10/4 wire is 10-gauge cable with four conductors inside one jacket; the 10 sets the wire size and the 4 counts the conductors.
For the full breakdown, see our best 10/4 Wire guide.
Two cables can sit side by side on the same shelf, both made of 10-gauge copper, and still belong on different jobs. The difference hides in one digit after the slash.
Sorting out what is 10/4 wire and how it differs from 10/3 and 10/2 lands on conductor count rather than gauge size. Every cable in the family uses 10 AWG copper. The number after the slash says how many conductors are bundled inside the jacket, which is why three cables that look nearly identical can suit three different circuits.
What The Numbers In 10/2, 10/3, And 10/4 Mean On A Cable Label
The number before the slash is the wire size, and the number after it counts the conductors in the cable.
Southwire sells the two-conductor version as 250 ft. 10/2 Solid Romex SIMpull CU NM-B W/G Wire, and the Home Depot listing describes it as #10 AWG residential wiring for outlets, switches and other loads. The same naming pattern carries to 10/3, listed as 100 ft. 10/3 Solid Romex SIMpull CU NM-B W/G Wire Pink Coil. The W/G stands for with ground, the bare conductor that rides along in NM-B cable and stays out of the slash count.
In a cord like SOOW, all four conductors are insulated and one of them normally serves as the equipment ground, a different arrangement from NM-B. Greater Wire lists 10/2, 10/3, and 10/4 MC cable as 10 AWG cable with two, three, or four cores, the same rule phrased around cores instead of conductors. The copper itself never changes: 10 AWG measures about 0.102 in across in all three.
Coil length rides at the front of the name, so a 250 ft. coil of 10/2 and a 100 ft. coil of 10/3 are sold by the same convention. Nothing in the fraction describes length.
The three versions line up this way:
| Cable Type | Conductors Inside | Jacket Diameter (MC) |
|---|---|---|
| 10/2 | Two insulated, plus a bare ground in NM-B | 0.631 in |
| 10/3 | Three insulated, plus a bare ground in NM-B | 0.735 in |
| 10/4 | Four, all insulated in cord and whip products | 0.784 in |
10/4 is the outlier in retail listings, showing up mostly as flexible cord or a liquid-tight whip — Southwire 10/4 SOOW Electrical Wire and Southwire 10/4 Liquid Tight 2M Non-Metallic Whip — rather than as standard in-wall NM-B. Same 10 AWG copper, one extra conductor, and a different product family.
Does 10/4 Wire Carry More Current Than 10/3?
No. The extra conductor adds a path, not capacity. Ampacity follows the 10 AWG size, the insulation, and the circuit design, not the count after the slash.
The 4 is easy to misread as more power. What changes is what the cable was built to do.
