MC/BX/AC, please clarify. Also, what cut and bush do you use?

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darekelec

Senior Member
Location
nyc
Aluminum jacket BX (AC cable) is popular now around here. It is light. Its jacket prover Ofer a decade so it does not separate when pulled.
BX connectors have to be designed for AL tho. Many guys use set screw bx connectors which bothered me but then I saw set screw connector listed for AL jacket.
 
electrofelon

electrofelon

Senior Member
Location
Cherry Valley NY, Seattle, WA
darekelec said:
Aluminum jacket BX (AC cable) is popular now around here. It is light. Its jacket prover Ofer a decade so it does not separate when pulled.
BX connectors have to be designed for AL tho. Many guys use set screw bx connectors which bothered me but then I saw set screw connector listed for AL jacket.
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I should have said in post #18 that yes AC Is in the same category as MCAP as far as not having a wire EGC to terminate. Around here AC is so rare, most people don't even know it's a thing and will say something like "you mean bx? No you can't get that anymore".

Curious, how does the cost of AC compare to 12/2 MC where you are?
 
F

fastline

Senior Member
Location
midwest usa
Occupation
Engineer
Does anyone have any docs or vids on terminating MCAP? It's pretty interesting, though I will admit even MCAP would make me less confident in the EGC just due to the flimsy nature of MC. Give it a little tug and the cable splays out in a mile of sharp edges.

As for the bushings and connectors, I honestly haven't done enough of it to even cite the brand or type of connectors, but I do know they had a hard inner corner, no radius, and just trying to turn wire 90* in a panel was asking for it. Never such issues with NM.

The split bushings (red heads) are a JOKE! The split is exactly where wire will go, and right to a sharp metal edge of the MC. The clad is thin, there is no way to "remove the bur". The bushings never stay in place, and I could design something in 20min that is better, but I also think I am not the only guy that has run into this. Maybe better products exist.
 
D

darekelec

Senior Member
Location
nyc
electrofelon said:
I should have said in post #18 that yes AC Is in the same category as MCAP as far as not having a wire EGC to terminate. Around here AC is so rare, most people don't even know it's a thing and will say something like "you mean bx? No you can't get that anymore".

Curious, how does the cost of AC compare to 12/2 MC where you are?
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Curious, how does the cost of AC compare to 12/2 MC where you are?

I called the most reputable supply in 5 Boris of nyc now and he said same price for any 250’ roll. I am surprised as well. Bx, mc steel or aluminum jacket 1$ difference . 160$ per 250’ roll.

Right after pandemic I know there was a difference between steel and aluminum jackets.
 
LarryFine

LarryFine

Master Electrician Electric Contractor Richmond VA
Location
Henrico County, VA
Occupation
Electrical Contractor
fastline said:
The split bushings (red heads) are a JOKE! The split is exactly where wire will go, and right to a sharp metal edge of the MC. The clad is thin, there is no way to "remove the bur". The bushings never stay in place, and I could design something in 20min that is better, but I also think I am not the only guy that has run into this. Maybe better products exist.
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I have never had those problems. The chosen bushings should be large enough that the ends overlap when pushed into the sheath, and turned so the split is 180 deg. from the cut ends of the metal.

And I have no trouble re-shaping the cut ends of the sheath so there is no sharp edge against the wires even without a bushing. I use bushings with AC/BX and FMC, but not with MC, with its plastic liner.
 
electrofelon

electrofelon

Senior Member
Location
Cherry Valley NY, Seattle, WA
fastline said:
The split bushings (red heads) are a JOKE! The split is exactly where wire will go, and right to a sharp metal edge of the MC. The clad is thin, there is no way to "remove the bur". The bushings never stay in place, and I could design something in 20min that is better, but I also think I am not the only guy that has run into this. Maybe better products exist.
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I have also not had those problems. The connector should retain the redhead. Maybe you were using the wrong connectors?
 
hbiss

hbiss

EC, Westchester, New York NEC: 2014
Location
Hawthorne, New York NEC: 2014
Occupation
EC
electrofelon said:
Well you need an EGC. How would one provide and EGC without using a wire for NM? If the sheath is metallic, why not make that the EGC? Seems like a waste to provide a wire, not only for material cost but then more labor of terminating it.
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MC, with its separate insulated EGC was developed to be an armored cable that does away with the problems of the connectors and armor being used to provide EGC continuity like AC does. It is bullet proof. But I guess after some time, the guys who used AC and were switched to MC got annoyed with having to deal with another conductor, so some MC was watered down to again use the armor and connectors for the EGC. Why bother? Just use AC to begin with.

-Hal
 
electrofelon

electrofelon

Senior Member
Location
Cherry Valley NY, Seattle, WA
hbiss said:
Uggh! How about the manufacturer recommended Roto-Split? Sure, maybe a bit more work but you get a clean armor cut because it cuts with a saw blade at the proper angle.

-Hal
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The 1104's make a real nice cut, much better than dykes.
hbiss said:
MC, with its separate insulated EGC was developed to be an armored cable that does away with the problems of the connectors and armor being used to provide EGC continuity like AC does.
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. Oh? Just like all the "problems" there have been with using EMT as an EGC? I don't think there have been any problems with either it's just the grounding obsession cult

the guys who used AC and were switched to MC got annoyed with having to deal with another conductor, so some MC was watered down to again use the armor and connectors for the EGC. Why bother? Just use AC to begin with.
Click to expand...

Yeah I don't really see what niche MCAP is supposed to fill. Isn't that what AC is for? It does have a much bigger bonding strips/conductor so maybe it has a lower impedance fault path.
 
F

fastline

Senior Member
Location
midwest usa
Occupation
Engineer
All I can say is if we are connecting sensitive gear, we never just rely on the raceway as a low impedance ground path. Not really from a personnel safety perspective, but equipment.

As for cutting MC, as mentioned, I have not used it enough to be a 'pro MC guy', but I quickly adapted to my electric dotco. In manufacturing, I lived with one in my hand so I can deliver surgical precision with that. At least, IMO, better than that roto thing. I cut at an angle.
 
Jraef

Jraef

Moderator, OTD
Staff member
Location
San Francisco Bay Area, CA, USA
Occupation
Electrical Engineer
BX is actually a brand name for the first commercially available AC when it came out around 1910. It was made by a company called Sprague Electric, who was experimenting with two new methods of making a type of cable with armor on it, instead of using K&T. The “X” meant “Experimental” and they made two versions; A and B, but only BX was released to the market. Sprague Electric was bought shortly thereafter by GE, who trademarked the term “BX” as their brand of Armored Cable or “AC” as it later became known generically. So BX and AC are the same thing.

I think that Southwire now owns the trade name “BX”, just like they own the term “Romex” for NM cable.
 
G

gene6

Senior Member
Location
NY
Occupation
Electrician
Years ago I was in a old basement doing some troubleshooting of a burning electrical smell when my flashlight died, only then in the dark did I notice a slight orange glow to some BX cable in the corner. The cable was faulted and glowing slightly, breaker never tripped.
 
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