Hi - I have just bought a NEST 3rd gen system and I am trying to work out the wiring diagram for which wire goes where, I would be very grateful for any advice. I have attached the photo of my Potterton EP3002 program wiring harness.
You appear to have a standard Y Plan system, so you need to check that diagram in the manual. You will need to put the 2 wires that are in terminal D in a separate connector block, they will not connect to the nest. As you have so many earth wires they too will need to go in another separate connector block. Your existing terminals are:
N - neutral
L - permanent live
1 - hot water off
3 - hot water on
4 - Heating on
5 - common for heating
Look through the manual at the y plan wiring diagram and with the information above you should be able to work out what goes where, I'm not doing everything! Post back here to confirm or if you are stuck.
There is not much room in the Nest receivers I would probably fit all the wires in a box and then run a single cable to the Nest. Or install a back box in the wall to contain everything. There must be none of the coloured wires showing outside of the nest enclosure. If it starts looking like the wiring on this page, you are doing it wrong!
Thank you so much for this advice - i am going to have a go this afternoon. I will update you to let you know how successful i am.
Again, many thanks you are a star!
The base plate of the EP3002 is also the junction box or wiring centre. Ideally you need to transfer this to a 10 way junction box, and introduce the Nest wiring into this.
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