Connecting a Wireless Relay to Boiler

[denso13]

will there only be one live wire?

No idea, you'll have to check.

 

[oldbutnotdead]

There will probably be several cores in there that at various times will be at 240v. It wouldn't be a big surprise to find some switched neutrals in there as well (given the low quality of the install).

 

[Jetheat]

So how will I know which live and which neutral to use for the relay?

 

[ianmcd]

just follow the cable from the fused spur

 

[oldbutnotdead]

By using your meter to find a live and neutral that are permanent (ie their state does not vary whatever the timeswitch, thermostats, motorised valves and boiler are doing)
EDIT. Yeah @ianmcd is spot on, if the cable from the fcu goes direct to that wiring centre they'll be yr permanent l & n

 

[Jetheat]

My fused spur feeds about 5 wires into the junction box.
So I take it one of them is live and one is neutral, right?

i can detect a live wire.
How do I detect a neutral?

JH

 

[oldbutnotdead]

My fused spur feeds about 5 wires into the junction box.

Unlikely. Most likely is there is one 3-core flex from the FCU to the wiring centre, that 3 core then feeds several other cables. Identify the 3 core cable that is coming from the FCU and those are your permanent live, ,neutral and earth.

So I take it one of them is live and one is neutral, right?

i can detect a live wire.
How do I detect a neutral?

JH

Oh ffs.
Neutral is at zero potential (more or less- there may be 2 or 3 volts on the neutral when referenced to earth).
So, you determine your LIVE by referencing it to earth (240v, hurrah).
Now you have a known live. You have a wire that you think might be neutral. Is the insulation colour green and yellow (or is it bare copper in twin and earth)? If YES then it is almost certainly EARTH and must not be used for anything else. If no and your known live is at 240v relative to it then it is a neutral.
EDIT Confirm this by referencing your suspected neutral to earth- should read between zero and 2 or 3 volts. And use your eyes.

 

[ianmcd]

My fused spur feeds about 5 wires into the junction box.
So I take it one of them is live and one is neutral, right?

i can detect a live wire.
How do I detect a neutral?

JH

you said you had a multi-meter so use it, this post has got to be a wind up

 

[Jetheat]

PLEASE ENGAGE THE SERVICES OF A QUALIFIED ELECTRICIAN