Electrical Supplies…
Electrical Code…
A fabricated assembly of insulated conductors in a flexible interlocked metallic armor.
Construction: Type AC cable shall have an armor of flexible metal tape and shall have an internal bonding strip of copper or aluminum in intimate contact with the armor for its entire length.
Conductors: Insulated conductors shall be of a type listed in Table 310.104(A) or those identified for use in this cable. In addition, the conductors shall have an overall moisture-resistant and fire-retardant fibrous covering. For Type ACT, a moisture-resistant fibrous covering shall be required only on the individual conductors.
Equipment Grounding Conductor: Type AC cable shall provide an adequate path for fault current as required by 250.4(A)(5) or (B)(4) to act as an equipment grounding conductor.
Marking: The cable shall be marked in accordance with 310.120, except that Type AC shall have ready identification of the manufacturer by distinctive external markings on the cable armor throughout its entire length.
(National Electrical Code® 320.2, 320.100, 320.104, 320.108, 320.120)
NT Commentary…
Armored Cable, Type AC, also known as BX:
So there seems to be a bunch of confusion among many helpers, apprentices, and even licensed folks out there as to what constitutes the differences between AC Cable, MC Cable, Flexible Metal Conduit, and Flexible Metallic Tubing. If you are a serious electrical apprentice, the best advice I can give you is believe half of what you hear during coffee break and then look it up in YOUR CODE BOOK. The answers are all there and they are official.
Sure its a pain in the ass flipping through pages in that code book in a quest to find COMPLETE answers to questions. But I will tell you this… Doing so will familiarize you with that book and that will greatly benefit not only your technical knowledge but also your test score the day you sit down for your license exam.
Knowledge this! That most of the wiring material articles within Chapter 300 of the NEC have a definition within them for that item. The definition always fall in section xxx.2. In the case of AC Cable that would be 320.2. In the case of MC Cable it would be 330.2. In the case of Flexible Metal Conduit it is 348.2. Flexible Metallic Tubing is 360.2. Get it?
Also, each wiring material article has a Part III titled Construction Specifications. Most often Part III has within it a section xxx.100 Construction which contains the general construction specifications of the item and depending upon the item, one or more of the following sections: xxx.104 Conductors, xxx.108 Equipment Grounding Conductor, and xxx.120 Marking.
My point is that the NFPA strives to make the NEC consistent from article to article throughout the code book and if you learn the mechanics of these consistencies you will up your game on the job as well as on examination day.
Given all that, go ahead and look at the differences between AC, MC, FMC, and FMT in your code book. I’m not gonna do it for you here. That way there you can be confident and the truth monkey at break time.
(NT)