MC CABLE, AC/BX, TRAY CABLE AND TC-ER, BOUGHT BY THE FOOT

Two Armored Families: MC and AC

MC is Metal-Clad cable, Article 330. The armor is interlocked metal tape, steel or aluminum, or a smooth continuous corrugated aluminum tube. Conductors inside are THHN, THWN or XHHW and the assembly is rated 600 volts unless marked otherwise. Most constructions carry a green equipment grounding conductor, and the armor serves as the ground only where the cable is listed for that use.

AC is Armored Cable, Article 320, and the trade still says BX. It looks similar and is not the same product. AC has a bare aluminum bonding strip in contact with the inside of the armor, and that strip is what makes the armor a dependable fault path. There is usually no green conductor inside. A coil of AC priced as MC, or the reverse, is a mistake worth catching before the number goes out.

• MC: interlocked steel or aluminum armor, or corrugated aluminum, with a green ground in most types.
• MC-HCF: health care facility MC with a redundant ground path, common in hospitals and clinics.
• MC-PCS: power and control signal conductors under one armor, used for lighting control runs.
• AC: interlocked armor with a bonding strip, commonly 14/2, 12/2, 12/3, 10/3 and 8/3.
• Sizes 14 AWG through 4/0, two to four conductors, in 250 and 1,000 foot coils.

Tray Cable and the ER Suffix

Tray cable is Type TC, Article 336: a factory assembly of two or more insulated conductors, twisted or parallel, with or without a ground, jacketed for cable tray, raceway or, where marked, direct burial. The ordinary construction is 600 volts and heavier builds reach 2 kV. Sunlight resistance is normal rather than exceptional.

TC-ER adds exposed run. An ER cable may leave the tray and travel to equipment without conduit, unsupported for up to six feet where the Code allows it, because it passes crush and impact tests that plain TC does not. That suffix is worth money on a reel. A 1,000-foot length of TC-ER is not interchangeable with plain TC, and only the print will settle which one you have.

VFD, PLTC and the Shielded Variants

VFD cable is not an NEC cable type. It is a manufactured assembly, usually listed as TC or MC, built with three symmetrical phase conductors, a copper tape or braided shield and three grounds, in 600 volt and 1 kV versions. The shield and the symmetry exist to control what a drive does to a motor lead at high switching frequency.

PLTC is power-limited tray cable under Article 725: 300 volts, 20 to 16 AWG, for Class 2 and Class 3 circuits in tray. ITC is instrumentation tray cable at 300 volts. Both are small, both are commonly left in part coils, and both are identified by print rather than by appearance.

• VFD: 16 AWG to 4/0, shielded, 600 V or 1 kV, usually a black or orange jacket.
• Armored VFD: corrugated aluminum or interlocked armor over the shielded core.
• Continuous flex VFD for cable carriers and moving equipment, with a higher strand count.
• PLTC: 300 V, 20-16 AWG, two to twenty-four conductors, tray rated.
• ITC: 300 V instrumentation pairs or triads with an overall shield.

Coils, Remnants and What a Length Is Worth

Length matters here more than in building wire, because tray and MC jobs are measured in feet and the leftover is often short. Fifteen feet of 12/3 MC is a real item. Forty feet of 4/0 TC-ER is a better one. A coil under ten feet rarely justifies a collection on its own.

Remnants are priced as footage, not as scrap. The exception is a coil so short or so damaged that the copper is the only value left, and we will say so plainly rather than dress it up as something it is not. Coil it, tape the ends and write the length on a tag before it goes on the truck.

Photograph the Print, Then the Tag

The armor print carries the type, the voltage and the conductor count, and on MC it also carries the grounding statement. Photograph it where it lies, then photograph the tag at the end of the coil. A cut end photograph settles conductor count, colors and whether a green ground is present.

Cable is the only thing we price. Switchgear, transformers, breakers, motor control centers, generators, chillers and machinery are not bought, though they often share a room with the cable. Cable that is not tray rated belongs on the control and instrumentation page, and armored feeder or service cable belongs with SER, SEU and URD. The quote form takes whichever applies.

• The print on the armor or jacket, unrolled flat and legible.
• The reel or coil tag, with footage visible.
• A cut end showing conductor count, colors and the ground conductor.
• The armor style: interlocked, corrugated or smooth aluminum.
• The jacket condition at the coil end, where water enters first.