DIY Doctor UK DIY Forums

Hi

I’ve tried to wire in my nest e heat link and remove my old Drayton SCR Digistat which controls my Gloworm Ultimate boiler.

The wiring currently has the Drayton with a live and neutral.
Port 1 according to Drayton is Common and Port 3 is Call.

The person who previously wired it in used an Earth lead to 3 but wrapped it in another tape to change the colour.

It has no Earth connected as it’s currently double insulated.

I wired 1 into C and 3 into NO and terminal capped off the live and neutral.

Switched it back on and the 3A fuse in the spur blew.

Any ideas why please? It appears to wired correctly but I don’t understand why this happened.

Many thanks in advance!

The instructions I can find for the Drayton has N/O and Com so you need to find out what 1 and 3 is, as you say seems wrong, fuse should not have blown.

You should have an earth even it class II just not used, 1966 the rules changed and earth has to be taken to any fixed appliance even it not used, only exception is ceiling rose to bulb holder.

The Gloworm Ultimate can use 24 volt 230 volt or a bus connection, and so can Nest e, as to if the bus on the Glowworm is Opentherm I don't know.