Health and Safety

[chopperpete]

https://metro.co.uk/2022/01/05/gardener-killed-by-11000-volt-shock-from-powerline-as-he-cut-hedge-15870043/

 

 

Nasty....

Edited January 6, 2022 by chopperpete

[Bob_z_l]

It is sad event. Not pleasant for anyone involved. 

2 things...

1 )I can't remember the distance but think it's close on 3m for the safe distance from 11kv to avoid the "jump"

2) Complacency...always there.  The - "I've done t a 100 times before"....always a bad start to the story.

 

Risk assess yes, but complacency is the killer.

[Dan Maynard]

It is sad event. Not pleasant for anyone involved. 
2 things...
1 )I can't remember the distance but think it's close on 3m for the safe distance from 11kv to avoid the "jump"
2) Complacency...always there.  The - "I've done t a 100 times before"....always a bad start to the story.
 
Risk assess yes, but complacency is the killer.

I did UA1 basic electrical knowledge module which was enough to scare me.

3m is indeed the vicinity zone around 11kV lines, which you never breach in order to maintain the safety zone around the conductor inside. However this is only for DNO authorised people, safe systems of work, etc etc.

For everyone else, contact the DNO if you are working within 10m of the line and they will discuss and advise a safe system of work.

[devon TWiG]

this is always a very confusing subject ...safe distances ...I am pretty sure 11kv will not "jump " 3metres ,( under normal circumstances ) I think a spark plug takes 25kv to jump the gap ,   but I completely understand the need for extreme caution around electric lines , but if they are grossly overstated then they will be ignored to some extent by some people .  Look at a pylon for example 400kv yet the metal superstucture of the pylon is only about 3metres from the conductors , Watch a lorry  on a road go under 11kv lines with only a couple of metres clearance , I have worked on line clearance in the past and never really liked being near the conductors ...live, or made dead , and it can be very hard to judge distances esp when in tree adjacent to conductors ... not sure 10 metres safe distance  is possible as 11 kv wires are only about  6-7 metres above ground level , so grass cutting is breaking the rules !!!

[Dan Maynard]

this is always a very confusing subject ...safe distances ...I am pretty sure 11kv will not "jump " 3metres ,( under normal circumstances ) I think a spark plug takes 25kv to jump the gap ,   but I completely understand the need for extreme caution around electric lines , but if they are grossly overstated then they will be ignored to some extent by some people .  Look at a pylon for example 400kv yet the metal superstucture of the pylon is only about 3metres from the conductors , Watch a lorry  on a road go under 11kv lines with only a couple of metres clearance , I have worked on line clearance in the past and never really liked being near the conductors ...live, or made dead , and it can be very hard to judge distances esp when in tree adjacent to conductors ... not sure 10 metres safe distance  is possible as 11 kv wires are only about  6-7 metres above ground level , so grass cutting is breaking the rules !!!

You're right, it absolutely won't jump 3m. That distance is to keep you out of any danger of breaching the safety zone, which is only 1m.

 

It won't jump 1m either, that is set as a safe distance. One of the problems is that the exact distance it can jump varies, depending on things like atmospheric moisture, shape of object, etc so the rule has been set conservatively with the aim of making it apply in every situation.

 

Spark plugs take more voltage to make the jump due to higher pressure in the cylinder, modern cars may make 25kV but older ones with points much less - so this is difficult to compare as well.

 

The 10m isn't a distance to keep clear, it's the minimum distance you need to be before you can completely ignore the power lines rather than including them in your risk assessment, obviously if you're felling something taller than 10m you need to consider it when further away. It comes from HSE guidance applying to tree work, so your lawn mowing is safe.

 

"When arboricultural (aerial and ground) works are proposed within 10m (measured at ground level horizontally from below the nearest wire) of overhead power lines a risk based approach needs to be adopted. In practice this means that you should seek specialist advice and guidance from the owner of the power line (Network Operator) before undertaking any work within this distance. "

 

Working near power lines and cables

WWW.HSE.GOV.UK

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Contact with overhead power lines (OHPLs) causes fatal or severe electric shock and burn injuries.