hi all, was asked to do 2nd fix on a loft conversion for a builder. the builder had done the 1st fix, so before all the work i had checked the cables and the quality of the work tested each circuit it seemed in good order. There are 3 dicon smoke alarms in the property which the builder supplied there all interlinked correctly using 1.5mm 3 core twin and earth cable. On the day of 2nd fix the builder was using a wallpaper remover steamer so it kept setting of the smoke alarms so disconnected them and left them there when after a week got phone call to say they do not go off, went had a local discovered downstairs smoke alarm faulty so asked him to replace it, so he did and changed it just plugged it in as they are with battery connected correctly, when the same day got phone call not going off went down checked wiring fine voltage fine no smoke no heat nothing even took out the interlink cable but let live and neutral go through and after 10 minutes still kept going off the set again then goes off again what could it be any help? cheers