Triplex burnt in half ????

[maradcliff]

There is an old barn on my farm that needs serious repair and one of those projects that I am always planning to get to, but never do.

Anyhow, I went out to the pasture today and was rather shocked when I found the overhead triplex to that barn was nearly touching the ground. On closer inspection, I found that of the 3 wires, only one of the hot wires was still attached to the barn, and was hanging by the service entrance head that was pulled off the building. The neutral cable, and other hot wire was just dangling in a tree.

I shut off the main disconnect and had to do some tree trimming to finally get to the wire. What I found was a spot where both the neutral wire and the hot wire were melted at that spot, which is about

10 feet from the old barn. The 3rd wire, (still attached one), had a little burn on the insulation, although not down to the bare wire.

Because there is no way to shut off the power to this one wire, I just temporarily capped the end of the hot wire and propped a 12 foot 2x6 under the center of it, to keep some of the weight off and keep if off the ground. Tomorrow I will (somehow) reattach it, or just remove it, since it's not really needed.

Anyhow, I am puzzled how, or why it burned at that spot????? It's been there for years. Although it's not used, it's been live, and did not have a tree or anything else fall on it, nor did we have any wind storms lately. Why would it burn thru, and not blow the main breaker? This has me puzzled. Even if there was a little nick in the insulation on the hot wire, why would it contact the neutral for no apparent reason? I should note that the break occurred in the branches of that tree. I do not see any burn spots of the tree, even after I did some serious trimming on it. Is it possible that the tree got wet (we just had a lot of rain), and the tree served as a short? That's all I can figure. I should note also, that the wire is not rubbed bare, like a tree branch was rubbing, it just burned cleanly in half, both the neutral and that one hot wire. I just find this real odd.

Mark

[SQLit]

You shut off the main disconnect and there is still power on the wire?

Call a pro immediately. Something is not correct.

A original defect in the wire could have slowly worn through. There is a hundred things that I can think of that MIGHT cause this problem over time.

You never noticed a tripped or blown circuit breaker?

[Duane Bozarth]

[e-mail] wrote: ....a long story about an old supply that shorted out for some reason...

There's absolutely no way to know what actually happened (or even when, apparently). It could just as easily been some critter got across the two lines which happened to have a bare spot from simply years of aging--most of the really old overhead wires on our place are almost bare simply from having been hanging there for 50 years or so...

If you have a disconnect on the pole but one phase isn't cut off, sounds like something ain't right...

Whatever you do, be careful -- sounds like you're playing around w/ a service entrance w/o having proper equipment if you can't clearly disconnect it -- not a smart idea imo.

[David Martel]

marad,

You've ruled out windstorms but make no mention of lightning. If the barn is old and in bad shape it's possible that the insulation on the wires is also old and in bad shape. From your mention of trees and branches you suggest that no one has been maintaining this service line. I don't think that the breaker on a line transformer is intended to protect your service lines. You should have the power company take a look, and replace or remove this service line.

Good luck, Dave M.

[maradcliff]

First off, there IS a disconnect. There is a 200A pull out cartridge fuse for the whole farm. and that disconnects EVERYTHING. I am not sure what I said to indicate that one side of the line is still live. It IS NOT live when I pull that fuse block. I think people are confused because I said that one wire remained ATTACHED to the service head (one of the hots), but the other hot and the neutral burned in half. Of course the neutral is the one that carries all the weight, so when that broke, the entrance head got pulled off the building. (not a big deal, a screw will fix that).

As for the cause of this problem, I think I answered my own question today. That 3rd wire (the one that was still attached), was worn down to the bare wire thru the insulation. I did not notice that yesterday because that wire was a little too high for me to reach from the ground. Today I got the step ladder out so I could splice the neutral to a new piece. I now think the triples was simply worn from rubbing against that tree. I chopped the tree down today, so that problem is gone.

I an only attaching the neutral to the insulator, and will just cap the hot wires off where they would attach to the entrance head. I plan to rebuild that old barn, but for now, I'd rather not have power to that building. The rest of the triplex looks fine, but the wires (old cloth covered cable type with neutral wrapped around the outside), looks pretty crappy. I will not go on a 35 foot pole, (too high for me), so re-attaching the neutral to the old barn, and capping off the hots is a better option, and leaves the power over there for when I decide to rebuild that barn.