I assume you are correct in saying the council is responsible for the
street lighting. Either the Council or the electricity distribution
company would be responsible for the associated connections.
It would be quite reasonable to ask the Council in the first instance
to make the connections safe for your reasonable repair work either by
relocating, using replacing with all-insulated connections or
covering. If any easement exists, it should provide for just that. If
the Council claims that the distribution company is responsible, then
the company should be approached. They should be quite used to that
sort of request.
It may be, however, that they may only be responsible for the
immediate area of attachment and any lines on your property. If
electricity lines run along the right of way, covering for safety, etc
so your builder can erect scaffold may be at your cost.