I ony give this low confidence siply because the FR term 'poste' is so general and used in so many different ways, it is difficult to know for sure the best translation without knowing the actual form it takes in any given situation: it basically means 'the place where something happens / is done' — and here, that 'something' is the 'coupure' of the incoming HV supply (one may assume). In EN, we would probably more usually describe it on the basis of 'what it houses' — in this case, whatever it is that is used to provide this 'coupure'; again, without more specific information, we need to find a word for 'devices that provide "coupure"' — and without more information to clarify, we can reasonably assume this would be a 'breaker', or perhaps more apporpriately, an 'isolator'.

When messing around with high voltages, there are often quite impressive sparks, hence why there might be a fire risk and thus why asbestos might be expected to be found.

A whole other question arises as to what they mean by 'HT' — according to the function, this terms is relative and may be used in different ways; we don't have enough context to do anything other than stick to the literal translation HT > HV — even though, technically, this voltage may not be quite as 'high' as that would normally imply!

In cases like this, you may find it useful to collaborate on your project with another, technical translator; I work like this with a umber of colleagues who are legal translators, but get me to deal with the technical bits for them; it is a safer bet than trying to do it term-by-term, as one really needs to get a whole picture of the overall context.

Another possibility.