Swapping mid position valve

[The Medway Handyman]

Swapping a Sunvic SD 2701 mid position valve for a Honeywell V4073A.

Sunvic has 4 wires; blue, grey, orange & white.

Honeywell has 5 wires; blue, grey, orange, white & earth.

Wires from wiring centre, via junction box are brown, blue, black & earth. I'm guessing it's not the correct cable & the earth is being used for something else.

Connections are (wiring centre to valve); earth to white, blue to blue, brown to orange, black to grey.

What do I do with the spare earth wire?

Or do I need to investigate the wiring centre?

[Owain]

The earth wire is not spare. It MUST be connected to the circuit protective conductor.

If the cpc in the existing cable is being used for another purpose it MUST be disconnected from whatever it's being used for, and connected to earth. An additional/new cable (with cpc) MUST be run in if the number of cores in existing is inadequate.

The cpc must be tested for continuity back to the main earth terminal (MET).

Owain

[The Medway Handyman]

When I say spare earth I mean spare green/yellow. The green/yellow is connected to the white on the actuator. In the wiring centre its connected to a green/yellow from the RF room stat. Neither are connected to the earth from the mains input.

I suspect the Sunvice was double insulated & the Honeywell isn't?

And that 'any old' cable has been used in the past.

Point taken re the earth, that can be easily done.

[Owain]

It'll all have to be rewired properly, then.

Probably done by a lead-basher ...

Owain

[The Medway Handyman]

Checked it out & the Sunvic is DI, Honeywell isn't.

Indeed, bastard! He had used a junction box & some 3 core & earth, using the green/yellow as the white.

All re wired & earthed now.

Thanks mate.