Old BX or new Romex? What would you do?

[Nate Nagel]

Which would you rather see in a basement for wiring? Old BX or new Romex? I'm really not sure which should be preferable. BX has cloth covered insulators and just the little strip for ground, but it is working well (was working on a switch hot and accidentally touched the box, the lights were off almost simultaneously with the spark - woops. Just for the record I was wearing my work boots and was careful not to let my hands touch anything metal; I just didn't realize that the switch I was using was almost as wide as a single gang box...) cloth covered insulation appears to be in good shape. I like the damage resistance of the BX, but I also like the higher temperature rating of the new NM-B.

I'm certain that the old cloth had a 60C temperature rating if any; new NM-B has 90C. Does it really make a big difference? I know the right answer to the question is "use new BX with 90C insulation and a separate ground wire" but... um... you priced BX lately? I am definitely replacing a few runs with romex to allow for a 3-way switch on the stairwell light and will be replacing a couple lampholders with shop lights (cheap 'n' sleazy, just using short fixture whips out of the blank plate of the octagon box, there's no ceiling in the laundry room and won't be until *ALL* the wiring is done)

Also, in situations where someone's already been there and pulled somewhat-newer Romex, do you generally consider it acceptable to "repurpose" it if it runs where I need it? This is all the old NM not NM-B, and for extra goodness some of it has a 16AWG ground. Is this a big deal? Repulling it is not the end of the world, just a minor PITA. I know it's not the best it could be, but ISTM that it should be acceptable...

Oddly enough, this whole line of thought was prompted by the light at the bottom of the stairs going out as I was pulling a piece of Romex through the same space. Whenever I knocked against one of the pieces of BX going into the ceiling box (I was reaching above the ceiling space between the studs) the light would go out, and then when I touched it again it would come back on. I figured this needed immediate attention, and I just imagined that I'd find that I'd have to repull all of the runs that entered the box due to it being fried. Imagine my surprise when I pulled it down and everything looked fine inside, but when I removed the lampholder itself the neutral screw was loose. OK, reinstall, works. Left it dangling from the wires and carefully wiggled the two wire nuts inside the box. When I wiggled the neutral, the light would flicker. Not good! removed wire nut, here it didn't have any spiral steel insert and was very loose on the wires. Some electrician - presumably back in 1948! - didn't notice it, and here it was to freak me out 60 years later... A new wire nut out of the electrical drawer and all is working fine now :)

nate

(getting in practice for all the hidden work...)

["Blattus Slaf]

Well the old BX in my previous house had for a 15 amp circuit a wire feeding the dining room and living room, all the outlets and overhead lights, then it went up to the second floor and ran 3 bedrooms outlets and lights and the bathroom and a hall closet light. That I would replace with Romex with additional circuits.

[Nate Nagel]

That's not an issue... at least not one pertinent to my question. This circuit serves only the basement lights, period - so when all is said and done there'll be two troffers, two shop lights, and one fixture on the circuit. Now the second floor, that's a different story - I do have one 15A circuit serving three bedrooms, the bath, and a hallway. That'll all get replaced with at least three circuits pulled in new Romex (one 20A for the bath and the rest split into two circuits)

nate

[Big_Jake]

Leave it. Better to have the metal jacket to shield it from damage. If it ain't broke...

JK

[RBM]

Old cloth covered AC cable was in my opinion, the worst of all building cables. Anything would be better

[John Grabowski]

I vote for new. When you go to sell the house it will look better to have new wiring. I don't like working with the cloth covered conductors.

[hallerb]

s.- Hide quoted text -

We agree on this........

[dicko]

This, if anything is an understatement. My house has this crap and I am slowly replacing it as I get a chance.

The problem is that its rubber insulation with a cloth covering. As it gets old, the rubber becomes brittle. Any time you move a wire, the rubber cracks and falls off and creates a shorting/fire hazard.

At the very least, If you ever open an electrical box for whatever reason, you should put some heatshrink tubing over the pigtails sticking out of the BX to hold the cracked insulation in place.

-dickm

[N8N]

That's what I *expected* to see, but the rubber is actually quite pliable and appears to be in good shape, hence my question.

I'm kinda leaning towards leaving the BX in place because a) the armor is nice, and some of the holes through the joists might be a little close to the underside of the joist and b) I'm not a big fan of replacing stuff that doesn't need to be replaced. Maybe it's in better shape here because there are only porcelain lampholders and not actual fixtures, and all boxes are in an open area except for one, which is above the ceiling but also somewhat open, so heat doesn't build up so much?

nate

[Pete C.]

Ignoring the wire issues, if the above is the case, I'd consider finding and installing some reinforcing straps (Simpson stuff probably), or sistering / sandwiching some reinforcing on the joists with holes near the bottom. Might be overkill, but I don't like to see compromised structures like that.

[HerHusband]

My personal preference would be new Romex installed through holes drilled in the joists (NOT stapled to a beam or the underside of the joists). If the BX is not stapled in place, you can use the old cable to pull the new Romex through.

If drilling the joists is not an option, I would use surface mounted PVC conduit and individual wires.

On the other hand, if the original BX cable is still in good shape, there's no immediate need to replace it. Just replace it where needed and update the rest to Romex as time and money allows.

That said, I've heard local codes in some areas require conduit or metallic shielding for ALL wiring. I think the Chicago area was one of them, but I don't remember for sure. You might want to check with your local permit office (and probably get an electrical permit).

Lower temperature wiring can be a big problem around light fixtures. The heat from the light makes the insulation brittle, which flakes off and leaves exposed conductors. I've worked on lots of lights in old houses that have completely bare wires, just waiting to start a fire. Kind of scary when you open it up and see that.

Still, you don't necessarily need to replace the entire run. Just mount a junction box nearby and run the higher temp Romex from the light to the junction box. Then tie the old cable into that and join the two cables in the box. Replace the circuit later when you have the time.

Anthony

[Nate Nagel]

The way this house was wired, it appears to be one of those areas where BX was only required in "exposed" areas, that is, the basement. The rest of the house is non-metallic. I'd actually be happier if the whole house were BX as at least then it would be grounded, if not well. So I can replace the BX easily as it only exists in exposed areas.

I have not asked the question yet, but judging by the presence of Romex all over the place where things have been messed with (some not so well, and already removed) the requirement for BX in the basement was apparently lifted long ago. There apparently was a permit pulled for some renovation about 20 years ago, either kitchen or basement I assume, so it must have been inspected and passed.

nate

[RBM]

If there is or was any requirement for steel cable in the basement, it was a local requirement

[Big_Jake]

So, you would rather have knob & tube or 2-wire ungrounded NM?

JK

[Nate Nagel]

you mean the stuff the REST of the house is wired with? :(

At least the (ungrounded) NM does not use cloth covering on the individual wires; I'll give it that. But the lack of a ground kinda sucks, because it severely limits my choices of fixtures (at least ones that can be installed and be code compliant) until I can rectify the ground issue.

nate

[HerHusband]

Nate,

If the cable is "exposed", such as running down a wall to an outlet you would still need some kind of protection. BX cable would comply, as would conduit.

Normally, you wouldn't want to run Romex in conduit, as it can build up heat. But it's allowed by code for short runs for "protection" purposes. I installed a circuit in my in-laws basement. The main runs are 12/2 romex running through holes in the joists. Anywhere I had to drop down to an outlet, I installed a short drop of 3/4" PVC conduit and a surface mount PVC electrical box. At the top of the conduit I installed a male adapter and a screw on bushing to protect against chafing.

Anthony

[HerHusband]

Assuming the insulation is in good condition, either is actually quite usable electrically (though the lack of ground is a problem).

However, you can insulate around NM wire, whereas you're not supposed to insulate around knob and tube wiring. I think it's because the insulation doesn't hold up to the increased heat build-up.

Anthony

[autobus_prime]

L: Maybe there never was a spring. It could be an old porcelain wirenut. Of course, in that case, the wires should have been twisted tightly enough beforehand to make good contact.

I wonder about this, too. I have one circuit with some plastic Romex that is old enough to have a 16 gauge grounding conductor. It's gotten pretty hard over the years - not enough to be brittle...not yet. Of course, THHN's nylon jacket should last a very long time, even if the thermoplastic layer is compromised.

A P

[bud--]

The current Romex (NM-B) has 90 degree C insulation. One reason is because Romex was being put in insulation.

Old K&T has 60 degree insulation. But so did Romex until relatively recently. And with the old Romex 2 conductors, and their generated heat, are run immediately adjacent.