Sparky

Hi, I am about to wire in a Time Guard FST17A SupplyMaster 7 day fused spur timeswitch to control my immersion heater. This is also a double pole switch therefore negating the need for a separate double pole switch within the circuit. My question is regarding earth continuity. All previous controllers I have fitted had an earth continuity link but this one dose not. This one only has a live and neutral load in with a live and neutral switched out. Now I am using plastic dry lining back boxes which do not need or have an earth point, however, after connecting the load in twins, the earth i