Thermostat wiring, switched live still partially live !

[Gavinchess]

Hi all, trying to install Honeywell T4 thermostat to replace my old dial type.
there are 4 wires and i believe they are .....

Red - permanent live
yellow - switched live
blue - neutral
green/yellow - earth

I realise I don't need neutral and earth and will isolate them.
But the switched live is still showing 50-60 volts when the old thermostat is turned to low and and 240 volts when switched to high. Is it normal for some volts to still be present in the switched live when it is effectively off ?

Thanks, Gavin.

 

[SimonH2]

What's at the other end of the cable ?
Some systems - such as Y-plan - can cause a small voltage to appear on control lines when you might expect that line to be "disconnected".

 

[ericmark]

As said Y Plan the mid position valve

can cause some odd voltages due to internal components.