What are these wires under a flat roof?
severaltypesofnerd
| Posted in General Questions on
I’m looking at a 1920’s flat tar & gravel roof, with a 3 foot attic below.
Laced through the attic are bare #14 copper wires running edge to edge, all in the same direction. All wired with ceramic tubes & knobs, exactly as knob & tube wiring.
Most of the runs just end at the outside walls, at a knob. Spacing is every 4 feet or so.
It’s got to be some sort of static electricity collector. Can’t be a lightning rod because if it worked the building would catch fire. Thoughts? Ever seen this?
https://www.nps.gov/orgs/1739/upload/preservation-brief-50-lightning-protection.pdf
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Replies
It may be someone's old ham radio antenna. Can you provide any more detail about the layout? Does it do anything "interesting" at the ends or in the middle of the runs?
Bill
The layout is murky as I have not crawled the whole thing.
At one corner of the attic the wires dive into a wall.
Most of the wires terminate at a ceramic knob, nothing interesting.
Given the access issues it must have been done before the lath & plaster ceiling was installed in the 1920's. It's a 3 story building in an urban area, with low (but not zero) lightning strikes.
I think it may be an old shortwave antenna. If you have two roughly equal "halves" in the attic, and they go down into the same wall with the spacing between them within the wall kept relatively constant, it was probably an old antenna with a balanced feed. That would be my guess here. If only one end goes into the wall, it would be an "end fed" antenna. Both were commonly used by ham radio people back in the day (and still are, but not usually in attics like this).
Old knob and tube electrical wiring typically used wire insulated with rubber and a cloth outer braided covering. I never saw bare wire used. You would typically have some taps off the runs too, and you don't seem to have that. I doubt this was electrical wiring. This wiring doesn't appear to be run in the usual "two parallel conductors" way that knob and tube wiring would have been installed.
I don't think this was lightning protection, either, since those systems are nearly always installed entirely on the exterior of the structure, and use very different materials than what you have here.
I WOULD check that nothing connects to this anywhere, but I doub't this is anything you need to worry about. I'd probably remove it if I was going to be working in the area where it's installed, otherwise I'd just leave it in place.
Bill
This antenna may well have been use with a 1920s console AM radio as they were very popular and the only instant communication at the time.
Walta
Perhaps a whole house antenna system, so everyone could get radio signals well?