Correct way to extend BX cable

R

Rob2025

Member
Location
Toronto, Canada
Occupation
Electrician
Hello

As I had to move my light fixture to another location by few feet in the garage, I need to connect another BX cable to extend the length so it will reach to the light fixture at the new location.

Can I just connect the wires using marrettes, tape OR use marrettes, tape and place it in a metal enclosure box?
What's the appropriate method following Electrical codes to make such an extension?
 
Never heard of a Marrette but found out its what Canadians call a pressure connector ( ya wire nut ) . Do not forget to use the red anti short bushings that come with every 250'coil of type AC ( ya BX ) cable. I was taught to cut armored jacket at a 45 degree angle even if you use a Roto spilt tool. We usually wrap the flimsy 18 gauge bare wire back around BX jacket.
 
winnie said:
Marrette wire connector, invented by William P. Marr in Ontario. You can still buy connectors of the set screw design that he first came up with.
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Back in the 1970's somebody gave me a box of similar connectors think made by Ideal. They had a brass fitting with a screw that you tighten to secure wires . brass fitting external threads to screw on a black what looked like a regular wire nut. After collecting dust in my garage for over 40 years I trashed them.
 
winnie said:
You are talking about these:

High Temperature Twist-on Wire Splicing Connectors 22-10 Gauge Wire, Three 14 Gauge with Two 18 Gauge Maximum Combination https://www.mcmaster.com/product/6878K95

They are nice in the limited case of needing to extend very short wires in a box where you can't replace the cable. Though the Wagos are probably better now a days.
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Thanks , they look identical to the ones that were in my garage for over 40 years. Amazed that the screw it accepts a broad range of wire sizes. Love McMaster Carr. I would order 40 boxes of 6/32,8/32 1/4" & 3/8" assorted hardware including fender washers etc and they usually had them all in stick. Stopped purchasing any hardware from Graingers due to cheating Chinese poor quality. Graingers flat washers were so thin even when you doubled them they would bend before finally torque pull.
 
Eddie702 said:
I usually put the red head on and use the flimsy bare strip to hold the RH in place. I was wondering what a Marrette was myself
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Some more Canadian info for you is our BX (AC90) does not come with a flimsy bare strip. It comes with a solid bare copper conductor typically one size smaller than the insulated conductors.
It also has paper between the conductors and the aluminum sheath.

IMG_8784.jpeg
 
Eddy_Current said:
Some more Canadian info for you is our BX (AC90) does not come with a flimsy bare strip. It comes with a solid bare copper conductor typically one size smaller than the insulated conductors.
It also has paper between the conductors and the aluminum sheath.

View attachment 2578423
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Think MC has largely replaced BX. Our BX still has paper AFASIK
 
Eddy_Current said:
Some more Canadian info for you is our BX (AC90) does not come with a flimsy bare strip. It comes with a solid bare copper conductor typically one size smaller than the insulated conductors.
It also has paper between the conductors and the aluminum sheath.

View attachment 2578423
Click to expand...
Sounds like what is called type MC cable in the states. In most commercial buildings in.my area you are not allowed to use inferior BX cable. Like the ideal of z full size copper ground wire on the #14, # 12 & # 10 gauge MC cable. Was told at continuing education classes that type AC ( BX ) cable has a heavier metal jacket then the type MC cable.
 
Eddy_Current said:
Some more Canadian info for you is our BX (AC90) does not come with a flimsy bare strip. It comes with a solid bare copper conductor typically one size smaller than the insulated conductors.
It also has paper between the conductors and the aluminum sheath.

View attachment 2578423
Click to expand...
So do you also have MC? Is the equipment ground always bare on your BX and Green on the MC?
 
garbo said:
Sounds like what is called type MC cable in the states. In most commercial buildings in.my area you are not allowed to use inferior BX cable. Like the ideal of z full size copper ground wire on the #14, # 12 & # 10 gauge MC cable. Was told at continuing education classes that type AC ( BX ) cable has a heavier metal jacket then the type MC cable.
Click to expand...
What about MC-ap without the green EGC is that acceptable? I don't know of any locale that has outright banned type AC but for the most part MC is always specified anyway except for type AC-HCFC.
 
If AC (BX) was banned it wouldn't be in the code book would it? The only problem wit AC is the connectors have to be tight to have a good EG. Some people are sloppy. Plus AC is heavy with the steel jacket.
 
Article 320.1 Enhanced Content
"Notwithstanding requirements that call for construction features available only in Type MC cable (such as an impervious nonmetallic outer covering), there are also requirements such as 516.7, 516.38, and 690.31(D)(1) that specifically call for the use of Type MC cable. Although many electricians generically refer to cables with an outer metal jacket as “BX,” it must be understood that the cable is either a Type AC or a Type MC cable and recognizing the difference between them is important to getting the installation correct. See 310.8(B) for information on how Types AC and MC cables are required to be marked."

Not sure if reuse or use of old stock BX is still legal to install, or if I would even attempt it if found But one on left is similar to some "newer" old BX. Picture from enhance content in 2023 NEC Article 320 Armored Cable Type AC. One on Left is similar to the first grounding conductor of the older BX then seen it with the same size but green insulation. Not there is no information beyond a mention in the enhanced content. Some commentary from the enhanced content of Article 320.1:

1751196441930.png
 
Fred B said:
Not sure if reuse or use of old stock BX is still legal to install, or if I would even attempt it if found But one on left is similar to some "newer" old BX. Picture from enhance content in 2023 NEC Article 320 Armored Cable Type AC. One on Left is similar to the first grounding conductor of the older BX then seen it with the same size but green insulation. Not there is no information beyond a mention in the enhanced content. Some commentary from the enhanced content of Article 320.1:
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Both of those cable are AC. The one on the left is standard AC. The one on the right is HCFC (health care facility cable) with the required redundant EGC.
 
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