Cable types

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jaylectricity

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Massachusetts
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licensed journeyman electrician
Doing mostly residential work I am used to using NM and SE but haven't used much else. My old boss and I wired a beauty spa with MC one year and I'm familiar with EMT and PVC piping.

My old boss usually referred to MC as BX. I don't see BX in the code book, so I'm wondering where that came from. Also I'm having trouble seing the difference between MC and AC.

Any help?
 

JohnJ0906

Senior Member
Location
Baltimore, MD
Usually, I hear people (me too) call type AC cable "BX", kind of like calling MN-B "romex". AC typically has no EGC, just the bondstrip-and-cable armor. MC has a EGC, and the armor isn't suitable for grounding.

I'm not sure where "BX" came from. Brand name like "romex"?
 

stickboy1375

Senior Member
Location
Litchfield, CT
jaylectricity said:
My old boss usually referred to MC as BX. I don't see BX in the code book, so I'm wondering where that came from. Also I'm having trouble seing the difference between MC and AC.

Any help?


Basic armored cable was developed in the early 1900s by Edwin Greenfield and Gus Johnson, who called their product BX cable. It has become a generic term for all armored cable. Some of the prevailing attitudes about the product most likely stem from imperfections inherent in the original BX.

bx-02cw.jpg

Today's BX and MC cable vs vintage BX Cable
 
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jaylectricity

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Location
Massachusetts
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licensed journeyman electrician
Yes, I remember him referring to the BX as Greenfield too, so that explains that. Thanks for the clarification.

Now why use MC with an extra full conductor for the EGC when it would be easier (and seemingly less expensive) to use AC?
 

infinity

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Location
New Jersey
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Journeyman Electrician
JohnJ0906 said:
Why 2 separate articles? 320 Armored Cable type AC and 330 Metal-Clad Cable type MC?
MC is not AC

Why two separate Articles? For one thing the support and securing provisions are different. MC can be used in thermal insulation at 75 degrees C, AC cable is only available up to I believe #2 conductors. MC is available in much larger sizes. I'm sure that there are other difference too. Hence two separate articles.
 

JohnJ0906

Senior Member
Location
Baltimore, MD
To be honest, I was responding to Stickboy's claim that AC and MC was the same. Since they are different cable types, they have seperate articles.
 

jaylectricity

Senior Member
Location
Massachusetts
Occupation
licensed journeyman electrician
Trevor and John...both of you seemed to ask yourself a question "Why two separate articles?" and then both of you went on to explain why. Where did that question come from?
 

stickboy1375

Senior Member
Location
Litchfield, CT
jaylectricity said:
Yes, I remember him referring to the BX as Greenfield too, so that explains that. Thanks for the clarification.

Now why use MC with an extra full conductor for the EGC when it would be easier (and seemingly less expensive) to use AC?

I myself would much rather see a grounding conductor, but thats just me.
 

infinity

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jaylectricity said:
Trevor and John...both of you seemed to ask yourself a question "Why two separate articles?" and then both of you went on to explain why. Where did that question come from?


Because he said this:


JohnJ0906 said:
Why 2 seperate articles? 320 Armored Cable type AC and 330 Metal-Clad Cable type MC?
MC is not AC
 

JohnJ0906

Senior Member
Location
Baltimore, MD
Stickboy had originally stated that AC and MC were the same. (He edited it out :D ). I intended my question to be rhetorical.

Seems your old boss was mixing his nicknames!:D
 

jaylectricity

Senior Member
Location
Massachusetts
Occupation
licensed journeyman electrician
JohnJ0906 said:
Stickboy had originally stated that AC and MC were the same. (He edited it out :D ) . I intended my question to be rhetorical.

Seems your old boss was mixing his nicknames!:D

Haha! OK, now I get it... and of course that explains your answer too Trevor.
 

stickboy1375

Senior Member
Location
Litchfield, CT
JohnJ0906 said:
Stickboy had originally stated that AC and MC were the same. (He edited it out :D ). I intended my question to be rhetorical.

Seems your old boss was mixing his nicknames!:D

I guess I wasn't quick enough.... I saw the problem after I posted, and deleted it before I read your post... After reading the definitions in the code, I'm still not sure I know what the difference is, I only buy MC type cable...
 
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jaylectricity

Senior Member
Location
Massachusetts
Occupation
licensed journeyman electrician
stickboy1375 said:
I guess I wasn't quick enough.... I saw the problem after I posted, but before you posted.

Haha, oh well...

Anyway, I agree that I want the full EGC, but I was just posing the question as a Devil's Advocate.
 

infinity

Moderator
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Location
New Jersey
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Journeyman Electrician
Confusion abounds when someone goes back and edits their post after it been read by others. A new post with the changes would be more in line with Mike Holt's Forum decorum.
 

stickboy1375

Senior Member
Location
Litchfield, CT
The weird thing is, I edited right after I posted it, it took me about 8 seconds, but it was too late... :grin: Its amaing how many posts can be put up while your typing...
 

jaylectricity

Senior Member
Location
Massachusetts
Occupation
licensed journeyman electrician
stickboy1375 said:
The weird thing is, I edited right after I posted it, it took me about 8 seconds, but it was too late... :grin: Its amaing how many posts can be put up while your typing...

That and once somebody opens the page your post is on, it is already loaded into their computer until they refresh the page or navigate away. So if somebody clicks on the topic in those 8 seconds, they won't see your changes.
 
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