Heating thermostat no wired up with 3 phase. How do I tell which cable?

[RabbieD]

Replacing the thermostat as it wasn’t functioning. Question is how do I tell which one of these is switched live in the attached picture, new thermostat? Confusing mixture of old and new cable colours.

I’ve wired this per two cable diagram. I want to use the 3 as recommended with the Baxi combi 105e.

Old thermostat had only red wired to live and blue wired to N.

 

[Stu-B]

if you don’t know what you’re looking at then clearly you need to get someone in who does, taking 240V wiring advice from an open forum is easily misinterpreted and the mistakes can be catastrophic!
ELECTRICITY KILLS pal for the sake of a 50quid job just pick up the phone

 

[ShaunCorbs]

have you messed with the wiring in the pic? also not 3 phase

 

[exedon2]

That looks like a 3 core stat wire
Don't mess around time for a competent electrician or heating engineer

 

[Stu-B]

Also the old stat wasn’t wired up just L & N, just because that’s the colours you think are Live and Neutral doesn’t mean they are, hell I’ve seen green/yellow used as a switched live plenty of times, doesn’t mean it’s earth

 

[Aquarius]

The Baxi 105e doesn’t recommend 3 wires, it has a live and switched. What it does state isn’t 230vac switching, and if it has a neutral to be wired as per their diagram. It might be easy enough to add a neutral wire, run use battery type which doesn’t require one.