Replacing asbestos wire

[Jesse Crooks]

I'm looking into replacing the asbestos wiring in some antique projectors and was hoping someone might be able to point me to the appropriate heat/UV resistant wire to replace it with. Combing through the old posts I found recommendations for fiberglass or teflon coated wire, but was wondering if there is a specific rating to look for, etc. This is for low intensity carbon arc (drawing 18A) and 1000W Mazda incandescent, so it only needs to be 14AWG.

I'll note that this is for projectors that I tend to build up and break down a fair amount for demonstrations / rotating lobby displays, so I have to handle it a fair amount. That's why I'm looking to replace it rather than just let it be.

[Steve Guttag]

Look into welding cable. It is highly flexible and deals with the higher current DC well. It is available in Black and Red too so keeping polarity straight is easy enough. That said, it will probably tough to find it smaller than 8awg. 18A should be on 12awg minimum. I tend to go a bit higher to avoid it heating up so 10 or 8.

[Thomas Piccione]

Second on the welding cable. The stuff I've used is very finely stranded so even a very thick cable is nice and flexible, especially compared with the solid core wire it replaced. Just make sure you keep any conduit and crimp restrictions in mind if you change sizes.

[Mark Gulbrandsen]

Welding supply places always stock a number of different gauges of that wire. You can also get Tweeco twist lock in-line connectors for the cable. I had it on all of my rental stuff. Saves time on setup and tear down...

[John Eickhof]

first, remeber if you are running dc wire size will be larger, (ie 25a at 32v = #4 awg) welding cable is fine for flexibility, but the neoprene insulation is not very suitable for high ambient temps. the wire you want to replace is most likely impregnated cotton insulation and resembles asbestos but it really is not, it is a gypsum compound compound and even if frayed it is non hazardous. i would stay with original. plus the copper quality is far superior to todays wire. not toi orget authenticity. you can get teflon and fiberglass jacketed wire wire but it is usually very stiff due to strand count. you can still but new cotton braid wire from westpenn and other mfrs but it is sold in 1000ft rolls and quite expensive. use Kierney clamp type lugs for authenticity or solder lugs.

[Dave Macaulay]

Have you confirmed that it is asbestos?
Welding cable should be good for many years if the lamp is only used rarely for demos if at all.
There is UV resistant wire sleeve available if that's critical, and Teflon jacketed wire is not bothered by UV.

[Mark Gulbrandsen]

John, the actual wire size depends on the length. In the Chicago Theater the generators were 8 floors down in the basement. In that case they had to use buss bar... also, most welding supply places sell the rubber cable by the foot. At least in Chicago and Salt Lake City it was sold by the foot. Except for authenticity there is really no reason to use the old stuff.

[John Eickhof]

sorry mark but short lengths under 15 ft or so the voltage drop will not effect wire size as much as current load and direct current requires larger gage wire due to non collapsing current running through the wire, what is most important is conductor stranding allowing more surface area of the wire per watt running through it especially at lower dc voltages like arc lamps use, also it is still valid in the nec that min. wire gage to any projection lamp is #6 awg no matter how low the actual line current is. in AC wiring it is generally recommended to adjust wire size on lengths over 100ft as solid conductors have more voltage drop than stranded conductors. read up on the nec recommendations, also open wires will handle more current then encased wires no matter the run length. ie: in conduit or underground, etc.

[Jesse Crooks]

Thanks. I was not aware that you needed a larger gauge for DC... I was instructed to always use 14AWG for the run from the wall to to rectifier for the 18A lamps. Didn't know the requirement changed between the rectifier and the lamp.

How do you tell the difference between asbestos and gypsum impregnated wire? The equipment I'm considering replacing the wiring on is mostly from the 1910s-1930s and often has other asbestos insulation. I was under the impression that all of the wiring was asbestos. I've attached a photo of the wiring on a Power's incandescent. I think most or all of it looks like this. Some of it might be a smoother texture. I assume the insulation on the right is also asbestos (not planning to replace that).

If it was sitting in the same place forever I would leave it original, but the number of times I've already built up, broken down, and hauled around this stuff is the reason why I'm looking to replace it.

[Mark Gulbrandsen]

My first arc system was a low intensity Strong and two tube Strong rectifier circa late 1920's, a friend still has it. The wiring in the rectifier was asbestos and in good shape, so I left that intact. I put a rubber covered SO 12 gauge cable on it for AC and 4 gauge rubber covered welding cable for the DC Max current from the rectifier was 35 amps on a day with slightly high line voltage. I normally ran it at about 28 amps. It only ran one reel at a time, so was with in it's duty cycle.

[Jesse Crooks]

I'm also running Strongs, but I guess the size down from that. Mine have brackets to mount on portable Simplexes (they work on an SP and a pair of prototype portables based on the Super, and if you block them up they can work on a standard Simplex or an Edison). I have one rectifier with a similar profile that I think was for a Simplex Acme but it may be slightly more decorative than yours. And three that are boxier and lack the aesthetic touches of the older model.

[Mark Gulbrandsen]

I made that base. The lamp in my pix may be off a Simplex Acme or SP, or something similar...

[Jesse Crooks]

Here's a shot from the last demo we did for the Newtown Theatre's reopening gala in December. Had the 1920s Strong low intensity lamphouse blocked up for the 1898 Edison, on the base for a Power's No. 6. We ran Edison's footage of the San Francisco earthquake, which was the first film ever run at the theater in 1906.

[Mark Gulbrandsen]

Same lamp house!

[John Eickhof]

that wire used by strong is most likely an asbestos impregnated cotton strand wire, it is basically harmless to the user as the asbestos is applied as a liquid and is non fierous even if the insulation is frayed the hazard of asbestos transmission is very minimal if none at all, the asbestos that you should be careful of has fibers imbedded in it such as paste that was applied to steam pipes and boilers, it resembles mortar and it is the airborne fibers that are harmful. I went through this issue with some govt institutions years ago that got worried about their strong super troupers having the same wiring...finally with letters from strong and a lab it was determined the wire was harmless when used as designed. i would not mess with it, nor would i worry about using it.