battery banks, solar and EV infrastructure, stage power and other flexible high-current runs. It is listed RHH/RHW-2 at 2 kV.
04Is DLO ampacity in the NEC?
+−
Not under its own name. Listed as RHH/RHW-2 it can use Tables 310.16 and 310.17; Southwire publishes values for its DLO-only sizes (262, 313, 444, 535 and 646 kcmil).
05Can SO cord be used as permanent wiring?
+−
No. 400.12 bars flexible cord as a substitute for fixed wiring, through walls or ceilings, or concealed behind building surfaces.
06Is DLO the same as welding cable?
+−
Both are fine-stranded and flexible, but DLO is listed as RHH/RHW-2 building wire (2 kV) and can be used where the NEC calls for those types; welding cable is not listed for building wiring.
07Do I derate SOOW cord in a hot location?
+−
Yes. Apply the Table 310.15(B)(1) ambient factor for the cord’s temperature rating, and Table 400.5(A)(3) if more than three conductors carry current.