As you will see from the attached photos, my son's power supply does not have an accessible cut-out. The supply is via a pyrotenax cable directly into the meter. In order to upgrade his CU it will not easily be possible to isolate the power and on initial enquiry it appears that he would be responsible for the substantial cost of upgrading the supply cable to the meter. You will also see that a second CU was installed in series with the original to feed a loft extension by a NICEIC approved contractor approx. ten years ago according to the stickers. I have no idea how safe isolation was achieved if at all. Is it not the DNO's responsiblity for the safe supply of electricity up to the meter? Would my son have been better off requesting a smart meter and putting the ball back in their court?