Done a beling gas hob installation for a friend. I am connecting it using 15mm rigid copper and have included an isolating cock. What baffles me here is that supplied in the kit with the hob to connect to the gas pipe you get an the female threaded elbow which connects to the nut on the appliance (using 1 x green fibre washer) and then two possible brass connectors to go onto the male thread of this elbow, one which allows 15mm copper to be connected using compression and one which I think is male threaded 1/2inch. However, you can't just use the compression type on its own because the female thread on this one is too deep for the male thread on the elbow to screw all the way in. Hence, you have to use all the supplied fitted for connection to copper, which needs 3 fibre washers. The pack only has 2 fibre washers in. My conclusion: a fibre washer is missing! Just wondering whether this is the case or whether ive got mixed up somewhere. ps NO i am not Corgi Registered but I take my ACS in a month from now.