wires-BX,armour,and trivia

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Old 03-21-11, 01:23 PM
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wires-BX,armour,and trivia

Albany,Ny-BX cable,amoured cable,etc I get confused as to what it is called. I usually call it bx.Wire loom inside that bx cable( i just found out from these forums that that old wiring inside is called loom-which is rubber with cloth wrapping).The actual wire inside this insulation is copper but what is the coating on it? is it oxidation or is it zinc or something else? I did alot of rewiring,new receptacles,moving wires around,etc for my customer in her old house.Establishing ground continuity at recepts. and light fixtures and between boxes,reversing polarity(center screw for center bulb contact[whoever did this wiring years ago didn't know what they were doing] in incandesant bulbs the current can flow either direction but for these new CFL's, I think it matters,but either type bulb i still think it matters that the flow should go the same way,right?) on old light fixtures,fixing switched hot instead of common to light fixtures.At each end of the wiring at these locations I used my linesmans to scrape this coating off to either attach them directly to terminals or if they were to short,I pigtailed ,wire nutted and attached to terminal screws. In extreme cases were the broken wire insulation was too deep in the box to wrap with elect. tape I used liquid elect. tape.Are these safe practices?Wire loom,when did it go out of usage?I believe I heard of "as long as it's not disturbed it's ok".Upon opening boxes to replace old recepts. and fix grounds ,polarity and/or hot switching on light fixtures,most of of these wires had their insulation breaking off or already had the insulation come off with time,especially the hot which I insulated them with great care.How can I tell what the gauge size was at these locations or did they use the same for all?lights 15 amps 14 gauge, and receptacles 15 or 20 amp always 12 gauge wire?20 amp rated recepts.goes with 12 gauge and 20 amp breaker.What about a 15 amp rated recept.with 14 gauge wire and 15 amp breaker? I sometimes get confused as to what should be done here. Then there is also with residential wiriing(I know commercial gets armoured cable and metal boxes),but what about when or when not to use plastic boxes or metal. My usual is always using metal boxes with separate screw type clamps for either bx or NM surface mount or in the wall. I always thought that metal boxes were for keeping a fire inside of it to control it from spreading if it were to over heat and catch fire,am I right?I know that I can't use bx cable in a plastic box.I twist wires a little then twist with a nut tightly and give a wrap to the wire and nut at juctions,this is good, right? or is this a waste of time and tape?,I've shortened it to only the hot wire.I wrap the switch or recept. terminal screws in metal boxes. I used to pigtail the ground wire for NM to the metal box and to the ground screw of that switch or recept.That's Canadian code according to the home depot book.When some licensed electrician or handyman in the near or distant future see's my wiring they are going to say"Why did this guy do this this way?",lol!.I also found out on the job by myself to test a bulb without screwing it into a live fixture- doing a continuity test-cfl's nor (of course) tube type flouresants can't be tested,good incandesants will beep(i knew that).How about a live light fixture socket with a none contact voltage tester-did you know that if the center contact terminal is made of aluminum instead of brass you can't ....I'll get back to you on that one..I forgot. How bout this one I found out on the job by myself-no one there to tell me this-this is not made up people.While I was fixing those live wires..I was holding that hot wire with a pair of good linesman pliers on the insulated handles of course scraping that whatever it is coating off and held for whatever reason my non-contact voltage tester in my other hand(the tester was set to 'on') and it was beeping with my arm fully stretched out away from the hot wire level with my shoulder,when I moved it up over my head the beeping stopped,when I brought it back down and below shoulder height it was beeping,mind you I was holding the tester at it's handle the whole time...why this happened I don't know..I can't figure EVERYTHING out myself....lol!
 
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Old 03-21-11, 01:48 PM
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Questions

Can you state the question one simple sentence?
 
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Old 03-21-11, 01:57 PM
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Wall of text! Try to be more brief or at least use paragraphs and formatting, as I'm not sure what all of your questions are.

BX cable,amoured cable,etc I get confused as to what it is called. I usually call it bx.
The generic name is "armored cable"; Bx was a brand name (sort of like Xerox vs. copy machine).

copper but what is the coating on it?
Many older copper wires are "tinned" with a thin coat of tin-based solder to prevent corrosion. This coating may be left in place.

In extreme cases were the broken wire insulation was too deep in the box to wrap with elect. tape
Wires with insulation that is completely damaged should be replaced. There is no approved repair method.
 
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Old 03-21-11, 02:50 PM
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The wires inside of armored cable are not called loom. Neither is non-metallic cable (often called Romex although that is a brand name) loom as at least one book I read called it.

Loom is the flexible non-metallic tubing used over individual conductors in the knob and tube wiring when the wires enter a junction or fixture box.

As Ibpooks stated, the silvery coating on the copper wires is tin/lead solder. It was used because the rubber insulation used on these wires had a tendency to corrode the copper. It is no longer necessary with the plastic insulations now in use.

Plastic boxes may only be used with non-metallic wiring methods, most plastic boxes are only for use with non-metallic cable although there are some plastic boxes that have round holes that will accept non-metallic conduit.

There are two things that cause rubber-based wire insulation to deteriorate, heat and oxygen. The heat issue comes from over-fusing of circuits and/or from over-lamping of (mostly) ceiling fixtures. Not that it generally is any help but quite often the rubber a few inches back from the open end of conduit (including flexible) is still viable while the insulation at the boxes and devices is dried out and crumbling off the wire.

The "polarity" of screw-in light fixtures is important not for current flow direction (it changes 60 times a second as you know) but for personnel safety. Having the "grounded conductor" (neutral) connected to the lampholder shell makes it safer for the person that removes and installs bulbs with the power on if they accidentally come into contact with the screw shell while also having some other part of their body grounded in some manner.

Back in the "olden days" most residential general purpose circuits were wired with #14 conductors. Only very specific circuits such as electric kitchen ranges, electric water heaters, electric "in-wall" space heaters and occasionally a special receptacle for a portable electric heater were wired with larger wire. Unfortunately, back in those days they also used fuse boxes that had screw-based fuses that allowed the use of several different fuse ratings with the same screw base and also some with cartridge fuses could also use varying ratings of fuses. With more and more electric appliances, especially in the kitchen, it was common to overload the circuits and the cure by the homeowner/tenant was often to use the next larger fuse rather than have the wiring upgraded. I have actually seen 30 ampere fuses used in circuits wired with #14 (15 ampere) wire.

Also unfortunate was a common practice when amateurs replaced fuse boxes with circuit breaker panels was they would use a circuit breaker of the same rating as the fuse it replaced rather than rating the circuit breaker according to the wire size. One of the complaints against circuit breakers was that it "didn't allow any flexibility in the management of various circuits in a home. This was (and is), of course, one of the greatest assets of circuit breakers. To combat the bigger fuse issue, at least with the screw-in fuses, the "type S" fuse was developed that used an adapter that was screwed into the fuseholder (and was then not removable) that would only allow special fuses of the correct rating to be used. It was a good idea and type S fuses and their adapters are still available but the circuit breaker revolution happened at about the same time as the development of the type S and since circuit breakers are resettable they won the day.
 
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Old 03-21-11, 05:46 PM
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Back in the "olden days" most residential general purpose circuits were wired with #14 conductors. Only very specific circuits such as electric kitchen ranges, electric water heaters, electric "in-wall" space heaters and occasionally a special receptacle for a portable electric heater were wired with larger wire
I have seen 10 and 12 knob and tube, although most of it is 14. I have also heard of the practice of pennies in the fusehoulder which is worse than a 30 because at least a 30 can clear a fault.
Not that any method is in the least safe, and both will start a fire.
 
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Old 03-22-11, 10:49 AM
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Ok,now I get it.BX is a name brand and what it really is called is armoured cable."Plastic boxes may only be used with non-metallic wiring methods, most plastic boxes are only for use with non-metallic cable although there are some plastic boxes that have round holes that will accept non-metallic conduit."(as stated by Furd).Do you mean that I can attach plastic conduit tubing into a plastic box and then run those wires through that conduit? "There are two things that cause rubber-based wire insulation to deteriorate, heat and oxygen. The heat issue comes from over-fusing of circuits and/or from over-lamping of (mostly) ceiling fixtures. Not that it generally is any help but quite often the rubber a few inches back from the open end of conduit (including flexible) is still viable while the insulation at the boxes and devices is dried out and crumbling off the wire" This sounds correct but there is also another factor I believe to be correct in kitchen light fixtures is that of course heat rises and this heat comes from the gas stove/electric range and in older homes such as mine with a gas space heater and stove combo, I get twice the heat rising,I wonder if the cooking oils that rise have an effect on that insulation as well.When I remodeled my mother's basement apartment and opened up that ceiling light box and saw how bad those wires were I almost fainted-they were all replaced. Thanks guys for the info.
 
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Old 03-22-11, 11:08 AM
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Originally Posted by MeticulousMike View Post
Do you mean that I can attach plastic conduit tubing into a plastic box and then run those wires through that conduit?
Yes. Plastic conduit can be used with plastic boxes.

Metal boxes can be used with any type of cable or conduit. Plastic boxes can only be used with plastic cables or plastic conduits.

I wonder if the cooking oils that rise have an effect on that insulation as well.
Food-safe oils (lard, canola, veggie, etc) should be non-harmful to wiring insulation, although could probably become a fire hazard if they build up in excess. Petroleum oils and solvents (gasoline, kerosene, motor oil, thinners) will cause damage to rubber insulation.
 
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Old 03-22-11, 12:10 PM
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according to Wikipedia- loom is the cloth that surrounds the outside of the rubber insulation for added protection.So this type of wire inside old armoured cable IS called loom wire,right?
 
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Old 03-22-11, 12:16 PM
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It's called scrap as far as I'm concerned.
 
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Old 03-22-11, 12:22 PM
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yes common sense shows that petroleum oils and solvents will destroy rubber insulation and asphalt soaked jute insulation-silicone based oils(ie,wd-40) will destroy the latter as well.
 
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Old 03-22-11, 03:26 PM
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Originally Posted by MeticulousMike View Post
according to Wikipedia- loom is the cloth that surrounds the outside of the rubber insulation for added protection.So this type of wire inside old armoured cable IS called loom wire,right?
NO! Loom is an additional tubing used with the knob and tube wiring system when the individual conductors enter a junction, switch or receptacle box. It is loose and slid over the wires insulation to further protect that insulation from the pressure of the clamps in the box.
 
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Old 03-22-11, 03:31 PM
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Knob and tube wiring - Wikipedia, the free encyclopedia:
Where conductors entered a wiring device such as a lamp or switch, or were pulled into a wall, they were protected by flexible cloth insulating sleeving called loom.
 
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Old 03-22-11, 05:07 PM
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Loom is the fat stuff around the wires. I hope to replace it this summer. It is feeding my garage.

Also, fryer oil ate through my bubble cover on my extension cord. The wire and compression clamp was unharmed.
 
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