Hello, I am wiring a sub main to my detached garage. I am doing this under a Building Notice with a Building Control appointed inspection through an approved contractor company. The approved company provide the inspection and test, but are not there to provide advice. Hence, would appreciate your thoughts. I have been looking at how I will connect my sub main to the supply. I currently have a DNO box containing the incoming feed, main fuse and a meter. This is within an open to air porch. The tails from the meter pass directly to a second box below with a 100amp Proteus DP breaker. The two boxes are butted up together. The output from the breaker goes into 25mm2 SWA that then progresses to the main house consumer unit elsewhere. My original plan was to take the output from the breaker, split it with Henley blocks, then feed a second breaker feeding the new sub main. However, there simply is not the room within the box to do this. The best solution would be for a larger box beneath the DNO box. To do that requires power off. I have two choices for that, pull the main fuse or use a single pole isolator that is built into the meter (Ampy 5258K).
I could request the DNO pull the main fuse ( would they do that for someone doing it DIY under a Building Notice?). However, I like to take my time on this sort of thing and do not want a short time slot to get it all done. I do not want to pull the main fuse myself and appreciate that I am not allowed to. That leaves me with the built in isolator? would you do this using that? whats the risk?
