Club 80-90 Forums

Got a strange query - thought about asking on an electrical forum but there is a few on here.

My central heating controller has broken and I'm replacing it. Looking at the current wiring I've got a very strange setup.

From the main Live feed I have a brown live AND an earth into the same terminal!!!

I have never touched this wiring and I've been in the house for 13 years - the central heating has always worked and I'm still alive. looking at the wiring instructions for the old and new controller it does not mention putting the earth in the live terminal - which even a electrics numpty like me I know is not right.

What harm can it do having the earth in the live??

When I do fit the new controller I shall put the earth in the earth terminal

do you know where the cable goes that has the earth in as i have seen this done many times where they need a extra live/switch wire ,they use the earth cable (sometimes flag it with red/brown)
would get it check out thou mate before you change it

lee

old central heating will be wired with ring or lighting wire rather than dedicated central heating wiring loom best check to see what's going where before rewiring it, thermostats are wired weird and lots of sparks had there own way of doing them using as few additional cable runs as possible and if there was no red single core at the time then use some green and yellow as long as it works and the job gets done,

hi.
just done this myself, had a right mish mash of colours and wires.

i drew a schematic of what i had............left it there and wired the new controller in and a new junction box. now works fine.
as said above i think they just used to use any old bits of wire they had around.
basically you only have to re new the wires from the contoller to the existing feeds from old controller(simplesssssss)

good luck
verat25(cardiff)

For some odd reason, cental heating wires come in all colours, ie- pink could be live while orange is earth etc(depending on the maker). you may need a schematic diagram to figure it all out... its a pain, but there is no common pattern

interesting stuff guys, thanks. I shall go and trace the run of the earth wire first. Then I'll draw up a schematic and post it up here. I think the earth wire goes to the pump with the two live wires.

what programmer have you got? as most have a universal backplate, meaning you dont touch the wiring. I'm changing these on a day to day basis. Unless its a very old programmer you can just change the front.
Don't worry about the colour of the wires, most plumbers are colour blind! If it was working before, the wirings ok. Don't get to involved chasing the wiring, as you can end up pulling a wire out and having no idea where it popped out from!
Let me know what programmer you got, and i'll tell you if you can leave the backplate on
Lloyd

Thanks Lloyd.

The old controller is a Randall 103

The new one is a Danfoss TS715

I did trace the earth wire that was plugged into the live - along with two brown wires. It leads to the central heating pump and goes into the earth terminal on it.

i was thinking when I change the controllers over I'll put that wire into the earth terminal on the controller.

Shall I tell you the current wiring setup?

Randall 103 is a bit of a one off controller, would be a lot easier for you to get the same controller, make it an easy change for you. Live wire going to pump earth is a bit odd, should blow the fuse. Are you sure the other two brown wires aren't earths as well? Have you got a multi meter? You can ring me tomorrow if you like, just PM me for my number.