Published: 11 August 2008
Category: Q&A
Our Voltimum Experts answer your questions on a daily basis in our Technical Expertise area. This one, about the colour that machine isolator supply cables should be, is answered by SELECT:
Question: I have received a request from our EHS Department to colour-code orange the supply side cables of a machine isolator in order to identify them as being permanently live. I have questioned this because, as far as I am aware, this is not required under any electrical regulation. I have also pointed out that, if any maintenance work requires to be carried out, the equipment should be isolated by an electrically competent person who would be fully aware that the supply side would be live and advise other personnel of this fact. Is this correct? Please advise…
Answer: Conductors should be identified in accordance with Table 51 in BS 7671, three-phase line conductors to harmonised cable core colours being brown, black and grey. The colour orange would NOT meet this requirement.
Before gaining access to live parts of a machine, the isolating switch would require to be switched off. The incoming terminals at the isolator should be shrouded; the shroud bearing a warning that it covers live terminals.
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