Sorry, I have no idea about the laws in Oman Valsi, which is showing as your profile location. Is it a UK law / regs question or one with regard to laws & regs in Oman?

The relevant UK legislation would be the Electricity at Work Regulations 1989, made under the Health & Safety at Work Act 1974, along with a few others that you could throw into the mix, & some standards which are used as guidance. This has nothing specific about conductive ladders. However, it does preclude work on or around live conductors, and, it will refer much to risk assessment. What concerns you about the switch rooms with regard to conductive ladders? Have you exposed live parts?

Safety Man - I agree 100% with you that is why I need to find the law that proves this and specifically mentions about insulated ladders: The Electricity at Work 1989: What is work equipment? Regulation 14 Work on or near live conductors (c) the use of suitable tools, including insulated tools, equipment and protective clothing (see also regulation 4(4)); Insulated equipment - I know it also includes ladders, but I need the exact word. Thank you

The thing is, if you can contact it with a ladder, you may well be able to touch it by hand. Therefore, other suitable precautions are required. It is better to use insulated ladders, however if the switch room has been built since the 70's it is unlikely to have any accessible live parts. I've worked on a few. Now if you need to use an insulated ladder, because there are exposed live parts you can contact with the ladder, then once you have ascended said ladder then there is every chance these parts are even more accessible. Plus you need to be very wary of seperation distances with HV. At 400V 3ph, you will not get any gap jumping arcing, once you move to HV, then you can easily get gaps jumped by an arc. Now an insulated ladder may just put the user within the distance an arc can jump, are the ladders "guaranteed" to provide adequate insulation against HV? Could the arc jump from source to person, to ground, e.g. adjacent earthed electrical enclosure? I don't think that you will find a law in the UK that states insulated ladders are required. As Safety Man 1 says, you, need, to understand, these environments. It will be down to you RAMS. Or, simply shut it all down before working, not so easy, & not always necessary.

Valsi You need to revert to the relevant Electrical Safety Rules, depending who the transmission system operator is. The use of any tool, plant or piece of equipment will be covered in the safety rules and associate operational standards and instructions. We operate the transmission system in Ireland, North & South so have to comply with the requirements of the Electricity Supply Board (ESB) Rules in Ireland and the Northern Ireland Electricity Rules north of the border. But even then the activity to which the ladder relates will be subject to specific risk assessment considering safety distances, work position, adjacent live apparatus etc. Jonty