new wire to an old fixture

I changing out an old junction box in the attic: one of the fixtures running off this box is a recessed can. (BTW the house is from '53 and this wiring looks original.) Probably 99% of the wiring in the house is NM - a cotton sort of braided wrap; the hot and neutral are rubber coated (insulation is in good shape, unlike the old crumbly stuff in the last house) and there is a bare copper ground wire.
Running from the junction box to the can is a piece of BX (armored) cable. The hot and neutral are stranded wire - most of my experience is with BX but I have never seen it with stranded wire. The insulation on the stuff is kind of crappy, too. At the can end, the installer put on crimp connectors. The screws where the wires connect do seem on the small side for 14 wire. So, my questions:
1. I'm planning to replace this 2' piece of cable with new BX. Can I use a crimp connector on the one end, or are those only for stranded wire?
2. Is there any reason to use stranded wire for this situation?
Thanks in advance. Bill
(Here's my guess for how this arose - the "junction box" I'm replacing is a ceiling box that is lay on top of the attic insulation (without a cover, no less), which leads me to believe the recessed can was a later addition. The previous (and only) owner of the house ran an air conditioning business. My guess is that he might have had BX around for that and used it for this installation. As far as the stranded wire - don't they use that with machinery when there is a lot of vibration? Like air conditioners?)
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It's not BX cable. It is flexible metallic conduit in which stranded fixture wires have been pulled into. Those wires have a higher temperature rating than BX or Romex cables from that time period. Check and see if there is a label on the fixture specifying the temperature rating for the feed conductors.
New BX and Romex are usually rated for 105 degrees celsius.
You can use crimp connectors if they have been approved for the purpose. There should be a UL symbol on the packaging and perhaps a specification sheet detailing their usage. Otherwise use wirenuts.
John Grabowski http://www.mrelectrician.tv

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I kind of wondered if he had just pulled some wires through an empty piece of BX: didn't know they sold it as conduit, but it makes sense as a flexible version.
Maybe I'll just pull some new wires through the same piece.
There's no temp rating on the can fixture - only part of the label is still legible. Is the wire in BX generally adequate for a can fixture, or do I need a higher temperature rating? (In this can, the wires are connected to a porcelin lampholder that sits inside the can.
Thanks Bill

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You may need a higher temperature rated wire if you are using bulbs greater than 60 watts. If you were to look at new recessed fixtures, they have a separate junction box where the feed conductors get spliced to the lamp conductors thereby separating the feed conductors from extreme heat. See what the temperature rating is on those lamp conductors. I don't know why you want to replace the flexible conduit and fixture wires to begin with?
If you are going through the trouble of replacing the feed wires I suggest that you replace the old recessed can with a new one. You will have an assortment of trims to choose from, it will be up to modern standards, and you won't have to worry about heat damage to your BX.

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The fixture wires don't look (to my eye, anyway) in great shape, so I figured I would replace them.
I'm going to look at new fixtures this weekend, then either go that way or get new stranded wire with the necessary temp rating.
Thanks very much. Bill
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If they are the type I am thinking of (Type AF), they have a sort of waxy finish to the outer sheath. They usually look as though they are bad, but unless they are dry and the insulation is crumbling off, the wires may still be in usable condition.
John G.

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bill wrote:
...

...
A crimp connector won't work well on solid wire if it's crimped with an inexpensive general-purpose crimp tool. If you have something like an Amp type W crimper you can make a good connection to solid wire. Amp tools are _very_ expensive, however.
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--
--
Steve

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