Re: OT Overhead power wires....

[charles]

What goes into the "box on pole" will b well over 1000v. What comes out of the box should be 240v - normal mains that you find in the house.

[Jonno]

jim scribbled

> I am supplied with electric via a "box on pole" then 3 overhead > wires (2 black covering) 1 verdigris Green (bare?). > > Two of the 3 wires to the house appear to be jumpered together. > > A tree surgeon is insisting it's 1000v and unsafe for him to prune > an overhanging tree. > > Where the 3 cables meet my house wall, 2 of the overhead wires > join into some thick pvc clad cable, which then goes, clipped to > wall, into house to meter etc. > The third overhead wire connects to a single "verdigris" coloured > bare solid conductor that is clipped with the pvc cable and also > makes its way to the house meter etc. > > Is it 1000v? Or is he wibbling? > > What's procedure to get the tree finished? Any costs to be aware of? > > TIA

You call the Lecci campany.

[Chris French]

Well , it will be 240V, that's how these things work.. If it was anything higher then you would need another transformer at the house end.

And anyway, the cables are sound as if they insulated, so if anything was to inadvertently touch them there would not be a problem.

We used to have an overhead supply, there was no insulation on any of the cables AFAICR, we had tog et the suppy co to put on temporary insulation when we had work done on the house and the work men would have been working near them

[Tim Streater]

What makes this geezer think it's anything *other* than 240? As has been mentioned, if it were 1kV, it would require another transformer at your house. Why does he think it's 1kV?

[charles]

If it was 3 phase then it would be 440v.

[damduck-egg]

Any reason that he might not want the job for other reasons such as a personality clash and he is just making excuses.

G.Harman

[The Natural Philosopher]

No, it will either be well below or well above,.

240V or 11KV.

[newshound]

440 volt rms between any two phases. 240 volt between any phase and neutral.

[charles]

yes, so the maximum is 440v

[The Natural Philosopher]

440V AV. Think the Peak to peak is higher than that

[Martin Brown]

It might well be if the insulation is as poor as it was in my village.

Are you on multiple phases?

I wouldn't like to bet on that. The insulation on the copper wires of our old village supply had long since perished and would drop off in strips that would arc and spark between phases in wet weather.

The new three core aluminium cable platted around a steel hawser is much more robust PVC coated and has survived tree falls across it, but not a fully laden milk tanker ploughing up its poles.

A pretty good heuristic is that thick lines that are arranged vertically on poles tend to be basic household mains whereas thinner lines horizontally on spars at the top of taller poles are 11kV or 33kV.

Round here contractors from the electricity distribution company come round every few years and drop the village off mains supply for a day in summer whilst they trim any offending trees.

I don't blame the tree surgeon for not wanting to work close to mains power lines with a chainsaw.

[newshound]

Yes, 440 volts rms. Peak factor is root 2 so for three phase peak is 622 and peak to peak is 1245, so perhaps that is where the 1000 volts came from. Not that this is meaningful, since the peaks occur at different times.

But this is surely a single phase supply, so peak is 339 and p-p, 679 volts.

[The Natural Philosopher]

Assuming its not a pole mounted 11KV substation.

Dozens of those round here

[Martin Brown]

Might not be in a rural farm house -could easily be three phase.

And rural copper cable insulation has often perished falling off in strips at the slightest provocation.

[newshound]

Oh I'm not questioning that the pruner needs to take appropriate care, just speculating on where 1 kV might have come from.

Does sound rather like an excuse for not doing the job, as someone else suggested. Surely an experienced person would know exactly what needs to be done, i.e. keeping bloody well clear of 11 kV and leaving it to the utility responsible, or for "low voltage" (whether single or three phase), getting the protective sleeves put on. And how to get it done, and whether the supplier charges for this service.

[Martin Brown]

If the trees are a threat to mains distribution cables rather than just your own private feed cable then round here NEDL come out and do it from time to time. And they always take all mains power off the entire village whilst working with a cherry picker and a chainsaw.

SOP is to isolate the section being worked on before starting.

[Vir Campestris]

Well, I would have thought that. The insurance man was worried about the wire near our thatched roof, and you'd think he'd have seen some before. The thatchers didn't give a damn. I was confident enough to reach up and give it a shake to prove it was safe to my wife!. The electricity people told us that the cable was specced safe for burial.

Andy

[Alan Dawes]

But the worry is - whose burial? :-)

Alan