Those round things are insulators. By inference then the insulators are insulating bare wire from the edge of the chimney etc. I wouldn't get too close to them to be honest. Like it or not 240 volts AC can kill.
IME electricity companies dislike the added workload of form-filling and attending inquests after a fatal accident, and are very willing to make the cables safe before building work starts.
This often is done by adding insulating plastic covers over the wires and terminals.
I don't think they charge.
Your DNO would be responsible. If you look at the bottom of your electricity bill it will say who, and their contact details.
Generally the service drops on open wire systems (as in your pic) are insulated but it’s more to prevent accidental contact from tree branches, etc and isn’t regarded in the same way as the insulation on say meter tails. Have you got a better pic of the cable coming down the wall? Cant tell from your pic but doesn’t look to be the best
As above though, your DNO will shroud all of that temporarily and it’s usually free.
Thanks guys....I told the customer I wasn't going to get too close to it, and would come back if they get the DNO to cover it. I did the other 3 sides. They were OK with it.
If you need to find a tradesperson to get your job done, please try our local search below,
or if you are doing it yourself you can find suppliers local to you.
Select the supplier or trade you require, enter your location to begin your search.
Please select a service and enter a location to continue...
Are you a trade or supplier? You can create your listing free at DIYnot Local