Metal Clad Cable 101: Definition, Types, Cost & Installation Guide

A commercial electrician can save 30% on installation time by choosing metal clad cable over rigid conduit. That number comes from real-world project data, not a lab simulation. MC cable eliminates the separate step of pulling wires through conduit, and its flexible armor speeds up routing through studs and joists. This guide breaks down what metal clad cable actually is, how it stacks up against alternatives, and the precise steps to install it without triggering a code violation.

What Is Metal Clad Cable?

Metal clad cable is a factory-assembled wiring solution that bundles insulated conductors, a full-size equipment grounding conductor, and a protective metal armor in one package. Unlike older BX cable, which relied on the armor itself as the ground path, MC cable includes a dedicated green ground wire that runs alongside the circuit conductors. That one detail eliminates decades of grounding reliability headaches.

The armor typically comes in two forms: interlocking aluminum strip (the most common flexible type) and continuously corrugated welded aluminum (for wet locations or direct burial). Inside, you’ll find copper or aluminum conductors rated for 600 volts, wrapped in THHN or XHHW insulation. The entire assembly arrives on a reel ready to cut, strip, and connect. No conduit threading, no separate wire pulls.

Key components of every MC cable:

• One or more phase conductors (copper or aluminum, 14 AWG and larger)
• A full-size equipment grounding conductor (green insulation)
• Flexible aluminum armor—either interlocked strip or continuous corrugated weld
• Aplastic inner wrap that protects conductors during installation

MC Cable vs. Other Wiring Options: A Cost & Performance Comparison

Contractors often weigh MC cable against Romex (NM-B), flexible metal conduit (FMC), and rigid conduit. The right choice hinges on the environment, the local code, and the labor equation. The table below gives you decision-relevant numbers, but the short version is this: MC cable wins in commercial and industrial settings where physical protection matters and labor cost dominates.

Purely on material cost, Romex looks cheaper. But in a commercial building where the code mandates metal protection, Romex isn’t an option. MC cable gives you that code-mandated armor for roughly half the installed cost of rigid conduit, thanks to faster handling. Its aluminum armor also weighs significantly less than steel conduit, reducing fatigue on a crew running hundreds of feet overhead.

Common Sizes and Specifications of MC Cable

Selecting the right gauge and conductor type is where many circuit designs stumble. The table below provides the baseline ampacities for common MC cable sizes at 60°C and 75°C insulation ratings, based on NEC Table 310.16. Always verify your termination temperature limits before finalizing the conductor size.

Aluminum conductors offer weight and cost advantages but require upsizing by two AWG sizes for equivalent ampacity. For example, a 12 AWG aluminum conductor at 60°C carries only 15 amps—same as copper 14 AWG. Always confirm the listing on the cable jacket; MC cable marked “AL” uses aluminum conductors. Reputable manufacturers, including Jiangsu Dongfeng Cable Co., Ltd., supply both copper and aluminum options with full UL test documentation.

Step-by-Step Installation Guide for MC Cable

Installing MC cable without damaging the conductors or violating code takes three disciplined steps. If you rush the armor removal or skip the anti-short bushing, you risk an immediate inspection failure.

1. Cut the armor cleanly. Use a rotary armored cable cutter for consistent results without nicking the inner wires. If using a hacksaw, make a shallow ring cut at 90 degrees and stop the moment you score through the armor. Never cut all the way through both armor and conductors in one pass.
2. Strip and protect. Remove 8–10 inches of armor to give yourself working length. Slide an anti-short plastic bushing (often red in color) over the cut end of the armor to insulate the sharp edge from the conductors. This step is non-negotiable per NEC 330.40.
3. Connect and ground. Insert the prepared cable end into a listed MC cable connector on a steel junction box. Tighten the connector’s clamping mechanism until it bites into the armor securely. Connect the green ground wire to the box’s grounding screw, then terminate the circuit conductors.

Key Compliance and Safety Standards (NEC & UL)

MC cable installation must follow NEC Article 330. Key permitted uses include:

• Exposed or concealed dry locations (330.10(A))
• Wet locations, provided the outer sheath and connectors are rated for moisture (330.10(A)(2))
• Hazardous locations, with specific cable types marked “MC-HL” for Class I, Division 1 areas (330.10(C))

UL 1569 governs the manufacturing requirements: minimum armor thickness, pull-out resistance of the connectors, and flame propagation limits. A compliant cable will carry the “UL Listed” mark and a rated voltage of 600V. Northeast contractors working under Boston or Chicago codes should confirm local amendments—some jurisdictions still restrict MC cable below 7 feet in certain occupancies, despite the NEC allowance.

Common Mistakes When Working with MC Cable (and How to Avoid Them)

Even experienced electricians trip over these three errors. The fixes are simple but mandatory.

• Using a plastic junction box. MC cable armor and connectors require a metallic box to maintain the ground path integrity. Plastic boxes fail inspection immediately. Solution: specify steel 4-square or octagonal boxes for every MC termination.
• Forgetting the anti-short bushing. The cut aluminum armor edge will abrade Phase conductors over time. Solution: install the supplied red plastic bushing on every single cable end, full stop.
• Overbending the cable. Bending radius below 7 times the overall cable diameter deforms the armor and can crack the internal insulation. Solution: maintain gentle sweeps and use pre-manufactured 90-degree connectors where tight turns are unavoidable.

Where to Buy Metal Clad Cable: Tips for Contractors and Engineers

Pricing on MC cable tracks the LME copper index closely. When copper spot prices spike, locked-in bid pricing from a manufacturer becomes critical for project margins. Look for suppliers that publish UL certificates online and offer custom reels or pre-cut lengths to reduce jobsite waste. Jiangsu Dongfeng Cable Co., Ltd. provides a full range of MC cable with aluminum interlocked armor and copper conductors, backed by a UL-certified quality system—request a quote or download the technical catalog directly from their product page. For bulk orders, confirm lead times and verify that the UL file number covers the exact conductor configuration you need.