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Pole.
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3131 Posts
Question
I am asking this on behalf of a friend. A young mum with toddlers that use the back lawn is concerned about the pole. The overhead supply comes in on A.B.C. cables and the pole being the last in the run has an earth electrode at its base. The pole is situated in a boundary hedge and the toddlers, over bare footed on the ground, can walk with 0.5 metres of the earth rod.

Are there any safety concerns here please?

Concerned of Peckham.

 
18 Replies
mapj1
3753 Posts
The danger is slightly less than that of a PME earthed lamp-post, but then you do not normally want one of those in your garden. Less because any connection is not metallic, as it would also be for say an outside tap via metal pipes, but via the earth around the rod.
The unhappy coincidence of an electrical fault that put a lot of current into the ground, and the child being optimally positioned and oriented to receive a dangerous shock, is to say the least, most unlikely. The fact that the supply is ABC also works in your favour - a single core fault will not result from a falling tree or similar - and that sort of thing does not happen on a sunny day.
Perhaps the youngsters should not be out in conditions of high wind and rain without insulating footwear, as well as waterproofs. The short of fault that would be dangerous (broken PEN) is usually fixed  or isolated PDQ, as fok notice the effects of voltages being wildly out.
It is probably less of a risk than almost everything else in the back garden, unless all plants, garden tools, trip hazards etc are removed first.  Small children have a lower shock threshold, but they also take smaller steps.
I'd not be worrying.
More of a concern if they want to do something like build a den round it would be splinters, or the wood preservatives that are quite nasty.


Mike.
 
Mike
What would your thoughts be had there been either a single phase or three phase transformer on that wooden pole? There would be separate HV & LV earths. There is such a (single phase) pole & transformer in our local cemetery at 53.187457 -3.022637 (Hawarden No.2)

Concerned of Hawarden
 
Chris Pearson
2686 Posts
The double pole one which supplies my daughter's house is just on the grass verge. I doubt that the DNO would have put it there if it presented a hazard. The smaller one which supplies step-daughter is in a field adjacent to the house. There are no piles of dead sheep at the bottom of the pole.

 
With a single phase transformer (as per the local cemetery one) connected across two 11 kV overhead lines, would there normally be much current flow to earth due to the capacitance of the HV windings to the earthed tank?
Clive
mapj1
3753 Posts
under certain situations a pole can give real trouble,  luckily that sort of thing is rare.

On a transformer there will be some current from the HV phase windings through the inter-winding capacitance that can be nanofarads.
Mike
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3131 Posts
There are no piles of dead sheep at the bottom of the pole.

 

Is that because she lives on the High Street Chris? Or do the locals immediately grab the dead sheep for a Sunday stew?😆

gkenyon
1567 Posts
I'll go for a flippant remark since it's the weekend.

Is there more of a risk in kids near 11 kV overheads growing up to become little *******s and throwing stones at the insulators until they break?
Sparkingchip
4245 Posts
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There are no piles of dead sheep at the bottom of the pole.

 

Is that because she lives on the High Street Chris? Or do the locals immediately grab the dead sheep for a Sunday stew?😆


Many years ago we did work for a High Court judge, he stopped a trial to drive home because his dogs had got out and killed some sheep, so having driven home he wrote out a very generous cheque to cover more than the value of the sheep and gave it to the farmer.

He thought that was the end of the matter having made a prompt and generous settlement, what he did not expect was that the farmer would return with all the meat neatly butchered and packed in freezer bags. The farmer actually played a blinder, the judge thought he would keep it quiet so friends and neighbours would not find out what had happened, but then he had to ask them all to put the meat in their freezers because he couldn’t get it all in his, which meant what had happened was soon the talk of the village.

 

Sparkingchip
4245 Posts
Regards the pole earth, any voltage on it will almost certainly be the same as the voltage on all the earthed metal work in and around the house.
I just watched that video  scary what can happen what I want to know why didn't the substation fuses blow? 
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3131 Posts
gkenyon:
I'll go for a flippant remark since it's the weekend.

Is there more of a risk in kids near 11 kV overheads growing up to become little *******s and throwing stones at the insulators until they break?

You never did? Did you?

Z.

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3131 Posts
Sparkingchip:
Regards the pole earth, any voltage on it will almost certainly be the same as the voltage on all the earthed metal work in and around the house.

But the young mum is more concerned about the stray Voltages roaming about on her lawn, under the pole,  near the end of run earth electrode, where her young children play bare footed.

Edit. Add.

Earth Electrodes Part 1 - YouTube

Z.

gkenyon
1567 Posts
Zoomup:
gkenyon:
I'll go for a flippant remark since it's the weekend.

Is there more of a risk in kids near 11 kV overheads growing up to become little *******s and throwing stones at the insulators until they break?

You never did? Did you?

Z.

No ... but probably only because there are no overheads where I grew up.

AJJewsbury
2698 Posts
under certain situations a pole can give real trouble,  luckily that sort of thing is rare.

That was impressive!
 

I just watched that video scary what can happen what I want to know why didn't the substation fuses blow?
My guess would be that it was one of the old pitch filled sealing boxes (on the end of an PILC cable) so the arcing was through something akin to carbon char rather than a nice dead short metal-to-metal of negligible impedance so the fault current was limited and likely quite short for each individual 'crackle' event.

Maybe someone's found an application for AFDDs after all....

   - Andy,
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3131 Posts
gkenyon:
Zoomup:
gkenyon:
I'll go for a flippant remark since it's the weekend.

Is there more of a risk in kids near 11 kV overheads growing up to become little *******s and throwing stones at the insulators until they break?

You never did? Did you?

Z.

No ... but probably only because there are no overheads where I grew up.

Yeh, we had to climb trees, go for bike rides or kick a tin can about as well.

Z.

Zoomup
3131 Posts
Zoomup:
There are no piles of dead sheep at the bottom of the pole.

 

Is that because she lives on the High Street Chris? Or do the locals immediately grab the dead sheep for a Sunday stew?😆

Please see 10.23 ref sheep.

https://www.bing.com/videos/search?q=youtube+at+last+the+1948+show+shepherd+sketch&docid=608030922405334673&mid=DDC68EDA0F64719EEE4FDDC68EDA0F64719EEE4F&view=detail&FORM=VIRE

Z.

I just watched that clip very funny they don't make them like that anymore

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