SOOW Cord Ampacity Chart
Allowable ampacity for SOOW, SJOOW, and other flexible cords by gauge, per NEC Table 400.5(A)(1), with the adjustment factors for cords that have more than three current-carrying conductors. Covers the full SOOW range from 18 AWG to 2 AWG.
SOOW Ampacity by Gauge (NEC Table 400.5(A)(1), 30°C Ambient)
| Conductor Size | 2 Current-Carrying Conductors (Column B)* | 3 Current-Carrying Conductors (Column A)* | Typical Use |
|---|---|---|---|
| 18 AWG | 10 A | 7 A | Light-duty tools, controls, signal |
| 16 AWG | 13 A | 10 A | Small tools, lighting, pendant controls |
| 14 AWG | 18 A | 15 A | 15 A tool and equipment cords |
| 12 AWG | 25 A | 20 A | 20 A circuits, compressors, pumps |
| 10 AWG | 30 A | 25 A | 30 A circuits, RV and welder leads, small motors |
| 8 AWG | 40 A | 35 A | Generator feeds, motors to ~10 HP |
| 6 AWG | 55 A | 45 A | 50 A generator and spider box feeds |
| 4 AWG | 70 A | 60 A | 60 A three-phase equipment |
| 2 AWG | 95 A | 80 A | Largest SOOW; temporary power distribution |
*Allowable ampacity per NFPA 70 (NEC) Table 400.5(A)(1) for copper conductors in flexible cords and cables at 30°C (86°F) ambient. Column B applies when only two conductors carry current (single-phase hot/neutral or hot/hot); Column A applies when three conductors carry current (three-phase, or single-phase with a neutral carrying harmonic current). The equipment grounding conductor never counts. Cord is rated 60°C unless marked otherwise; SOOW is marked 90°C. Confirm against the NEC edition your jurisdiction enforces. This chart is for reference only; consult a licensed electrical engineer for your installation.
Adjustment for 4 or More Current-Carrying Conductors (NEC 400.5(A)(3))
| Current-Carrying Conductors | Multiply the Column A Value By | Example: 12 AWG (20 A base) |
|---|---|---|
| 4 to 6 | 0.80 | 16 A |
| 7 to 9 | 0.70 | 14 A |
| 10 to 20 | 0.50 | 10 A |
| 21 to 30 | 0.45 | 9 A |
| 31 to 40 | 0.40 | 8 A |
| 41 and above | 0.35 | 7 A |
This is why a 5-conductor 8 AWG SOOW feeding a three-phase load with a loaded neutral (four current-carrying conductors) is rated 28 A, not 35 A. Multi-conductor control cords (12/C, 16/C, 37/C) are usually sized for signal current, not power, so the derate rarely matters there.
Ambient Temperature Correction
Table 400.5(A)(1) assumes 30°C (86°F) ambient. For hotter locations, multiply by the NEC Table 310.15(B)(1) correction factor for a 90°C conductor: about 0.96 at 35°C, 0.91 at 40°C, 0.87 at 45°C, and 0.82 at 50°C. Cords run across hot asphalt, inside engine compartments, or in direct summer sun routinely see 40°C or more.
How to Pick a SOOW Cord Size
- Find the load current. Use the nameplate amps for tools and equipment, or NEC Table 430.248/430.250 full-load current for motors. For continuous loads, multiply by 1.25.
- Count current-carrying conductors. Hot + neutral (120V) or hot + hot (240V single-phase) = 2. Three hots (three-phase) = 3. Add the neutral as a fourth only if it carries harmonic or unbalanced current. Ground never counts.
- Read the table. Use Column B for 2 CCC or Column A for 3 CCC, and pick the first gauge that meets or exceeds the load. Apply the adjustment factor if you have 4 or more CCC.
- Choose the conductor count. A 240V single-phase load with ground is 3/C (12/3, 10/3); three-phase with ground is 4/C (8/4, 6/4); three-phase with neutral and ground is 5/C (8/5, 6/5).
- Check voltage drop on long runs with the wire size calculator. A 100 ft 12 AWG cord at 20 A on 120V drops about 6.5V, which is past the 5% rule of thumb; step up to 10 AWG.
Quick Picks
| Load | Single-Phase + Ground (2 CCC) | Three-Phase + Ground (3 CCC) |
|---|---|---|
| 15 A | 14/3 SOOW | 14/4 SOOW |
| 20 A | 12/3 SOOW | 12/4 SOOW |
| 30 A | 10/3 SOOW | 8/4 SOOW |
| 40 A | 8/3 SOOW | 6/4 SOOW |
| 50 A | 6/3 SOOW | 4/4 SOOW |
| 60 A | 4/3 SOOW | 4/4 SOOW |
| 80 A | 2/3 SOOW | 2/4 SOOW |
| 100 A and up | Beyond SOOW: use Type W or DLO portable power cable | |
What Is SOOW Cord?
SOOW is 600V hard-service portable cord: S for service (hard usage), OO for oil-resistant insulation and oil-resistant jacket, and W for weather and water resistance. It uses fine-stranded bare copper conductors, EPR thermoset insulation, and a heavy CPE thermoset jacket rated −40°C to +90°C. It is UL 62 and CSA C22.2 No. 49 listed and MSHA approved, and NEC Article 400 permits it for pendants, portable tools and equipment, and connections to stationary equipment where flexibility or frequent interchange is needed. SJOOW is the 300V junior-service version, and SEOOW / STOOW substitute TPE or PVC-based jackets. See our portable cord letters guide for the full decoder.
Frequently Asked Questions
How many amps can 12/3 SOOW carry?
25 A when two conductors carry current (single-phase plus ground) or 20 A three-phase. The ground does not count.
How many amps is 10 gauge SOOW good for?
30 A with two current-carrying conductors, 25 A with three.
What size SOOW do I need for 50 amps?
6 AWG for single-phase (55 A), 4 AWG for three-phase (60 A). Size at 125% if the load is continuous.
Is SOOW rated for 90°C or 60°C?
SOOW is marked 90°C, but Table 400.5(A)(1) does not give a higher ampacity for it. The rating buys you margin in hot ambients, not more amps.
Can I use SOOW instead of SJOOW?
Yes. SOOW is 600V hard service and can replace 300V SJOOW anywhere the extra jacket thickness fits the strain relief. The reverse is not true.
