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#1 Posted : 11 April 2007 20:26:00(UTC)
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Posted By JohnZamo
Can somebody please point me to the right regulations for the minimum safety distances from exposed and energized High Voltage Plant and Equipment for Non-qualified HV Employees i.e. normal workforce say in a Power Station etc as I can't find anything concrete in UK regulations Thanks
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#2 Posted : 12 April 2007 14:09:00(UTC)
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Posted By Paul A. Swift
If you want to e-mail / provide me with some additional details, I may be able to point you in the right direction.
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#3 Posted : 13 April 2007 14:29:00(UTC)
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Posted By Bob Youel

The actual distance that electricity can 'jump' to earth is far greater than most people think and that many guides indicate -

Working with the CEGB [as it was] re the national grid & power production I found that there were many occasions where the way electricity acted upon occasion surprised all but the most senior electrical engineers

Try the HSE 'help line' for specialist help

I would advise that strong PTW systems and good training is in place
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#4 Posted : 25 April 2007 21:23:00(UTC)
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Posted By Garry Homer
Minimum safety distances are those deemed to be necessary by the operators of the electrical plant. Each electricity company has its own rules, although these tend to follow a nationally agreed format, or they did when I worked for them. So you need to talk to them.

If you are working in an environment where inexperience could lead to an accident, then you should not be there, or, you should be directly supervised by a suitably authorised electricity company employee. Normally with a safe work zone clearly distinguished with ropes and warning flags including a safe access route that is similarly roped off. All other equipment that is outside the roped off area and adjacent to the safe zone should be labelled as LIVE. Just in case you forget which side of the rope you are working from! Green flags should be hanging on the safe side of the rope at every support. All other access routes into the site should be locked closed and labelled as Danger Live.

All this should be explained in a formal induction.

If you are expected to provide your own safety supervision this should not happen without your staff attending the electricity company training courses, passing the course and being formally assessed by a senior engineer from the electricity company who puts his name on a competency certificate that says your people are good enough - the signing of these certificates is very uncomfortable!

The company safety rules normally have drawings of typical plant arrangements and the distances they want you work outside of. The type of work being undertaken will also cause other safety distances to be applied, ie, when carrying long items into the work zone etc.

Work Safe.

Garry Homer
Director
Electromagnetic Surveys Ltd
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#5 Posted : 26 April 2007 08:40:00(UTC)
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Posted By Colin Dobson
John

I work in a power station and we work on the basis of a minimum distance of 3.1 metres from exposed HV conductors on 400kV systems, although voltages have been known to be induced in metal equipment i.e. MEWP's well in excess of this especially in damp or wet conditions.

If you want a copy of all distances for the different HV values drop me an email and I will forward the document on.

Regards

Colin
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#6 Posted : 21 June 2007 21:14:00(UTC)
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Posted By JohnZamo
Hi Chaps

Thanks for your replies, as I suspected there doesnt seem to be anything clear and standard for, how can each company have different sets of rules, strange when I just read on HSE web site that Electricity kills about 25 people a year, as Bob said I have personally seen where 11KV jumped across over 4 feet to a better earth after it traveled up a whole load of pipework, and Garry I do have experience in Power Stations 23 yrs in Malta and 3 yrs in UK.
Don't know if this quote looks familiar to any of you, this is taken from the then Malta Government Electricity Board Generation Safety Rules printed in the 60's or early 70's

Work on Sub-stations and Switching Stations containing exposed live conductors

GE 1 Unless the whole equipment is dead the section which is being made dead for work to be carried out shall be marked or delimited, as far as possible, by use of barriers, notice boards or roping, arranged so that the minimum clearance from the nearest conductor in air to ground level or to platform or access way which may be used when that conductor is live shall be :-

Rated Voltage Clearance
Not exceeding 6.6 kV. 8 ft. 5 ins.
Exceeding 6.6 kV. But not exceeding 11 kV. 8 ft. 6 ins.
Exceeding 11 kV. But not exceeding 22 kV. 8 ft 8 ins.

The word "platform" is used in the ordinarily accepted sense and does not include the tops of transformers, circuit breakers, or other apparatus.

The area to be marked or delimited at ground level shall only be that in which the work is to be carried out.

If the work cannot be carried out without leaving ground level, or such platforms or access ways, the above minimum clearances shall be obtained from the nearest live conductor to the points at which work is being carried out.

If the work is such that these clearances are not sufficient to avoid danger, other suitable arrangements shall be made to provide the requisite degree of safety.

The section shall be distinguished by green flags by day or green lights by night, fixed in prominent positions, supplemented by Danger Notices attached to adjoining High Voltage Apparatus or sections.

Thought maybe something like this exists as the then Malta was under British Rule and all regulations used to reflect those present then in the UK. But I can't find this anywhere.
I also believe there are different distances for Qualified HV personnel like Linesmen Jointers etc. and Non Qualified i.e. like those workers that paint the gates to your Air Insulated 11KV transformer as this CAL/OSHA document suggests. http://www.ehs.uci.edu/p...ty/hvoltageAppendixD.pdf
Thanks all in advance for any information you can provide in light of what I just added.

Regards

John


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#7 Posted : 25 June 2007 13:45:00(UTC)
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Posted By Garry Homer
John

The National Grid have plublished safety rules at:

http://www.nationalgrid..../SafetyRulesHandbook.pdf

These do not show a specific category for 11kV and I suspect this is because there is no real need, ie, 33kV and below is sufficient.

These rules could be the nationally approved version that will also be used by all the electricity companies.

Well they look very similar to the ones I once had to assess.

Regards

Garry

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