MC Cable vs NM-B (Romex): Comparison
MC Cable (Metal-Clad) vs NM-B (Romex)
| Feature | MC Cable (Metal-Clad) | NM-B (Romex) |
|---|---|---|
| Armor | Interlocked metal armor | Plastic jacket only |
| Ground path | Armor + internal ground | Internal ground wire only |
| Residential | Permitted everywhere | Permitted (1-3 family, dry) |
| Commercial | Permitted everywhere | Generally NOT permitted |
| Exposed runs | Permitted | Limited - must protect |
| Wet locations | MC-HL type only | NOT permitted |
| Fire rating | Higher - metal armor | Lower - plastic jacket |
| Cost (12/2) | $0.75-1.50/ft | $0.30-0.60/ft |
| NEC Article | 330 | 334 |
When to use MC Cable
MC (Metal-Clad) cable is essentially Romex with a metal armor jacket. It is permitted in almost every location and occupancy type, including commercial buildings where NM-B is prohibited. MC cable is increasingly popular for remodels because it can be fished through finished walls and its armor protects against accidental nail or screw penetration.
In jurisdictions like Chicago where NM-B is banned, MC cable is the standard residential wiring method. MC cable with an internal green insulated ground wire provides a redundant grounding path (armor + wire).
When to use NM-B
NM-B (Romex) is the most common residential wiring method in the United States. It is cheaper, lighter, and faster to install than MC cable. NM-B is permitted in 1- to 3-family dwellings, in dry locations, concealed in walls, floors, and ceilings.
It cannot be used in commercial buildings (generally), in wet or damp locations, exposed where subject to physical damage, or above suspended ceilings in commercial spaces. For standard residential new construction, NM-B is the clear winner on cost and speed.
On the job
A kitchen remodel adds three new circuits (dishwasher, microwave, receptacles). In existing finished walls, you are fishing cables through wall cavities you cannot see. MC cable is the safer choice here - if you hit a nail or screw while fishing, the metal armor protects the conductors.
With NM-B, that same nail could nick insulation and create a hidden short circuit or ground fault. The cost difference for three kitchen circuits (roughly 75 feet total) is about $35-70 in extra material for MC - well worth the added protection in a remodel.
Cost comparison
MC cable costs roughly 2-2.5x what NM-B costs for the same gauge. For a full new-construction home (30 circuits, 1,500 feet of cable), the difference is $650-1,300 in material. For a single circuit or a small remodel, the difference is $20-50 - usually not worth worrying about given the better protection.
InstallationInstallation difficulty
Rotary cutter needed. Anti-short bushings required.
Standard cable ripper. Familiar to most DIYers.
MC cable requires a special rotary cable cutter or MC cable cutter to strip the armor without damaging the conductors. NM-B strips with a standard cable ripper. Both use standard connectors at boxes, though MC uses specific anti-short bushings (red-head bushings) at each box entry.
MC cable is slightly harder to bend in tight spaces due to the armor, and it requires anti-short protection at every termination.
Related guides
External resourcesTrusted references
Frequently asked questions
Which is better, mc cable (metal-clad) or nm-b (romex)?
Neither is universally better - each has specific strengths for different situations. MC cable goes anywhere NM-B can, plus commercial, exposed, and some wet locations. NM-B wins on cost (roughly half the price). Use MC when code prohibits NM-B, when physical protection is needed, or in remodels where routing through finished walls is easier with MC's armor.
Can I use mc cable (metal-clad) and nm-b (romex) in the same installation?
Yes, many installations use both where each is best suited. Transition points must be properly connected per NEC requirements. Always ensure the transition is accessible and properly identified.
What does the NEC say about mc cable (metal-clad) vs nm-b (romex)?
The NEC specifies where each is permitted and prohibited. Check the specific NEC articles referenced in the comparison table above. Your local jurisdiction may have amendments that further restrict or modify these requirements.
Do I need a permit for this electrical work?
In most jurisdictions, any new circuit or wiring change requires a permit and inspection. Check our state-by-state permit guide for your specific requirements. Working without a permit can void insurance and create liability issues.
Can MC cable be used outdoors?
Standard MC cable is rated for dry locations only. MC-HL (Hospital Listing) or MC cable with a PVC jacket is rated for wet locations. Standard MC cable should not be used outdoors, underground, or in any wet or damp location unless it is specifically listed for that use. Always check the cable marking for the specific listing.
NEC 2023 references verified April 2026