Wiring in an MVHR unit

17 Sep 2004
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United Kingdom
I'm wiring in an MVHR unit. I'm doing a lot of wiring on a house build myself, to be signed off later.
So, I have this wiring diagram:


My query is, apart from the L/N/E in, the rest is from the controller to the unit.
So there are a number of wires running between them.
Presumably, there's no need for heavy wires, but I'm trying to work out a tidy way of doing the wiring. There's no information on what weight of wires to use, so I'm thinking somewhere between a six wire alarm wire and two 3 core + earth wires, but the latter is really NOT neat.

Any thoughts, please?
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Well, if that schematic is true, then the wiring carries the full power of the motors. So it must be mains rated cable, alarm cable will NOT do! It must also be of adequate size for the load, and of adequate size to be protected by the fuse feeding that unit. Where is your power coming from? 3A FCU?

Something like this (known as type YY control cable) may be suitable, as long as it meets the above requirements... https://www.tlc-direct.co.uk/Main_Index/Cable_Index/Flex_7_Core_Grey/index.html
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Yes, a 3amp FCU for power.
I've never seen YY control, before.
The one you mention looks OK.
This is the power requirement, (in red).


What wire size would I need?
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