Why Covered Wire and Spacer Cable

[Mbrooke]

So a thing happened.

A while back several members were asking me why I believe in covered tree wire and spacer cable. So this happened today- a tree branch fell on a bare 23kv wire segment driving the main trunk line to lockout directly resulting in 1,404 outages including a dozen restaurants (McDonalds, Panera, Mom and pop), four dozen business, hundred unit apartments, and a portion of a mall. The cost of tree wire would have been offset several times over just from the lost revenue of everyone closing up early before the afternoon rush IMO.

Just my opinion on the matter.

 

[davidbeach]

Cost. Hendrix doesn’t go in for free. Somebody, aka the rate payers for the whole system, pays for it while a few benefit. Is that a good deal?

Probably a great deal for those customers, but probably not for the vast majority of customers.

Just because it is possible doesn’t mean it’s a good use of rate payer money.

I’ll see your silver lining and raise you two black clouds. - Protection Operations

 

[Mbrooke]

You musn't get power outages, or you have a generator

Depends though. If there are a lot of trees like up in the north east, many more customers benefit. I can understand why its none existent in the Midwest and California, but in places like New Jersey and Connecticut where foliage is dense utilities have found success in making the switch to tree wire. Although they have some of the highest rates in the nation so that might also have something to do with it.

 

[davidbeach]

Still has to be paid for, even if many customers might benefit.

I’ll see your silver lining and raise you two black clouds. - Protection Operations

 

[Mbrooke]

That is true, there is no such thing as free lunch as I've been told. And have come to find out more than once.

 

[stevenal]

Note that the spacer wire cable covering is not full insulation. My concern is that the same tree will take the cable to the ground where it will remain energized and undetected.

 

[cranky108]

Some people would say underground the lines. And in some places the customers approved the higher cost of undergrounding.

We have many trees, and no spacer cables. Just more than 50% underground lines.

 

[davidbeach]

As Steve mentioned, spacer cable is only covered, not insulated. Sort of like tree wire in that regard. Tree wire in the air is a wonderful thing. But there's about nothing worse than tree wire on the ground. As with many things, it's a case of being careful about what one wishes for.

I’ll see your silver lining and raise you two black clouds. - Protection Operations

 

[Mbrooke]

I have to agree here David. In air it doesn't short out when a tree branch briefly touches it. However, you would be correct that it tends to come down and stay energized.

Personally I think this is why the "stay away from powerlines" rule comes in, however I've had folks tell me this isn't enough.

 

[jghrist]

Note that the spacer wire cable covering is not full insulation. My concern is that the same tree will take the cable to the ground where it will remain energized and undetected.

This happened in my neighborhood recently. During a storm, a tree fell across three phases of a 12 kV line with covered wire outside my subdivision. This situation remained all day until I left the house, saw that the line was down over the road outside my subdivision with the conductor about three feet above the ground, holding up the tree. Someone had put barriers up to stop traffic, but no utility crews were present (there were widespread storm outages). I realized that this is the line serving my subdivision and we still had power; the line was still energized. I called in to report the energized line down, but for about ten hours, there was a very hazardous condition where pedestrians could easily have been electrocuted.

 

[waross]

Some utilities find tree trimming to be more cost effective.
And if the tree is on private property, the homeowner may be encouraged to trim his trees.
I have paid to trim my trees away from power lines at two different houses.


Bill
--------------------
Ohm's law
Not just a good idea;
It's the LAW!