Back boiler wiring

[gjj1981]

Hi all,

I am trying to change the programmer for my back boiler

I have a cold water tank in the loft, a smaller tank for CH, an immersion tank and a back boiler.

The wiring coming from the boiler area are as follows:

1 x Earth
1 x neutral
3 x Live

Could someone explain why 3 lives?

Thanks in advance

 

[AWheating]

whats the manufacturers instructions tell you? there are many boilers fitted to many types of system that are wired in different ways tbh. prob best to get a heating engineer in.

most clocks have a guide to help change them.

 

[Ermintrude]

Should have gone like for like. One is from spur one is for pump and one for bbu, check it all before u juice up