What type of wire is this?

[xbanone]

So I am changing out some switches and outlets in my 1930's home and came across a few things that I am curious about.

First, what type of wire is this and is it safe? Is there any special attention that I need to give this type of wire?

Second, there is no ground wire in this part of the house. One of the outlets had a jumper wire from the unused common connection on the outlet to the ground screw. Is this an acceptable method or recommended?

 

[nehog]

Personally I'd not use/re-use that wire. The no ground is a major issue, and the insulation (cloth) will be fragile at best... If you an pull new wire into the boxes I think you should.

 

[gluckmysock]

I agree. I see its a switch, but never ever wire a 3 prong outlet onto this wire. Its not grounded (3rd wire) and you can easily become french fried chicken.

You are better off to pull new wiring from the breaker box. when houses were first wired the used a technology called; Knob and Tube.

http://www.ehow.com/how_2097628_remove-knob-tube-electrical-wiring.html

This kept the 2 conductors seperated via porcelain tubes and mounted on porcelain knobs.

very old technology.

 

[Norcal]

It is NEVER acceptable to jumper from the neutral to the grounding termina.l (Called a "bootleg ground"). if one wishs to replace the non-grounded receptacles w/ grounding type , a GFCI may be used, if on the 2008 or later NEC the replacement receptacle must also be of the tamper resistant type.

 

[Charles (in GA)]

It is NEVER acceptable to jumper from the neutral to the grounding termina.l (Called a "bootleg ground"). if one wishs to replace the non-grounded receptacles w/ grounding type , a GFCI may be used, if on the 2008 or later NEC the replacement receptacle must also be of the tamper resistant type.

And the outlet must be placarded "GFCI Protected" and "No Equipment Ground".

Charles

 

[Bigpigdave]

I agree. I see its a switch, but never ever wire a 3 prong outlet onto this wire. Its not grounded (3rd wire) and you can easily become french fried chicken.

You are better off to pull new wiring from the breaker box. when houses were first wired the used a technology called; Knob and Tube.

http://www.ehow.com/how_2097628_remove-knob-tube-electrical-wiring.html

This kept the 2 conductors seperated via porcelain tubes and mounted on porcelain knobs.

very old technology.

The wire the OP has is not "knob and tube". It is early NM cable. The other posters are correct that the cloth insulation becomes very brittle over time. I would be very careful reusing this wire.
JMHO, Dave

 

[BJ42LX]

What type of wire is that?

Scrap.

 

[Teken]

It is NEVER acceptable to jumper from the neutral to the grounding termina.l (Called a "bootleg ground"). if one wishs to replace the non-grounded receptacles w/ grounding type , a GFCI may be used, if on the 2008 or later NEC the replacement receptacle must also be of the tamper resistant type.

Norcal,

Can you clarify how the use of a GFCI can enable a grounding path if none is present?

 

[rockwithjason]

Norcal,

Can you clarify how the use of a GFCI can enable a grounding path if none is present?

It doesn't. a gfci compares the current in the hot and the neutral wires. if the difference is more than 5mA or so the gfci breaks the circuit. in effect if the current goes outside of it's correct path (a ground fault) the gfci breaks the circuit. this is an acceptable safety measure in the absence of an equipment ground.

 

[Thruxton]

That is old "armored" or BX, and the big insulation problem is not the ratty looking fabric sheath, it is the rubberlike insulation on the conductors, which breaks and falls off when you look at it, and which you will see as soon as you examine what you have disturbed. It is scary stuff. I rewired my attic and upper floor last year to get it out of my house. A fire hazard AND an electrical hazard both were just too much for me to live with.

 

[ishiboo]

Since it's just a switch, a ground isn't "that" important.. though the rest of the house will likely be wired similarly.

It's either copper (which it appears to be) or steel, not aluminum, should be fine to re-use. If I have to make a repair to this wire, I use a piece of heat shrink over the cloth to keep things together and safer.

 

[VHF]

If I had wire like that in my house I would install arc-fault (AFCI) breakers!

 

[Norcal]

If I had wire like that in my house I would install arc-fault (AFCI) breakers!

Why? They are just snake oil.

 

[May Pop]

X2 on the heatshrink over any damaged insulation.

 

[gluckmysock]

The wire the OP has is not "knob and tube". It is early NM cable. The other posters are correct that the cloth insulation becomes very brittle over time. I would be very careful reusing this wire.
JMHO, Dave

I stand corrected.

GMS

 

[GTVi]

I never play with electricity...if the wire is THAT old, better to err on the side of caution and replace it. It helps if you know a sparky.

 

[metal1313]

my house has this stuff. it might take a little more caution but re-using it isnt anything that hasnt been done. for everyone saying pull new wires..i gotta ask you ever tried to pull a decent amount of wire through an old house, with plaster and lathe walls?

i will be re-wiring my house soon, since i do have a mix of romex, k and t, and bx cable. got some quotes last year, 8k to 22k plus 3-5 k in plaster repairs, along with repairs to plaster mouldings that could total another 5k. i will end up wiring the upstairs from above, and the first floor from below. just have to figure out the best method to wire all the ceiling lights w/o damaging the moulding

 

[dangle]

Looks like aluminum wire to me, no?

aluminum wire = 65% conductivity compared to copper of the same size
aluminum wire + copper screw = galvanic corrosion = increased electrical resistance
aluminum wire + copper screw = different coefficient of thermal expansion = loosening of connections

All of these things lead to overheated and loose connections which present a major fire hazard.

If that is in fact aluminum wire, I'd start replacing it immediately.

 

[rabidsquirrel]

Looks like aluminum wire to me, no?

Looks like tinned copper to me.

 

[boozer]

I have that exact stuff in my house. I have heard it called BX as well. It's super tough stuff, but has many strikes against it.

un-grounded
mine is 14 Ga (20 amp breakers installed when I bought the house yikes!)
Cloth-covered insulation (flammable!!! ask me how I know)
possibly aluminum conductors (although maybe tinned copper)

 

[rabidsquirrel]

Aluminum wire wasn't used for branch circuits until the '60s. That stuff is tinned copper, and it's not BX, from approximately the '30s.

 

[VHF]

Why? They are just snake oil.

I think requiring AFCI for new construction is ridiculous, but don’t you think they would provide some additional protection when dealing with old wiring with marginal insulation? Or are you saying they don’t really work at detecting arcs?

 

[pprince]

I have that exact stuff in my house. I have heard it called BX as well. It's super tough stuff, but has many strikes against it.

un-grounded
mine is 14 Ga (20 amp breakers installed when I bought the house yikes!)
Cloth-covered insulation (flammable!!! ask me how I know)
possibly aluminum conductors (although maybe tinned copper)

It's not bx. Bx is metal sheathed.

I agree its tinned copper

 

[jdaallen]

So I am changing out some switches and outlets in my 1930's home and came across a few things that I am curious about.

First, what type of wire is this and is it safe? Is there any special attention that I need to give this type of wire?

Second, there is no ground wire in this part of the house. One of the outlets had a jumper wire from the unused common connection on the outlet to the ground screw. Is this an acceptable method or recommended?

Just to add to the problem here -- That cloth insulation more than likely contains asbestos. When you are working with it, do not generate any dust from the wire and wear a good quality dust mask. If you have your entire house wiring changed out, it becomes an asbestos abatement project by most states and EPA/OSHA rules.

 

[rabidsquirrel]

I doubt that that cloth covering contains asbestos. It was only used where it would come into contact with high heat, which wouldn't be a switch in the wall. That looks like ordinary cloth wire.

Asbestos has a unique look to it.

http://www.flickr.com/photos/asbestos_pix/4032452759/

-edit-

Now if this were an old cloth covered feeder, I've heard of the old timers spraying them down with a mix of water/arsenic to stop the rats from chewing on them.

 

[jdaallen]

I doubt that that cloth covering contains asbestos. It was only used where it would come into contact with high heat, which wouldn't be a switch in the wall. That looks like ordinary cloth wire.

Asbestos has a unique look to it.

http://www.flickr.com/photos/asbestos_pix/4032452759/

-edit-

Now if this were an old cloth covered feeder, I've heard of the old timers spraying them down with a mix of water/arsenic to stop the rats from chewing on them.

Your correct with the photo of that particular application and anaylsis of the wire would show around 40 to 60% asbestos content. However there were many house hold wirring products similar in look as the original picture that contained asbestos at a much lesser amount around 3 to 15%. This wirring didnot have the "fuzzy look" Anything greater than 1% is regulated by EPA and any content is regulated by OSHA.

 

[nehog]

Some house wiring did contain asbestos... Often can be spotted by seeing small white fibers in a darker insulation. The photo from the OP doesn't seem to have wire with asbestos.

I'm not aware of using arsenic on wires to stop rodents (problem is that arsenic is a slow acting poison, so the wires would be destroyed before the rodent died!) But that's not to say it was not done!

I could be wrong, but it is possible the 'cloth like' insulation in the OPs wiring is linen.