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Posted By: SvenNYC What connector do you prefer for BX cable? - 02/15/04 01:56 AM
I've always been leery of the type that uses a set screw to bite down on the armor. I saw three different types today at Lowes.

One was a type that uses metal straps held in place with two screws at opposite ends. Another type is a sort of compression fitting. A third has a saddle (a piece of metal inside the connector body) that clamps down on the armor.

Each of these seem like they avoid damaging the armor. I've always been leery of having the set screw pierce or crush the armor, yet I want to have a good reliable ground connection. [Linked Image]
Posted By: hbiss Re: What connector do you prefer for BX cable? - 02/15/04 06:43 AM
Those old set screw connectors are only good for steel type AC. Nowadays you are likely to run into type MC as well as aluminum armored type AC. To save alot of confusion I only buy connectors listed for all three types, check the box. I'm not familiar with the compression type you saw but the other two sound good.
HBISS,

The compression connector is a sort of sleeve with a screw on the side. When you tighten the screw the sleeve tightens around the armor.

I liked the design of that one the best because it seems to apply even pressure around the armor, not at one or two points (so it probably won't crush or flatten the armor as easily).

You're right about checking the master-boxes they are shipped in. The individual baggies used to wrap the connectors don't offer much of an explanation.
We use the Arlington Snap2it line heavily at work when installation speed is a factor. Otherwise we use the T&B CI70 (single) and CI2175 (duplex).
http://www.aifittings.com/arliprod3.htm
http://www.tnb-canada.com/catalogues/pdf/en/iberville_roughing_in/roughing_01b_eng.pdf
I always used speed locks unless I was doing a cut-in box, in which case I used the one that looks like a romex connector.
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yet I want to have a good reliable ground connection.

Most modern BX has a bare wire runner just inside the armor and outside the paper wrapping covering the white and black wires. As I understand it [Linked Image] you're supposed to take this bare wire and bend it over the antishort you just stuck in so it doesn't fall out, and then wrap the bare wire back around the outside of the armor so it lays in the groove between adjacent wraps of the armor. Then fit the connector over that and clamp it so the litle indents in the clamp clamp that bare wire. That you're not supposed to have any of this bare BX wire inside junction boxes, unlike romex. The metal box is then your ground connection.

Some BX has aluminium armor sheathing, and it says not to use set screw connectors with it.

Why is it that there is no problem with this aluminium armor BX cable with copper wire inside, but aluminium romex wiring caused lots of trouble? The ground has to be able to take a fault current.
Combined with the armor, yes, it makes a good ground.
heres my theory regarding the aluminum. The main problem with the aluminum is that a very small amount of corrosion increases the resistence slightly. the actually corrosion doesn't cause that much of a problem. However, the heat causes expansion and contraction of the joint. after a while this loosens the connection. thats when the real problems start. In the case of aluminum BX, since there is not normally current flowing in it, the juntions don't experience the heating and cooling that loosens the connections in the current carrying conductors. therefore, even if there is some corrosion, there is still a sufficient ground to trip a breaker in the even of a ground fault.

It's just like steel conduit. it's used for a ground, but when was the last time you saw a steel conductor? (yes, i know some people on here actually have seen them) [Linked Image]

[This message has been edited by cpalm1 (edited 02-16-2004).]
Posted By: hbiss Re: What connector do you prefer for BX cable? - 02/17/04 12:31 AM
The compression connector is a sort of sleeve with a screw on the side. When you tighten the screw the sleeve tightens around the armor.

Yup, I think I know what you are talking about. It's not really a compression connector but just another type of clamp. They have actually been around probably longer than the set screw connector. I kind of like them myself when I can find them. They grab the armor real well.
Posted By: iwire Re: What connector do you prefer for BX cable? - 02/17/04 12:46 AM
1 [Linked Image from bptfittings.com]

2 [Linked Image from bptfittings.com]

3 [Linked Image from bptfittings.com]
I prefer the #2 type, shown in Bob's picture (iwire's picture).
It looks like the ones with the "forked bracket" that sets on the MC Cable's sheathing, and is adjusted / set via the 8/32 screw.

Scott35
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I always used speed locks unless I was doing a cut-in box, in which case I used the one that looks like a romex connector.

Ryan_J, Why don't you use speed locks or snap in connectors when doing a cut-in box?
Personally, I use the Arlington "Speedlocks" & have never had a problem with them.... I've used the Arlington version of the #2 connector with the set screw & never had a problem with those either... The speedlocks are awesome when you need to fish MC down a wall to an existing J-box.. No locknut to fuss with.. [Linked Image]

-Randy

PS... I get a good reliable ground connection by bonding the ground wire where appropriate, this typically bonds the outer sheath at both ends via the connector & box. [Linked Image]
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The speedlocks are awesome when you need to fish MC down a wall to an existing J-box.. No locknut to fuss with..

Yea but how do you snap in the connector without getting a hold of the MC cable?
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Ryan_J, Why don't you use speed locks or snap in connectors when doing a cut-in box?

I always attached the clamp on the cable, then put it down the wall, then threaded the locknut on after the the cable was in the box and the box was in the wall. Speed locks just seemed like a PITA for this application. Do you use them for cut-in boxes?
Straightedge...
A quick, little tug on the wires entering the KO once its down into the box secures the snap in connector [Linked Image] Otherwise, trying to get a locknut tight on a connector, when you can't grab the other end of it is kind of a pain in the #$$..

-Randy
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I always attached the clamp on the cable, then put it down the wall, then threaded the locknut on after the the cable was in the box and the box was in the wall. Speed locks just seemed like a PITA for this application. Do you use them for cut-in boxes?

I'm with you on that one Ryan_J. I specifically carry both types of MC Connectors on my van. I am loyal to the Snap-In Connector except for cut-in-boxes. I have to go with the thread and lock ring for my cut in boxes.

I don't know how Lostazhell can snap in the Connector without pulling the conductors out of the cable.

Maybe he can expand a little more?
Posted By: BigB Re: What connector do you prefer for BX cable? - 05/14/04 03:29 AM
I use the snap ins all the time on cutins. Just grap ahold of the wires and pull with a slight rocking motion and click click its in.
Straightedge,
Big B explained it perfectly [Linked Image] I'll fish the MC down the wall with either my fiberglass "pullstick" or something else... I pull the wires through the KO opening, A little tug on the wires back & forth & everythings in place.. Unless youre pulling a piece of MC less than a foot long, good chance the wires are not going to pull out of the MC sheathing. (At least it's never happened in the 100 or so times I've done this)

-Randy

[This message has been edited by Lostazhell (edited 05-14-2004).]
Well, when I do a cut-in-box the walls are usually only 10' high. Only a 15' peice of mc cable is necessary. I can never get the snap-tite connector to fully engage into the knock out without pulling a significant length of conductors out of the matal sheathing.

I use lock ring type of mc connectors for this application.

Tev
Posted By: e57 Re: What connector do you prefer for BX cable? - 03/10/05 02:36 AM
Those Snap2it things are great for fishing....

If a tug doesn't seat it, grab it at the KO and pop it in with a pair of needlenose or Knipex channel locks.

I too have come across different brands of MC that the conductors will pull out of. And occasionaly some that is still soaked in degreaser from the factory, so the whole inside of the cable is 'lubed', you could easily pull out 20'. One place I go to has the "cleanest" MC around (when I stock the truck I go there), no blackened hands....
We used to use the speedlocks but switched over to the snap in due to cost mostly (was about 40% the price) and speed of install. Only thing I dont like is trying to remove them from a 4^2 with a single gang P-Ring.

I use the two screw connectors for cut-in boxes mostly, but I have used all 3 types of connectors with success.
I have also taken a small screwdriver and slipped in between drywall and box(covered by plate_ to help snap in those difficult connectors or to remove any debris ie insulation etc that is blocking a piece of bx the snap in rings work like a champ but then again so do the romex type just a little tougher...I have also used the screwdriver trick to hold the connector in while starting a lock nut.....
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