Decrease font size
Increase font size
Topic Title: Working clearance to 132kV O/H line
Topic Summary:
Created On: 02 August 2012 04:32 PM
Status: Read Only
Linear : Threading : Single : Branch
Search Topic Search Topic
Topic Tools Topic Tools
View similar topics View similar topics
View topic in raw text format. Print this topic.
 02 August 2012 04:32 PM
User is offline View Users Profile Print this message


Posts: 1
Joined: 25 November 2009

Hi everyone,

I have a requirement to deliver a pre-fab building under a 132kV overhead line, I would like to know what the safe working clearance is to that line. The DNO have not been forthcoming with the information but I am getting the access road to O/H line measured, then minus the safe working clearance will help determine if I need to plan for an outage with the DNO.

Thanks in advance to anyone that can help

 02 August 2012 05:00 PM
User is offline View Users Profile Print this message


Posts: 91
Joined: 18 October 2002

I do not know the answer to this off the top of my head (not my field). However, my only comment would be that in the last few years I have come across quite a few places on my mountain bike where I have ended up cycling on tracks, with a "scarily" small distance between my head and 132kV or 275kV lines. Especially when its damp, you end up cycling under as quick as possible with your head down, trying to ignore the crackling.

So, I don't know the answer, but to be sure it is not tens of metres.

Dr. Andrew Roscoe
 02 August 2012 05:52 PM
User is offline View Users Profile Print this message


Posts: 6195
Joined: 27 December 2005

The ESQCR regulations give the minimum height of a 132kV overhead line as 6.7m. Typically, 10m is used for the minimum horizontal distance. The document you need is from the HSE, Avoidance of danger from overhead electric power lines, which is available to download from this HSE page. You will not be allowed to work using the same distances that DNOs are allowed to use, as they are trained to recognise these hazards and distances. I will therefore not be telling you the distance given in the safety rules either. The sheet produced for the agricultural industry may also be of use, and is available for download here.


 02 August 2012 05:58 PM
User is offline View Users Profile Print this message


Posts: 20745
Joined: 23 March 2004

For a 132kV line, the minimum clearance to ground is 6.7m

A safe clearance to that line for passage or working is roughly deduced from the breakdown voltage in air - about 75kV/m

I'd want at least 2m clearance from 132kV - but the line owner may have a greater distance in mind.

This has to be something that the CDM-C will be taking an interest in I suspect - so perhaps you need to persevere with the line owner.



PS - Andrew - I think 275kV is only required to have about 7.0m clearance to ground

Let the wind blow you, across a big floor.
 02 August 2012 08:51 PM
User is offline View Users Profile Print this message


Posts: 3676
Joined: 22 November 2007

When I used to ride my horse (before a little mishap) one of our favourite routes crossed under several 132KV lines routing into a primary sub.

You feel frighteningly close when the horse is 2m to the saddle plus about 1.2m of my upper body, head and hat on top. Not the time to start swinging the whip around around above your head...

Like Andrew said, they crackle and pop lovely when it's wet

 07 August 2012 11:43 PM
User is offline View Users Profile Print this message


Posts: 2
Joined: 12 June 2002

I would continue to seek guidance from the DNO. Further to other comments, OHL's also have other factors that should be taken into consideration when obtaining height measurements of lines. The DNO's have this info also.
 11 August 2012 07:54 PM
User is offline View Users Profile Print this message


Posts: 34
Joined: 10 July 2009

2.9m for 132kV and 3.9m for 275kV.
 21 October 2012 04:06 AM
User is offline View Users Profile Print this message


Posts: 2
Joined: 11 October 2012

for 132kV typically it's 6.7m for vertial clearance.
However, you have to take into consideration physical separation between conductors and the structure. Depending on the design of the structures supporting the conductors, the safety clearance should take the magnitude of swing of conductors due to wind deflection into account.

See Also:

FuseTalk Standard Edition v3.2 - © 1999-2016 FuseTalk Inc. All rights reserved.