A 12/2 MC cable packs two 12 AWG current-carrying conductors plus a separate green ground inside interlocking aluminum armor.
The “2” counts current-carrying conductors only; the green ground rides outside that number — a detail that skews reel shopping and box-fill math. Inside the armor sit two 12 AWG insulated conductors, normally black and white, plus one 12 AWG green equipment grounding conductor. Electricians favor this cable on 20-amp branch circuits because it pulls faster than conduit and arrives with its ground built in.
What The 12/2 Count Includes
The “12” is the gauge and the “2” is the count of current-carrying conductors — phase conductors plus neutral — with the grounding conductor tallied separately.
Southwire’s Armorlite Type MC product listing spells it out: 12/2 is 12 AWG, two conductors, 600 V, THHN/THWN-2 insulated, grounded with a 1×12 ground. The count excludes the green ground, which is why a “2 conductor” label and a three-wire box never contradict each other.
- Gauge: both current-carrying conductors are 12 AWG copper — solid on one SKU, stranded on others.
- Color: the 120/208 V sets run black and white for the live pair, green for ground.
- Circuit fit: 12 AWG copper suits a 20-amp breaker on a standard branch circuit.
A 12/3 MC cable adds a third current-carrying conductor for two switched legs or a shared neutral, and still carries a green ground. Counting the ground as part of the “2” is the most common mix-up; a reel labeled 12/2 labels only what carries current. Type MC earns its keep in commercial work, exposed runs, and spots where plastic-sheathed cable wouldn’t survive, with NEC Article 330 setting permitted uses.
Does 12/2 MC Cable Carry Its Own Ground?
Yes — every 12/2 MC construction in the manufacturer listings includes a separate insulated grounding conductor, green in the 120/208 V color sets.
It’s a full 12 AWG wire, sized to match the current-carrying pair rather than a reduced jumper. The interlocking aluminum armor handles mechanical protection: the armor is shielding, the green wire is the ground path. Because the ground ships inside, there’s no separate conductor to pull. Termination still needs the right MC connector and a bonded metal box, where the green conductor bonds the enclosure before landing on the device’s ground screw. Where the ground is missing or cut short, the circuit loses its fault path — a code problem, not a convenience one.
Specs: What Varies Between Products
Outside diameter and conductor type are where 12/2 MC products diverge — one armored construction measures roughly 0.487 to 0.495 in across, while a PVC-jacketed version runs about 0.593 in.
| Spec | What 12/2 MC Listings Show |
|---|---|
| Current-carrying conductors | Two, at 12 AWG |
| Ground | One 12 AWG green, counted separately |
| Armor | Interlocking aluminum strip |
| Insulation | THHN/THWN-2 on Armorlite constructions |
| Voltage rating | 600 V |
| Temperature rating | 90°C dry |
| Outside diameter | About 0.487–0.495 in bare; roughly 0.593 in with PVC jacket |
| Weight | 110 lb per 1,000 ft on one listing |
| Conductor metal | Solid copper on one SKU, stranded on others |
| Listings | UL 83, 1479, 1569, 1581, 2556; files E80042 and R-14141 |
Two ratings hold across every listing reviewed: 600 V and 90°C dry. Those are product limits, and installation conditions follow the specific listing plus NEC Article 330. Cerrowire’s MC cable spec sheet documents the same construction pattern across its Type MC line. Jacketed and unjacketed versions both exist: the bare Armorlite runs slimmer and lighter for tight stud bays; the PVC-jacketed version adds an outer layer where corrosion resistance or a tougher surface is wanted. Reel pricing tracks copper, so buy against a fresh listing. Our tested 12/2 MC cable picks cover which reels hold up.
Three checks settle most purchases:
- Confirm the SKU ships a grounding conductor.
- Match conductor count to the circuit, not the wires you’d like.
- Stay inside the 600 V and 90°C dry ratings, and check the listing before any damp or outdoor run.
FAQs
Is 12/2 MC cable the same thing as 12/2 Romex?
No. Romex is plastic-sheathed nonmetallic cable, covered by its own NEC article and intended for dry, protected indoor locations. MC cable uses interlocking aluminum armor and ships with an insulated green ground. Both may use 12 AWG copper conductors, but outer construction, permitted locations, and physical toughness differ enough that they aren’t interchangeable.
How many wires sit inside a 12/2 MC cable?
Three conductors total: two 12 AWG current-carrying conductors plus one 12 AWG green equipment grounding conductor. The “12/2” label counts only the current-carrying pair, so the total head count runs one higher than the reel name suggests.
Can 12/2 MC cable be used in wet or outdoor locations?
Standard 12/2 MC constructions reviewed here are listed 600 V and 90°C dry, so a damp or wet run needs a cable specifically listed for that environment — often a jacketed Type MC product. Check the individual listing and applicable NEC article; installation conditions follow the product listing in hand.
References & Sources
- Southwire. “Armorlite Type MC Cable, THHN/THWN, 120/208V Colors.” Source for conductor count, 12 AWG sizing, 600 V rating, THHN/THWN-2 insulation, and the 1×12 ground.
- Cerrowire. “MC Cable Specifications.” Documents Type MC construction details, ratings, and listing data across the product line.