Hello just after a bit of advice, I've just had an oil boiler fitted in my out house the company that did it altered the electrics for it, there run 1.5mm 4 core flat cable from the existing fuse spur in the airing cupboard about 14meters to an outside junction box the armoured cable underground for about 3 meters to another outside box then about 5 meters 1.5mm 4 core flat cable to an isolator near the boiler. Just wondering if this is standard practice cable size and installation method? Or do you think I should call them back. Thanks