I have a switched fused spur in conservatory, the fuse has gone and it needs changing. Do I need to switched off everything in house at the main fuse box, or is it enough to simply switch off the fused spur in conservatory? I have an old fuse box under stairs and it is only on/off switch, not one of these fancy modern ones. It works. Also if I need to switch off at fuse box under stairs, what will happen to boiler? Will I need to call out gas engineers to sort boiler or will it just reset itself?