Power line safety procedures

[CobyRupert]

Even if you know a power line is de-energized and down, don't assume it will stay that way even if the power company has not repaired a downed line. Many people have generators now and some may not know how to disconnect their wiring from the power system. Feeding 240v through a transformer produces primary voltage through that transform and back through the system. So, if a primary line is cut and down, don't assume the "load" side is de-energized even though the source side is.

This is true and is the reason given on why proper installation and isolation (transfer) of home generators is required (i.e. to protect utiltiy line-men who may be working on the primary line that they think is disconnected from the utility source from being zapped by Harry Homeowner's 5KW generator that he has hooked through his dryer outlet)

....but, in order for this to be true, Harry Homeowner's 5kW generator would have to be supplying that whole section of the disconnected grid (his neighborhood and beyond). His generator would stall and/or trip out way beforehand. Now, if only he (and maybe just a couple of neighbors) are without power, and his genny can power them, then maybe the danger is real.

 

[kco]

A valid point regarding stalling out the generator. However, the risk is more likely in rural areas where the tap in question may have few farms. There is no assurance that the utility's open switch is the only open spot in the circuit. Every few years trees take down a section of the tap feeding my place plus about 20 others.

Just this summer I heard a fuse blow. It sounds like a shotgun. Our power was still on. The lineman patrol habit in me still makes me want to investigate when our power goes out. I found the blown switch on the neighbour's tap one half mile from here. The total length of his tap is about 2 miles and it serves just he and his son's place. He actually owns that line and is responsible for outages. I patrolled his line and could not see the problem, but I suspect it was a tree contact in the 1/2 mile section through trees.

I went to the house but there was nobody home or at his son's. So I went to their daughter's house who is on our main tap and told her. The home owners were away for a day or two but she got hold of them so they could arrange repairs. Otherwise they may have lost frozen food, etc. They would have to arrange with a local contractor to clear the fault and replace the fuse.

 

[PILOON]

Wires going to a residence are 220 volts with one neutral and the other 2 being live with 110 in each.
Modern wiring is plastic coated being well insulated as such on each 110 side.
That all being so with MODERN installations, older ones often had cotton covered 110 sides that frayed and often shedded the protective sleeve (insulation).
The older cotton stuff is scary to work around but not the newer style.
Now this is only for those drop lines to a home, not the lines that go pole to pole as they also have some very high voltages in the mix.

In a practical sense you could actually lean a metal ladder onto a home drop line without shorting but I would not suggest trying that.

 

[buickanddeere]

We had a tree fall on our power lines feeding our yard, it was blocking the driveway and the tree was just leaning against the line. We called the power company and they said "there is storm damage in the south and we can't get a truck to you for 2 weeks at least." Well it's a good think the loader tractor has 6 rubber tires cause we couldn't stay blocked in at the yard for two weeks. Just picked it up with the loader and pushed it off.

Hey bud that is one of the most foolish actions that I have heard of for a long time. A couple hundred feet of nylon rope would have been better.
The "insulation" provided by rubber tire's is of little to no value.

 

[jimmysisson]

A buddy of mine nearly 50 years ago was teaching a crew to paint HT towers. He was mid-20's. Lines were called in to be de-energized. They climbed the tower. He pointed his brush toward the top some X feet away and caught induced current from the ( weren't de-energized) lines. The fall broke his spine at T4, he remains paralyzed. Has had a full life but sure would have been better w/o that induced current. Be safe AND careful.
Jim