Comparing cable types
MC vs AC cable: telling armored cable apart
MC and AC cable look similar from across the room: flexible metal armor with insulated conductors inside. The differences are in the armor, the bonding path and the fittings, and they matter to the next installer.
Both are 600-volt wiring methods used for branch circuits and feeders in commercial construction. Both are purchased as surplus, usually in coils rather than on reels.
The bonding difference
AC cable, often called BX, contains a bare aluminum bonding strip in contact with the armor, which makes the armor itself the equipment grounding path. MC cable carries a separate green insulated grounding conductor inside the armor, so the armor is not relied on for grounding.
That is why MC is the default in most modern commercial specifications, including hospital work, and why AC still appears in older buildings and in some residential applications.
What to look for on a coil
The armor print identifies the type and the conductors. Look for MC or metal-clad, AC or armored, the conductor size and count, and the voltage rating. A cut end shows whether there is a green ground conductor (MC) or a thin bare strip (AC).
| MC cable | AC cable | |
|---|---|---|
| Grounding | Separate insulated ground conductor | Bare bonding strip, armor is the ground path |
| Armor | Interlocked aluminum or steel | Interlocked steel, sometimes aluminum |
| Common uses | Commercial branch circuits, hospital work | Older commercial and residential branch circuits |
| Identification | Print reads MC; green ground at cut end | Print reads AC or BX; thin bare strip at cut end |
Questions about this
Can MC and AC be quoted together?
Yes, as separate lines. They are different products and are priced separately.
Does crushed armor ruin a coil?
Usually only the damaged section. Photograph the crush so we can judge how much usable length remains.
Is hospital-grade MC different?
Yes. It includes an insulated grounding conductor and is listed for health care facilities; the armor print states it.