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multi-way cable & mains

Simon Hailes
Hi All,


Ref. wiring lights & a window opener in my conservatory;

This question mainly comes about because the window opener has three wires, neutral and two lives.  I've read a few posts about use of 'flex' for mains, but there is not much on use cable with 4 or more conductors.


I have:

An outside light (LED flood)

An inside light (5 mini-edison, currently LED)

A mains window opener ('up', 'down', 'common', 26W).


A 'control box' (set of relays connected to ESP8266 MCU, plus the 433mhz opener controller).

'switches' - a switch for each light, plus a biased switch for the opener.

The light switches will be in parallel with relays - so when switched off, the lights can be automated.

The opener switch will also be in parallel with 2 relays (and drives inputs to an opener controller).


The lights and opener could terminate up on an exposed beam near the light on the ceiling.  This would mean that I would only need 4 'live' wires plus neutral and GND (so 6 conductors minimum) between a junction box and the control box.

The cabling would be exposed (some may be in conduit).


For the switches, two would be switching live mains, and the biased switch would be switching two wires of undocumented 'control' (probably 12v dv) to a common ('signal gnd' of the opener controller?) (I will meter these and check exactly what voltages are involved).


The 'control box' will be powered from a plug, so the complete system can be isolated....


Questions:

1/ if connected to a plug, is this covered by part-p?


2/ I'd like to minimise the wiring to keep it pretty.  From the junction box to control box:

I could (for economy) go with a pair of 3-core+earth, or I could go with a 6 core multi-way cable.  Or I could go with 3 x 3 core cables, treating each device as separate.

But whatever I do, the colours of the cables will not completely represent their function - e.g. if using 3 core flex for the opener, then the earth would be used for neutral, and that seem very BAD to me.

So I like the idea of a multi-core better, if only because at least I may be able to make neutral blue and earth green, and the other colours NOT being standard will at least make someone in the future think twice...

When looking at available multi-core cable, (e.g. on CPC), most is quoted as 'control' even though rated good enough for what I need (1mm sq, 300v?), is this just because it's not std colours?

Comments and thoughts appreciated :).


3/ I'd like to minimise the wiring to keep it pretty (2).  From the control box to the switches:

Since the biased switch is assumed to be DC (and I probably can't get a biased switch which will fit in a 'normal' domestic switch arrangement), I'm thinking that it's wise to run separate wiring for the switching of live for the lights and the DC switching.  Am I right to think it's not good to run them in the same multi-core cable, or just paranoid?

I'd like to use black flex for the mains switches.  I assume 4 core would be ok - live + two switched live + earth?  Is colour important if all wires are sleeved red at the switch?


thanks in advance for any thoughts...


Simon
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    With ref to the oversleeving... I am of the (controversial) opinion that brown/black/grey are all phase colours, and do not need oversleeving.



    But by the letter of the regulations, black and grey don't just identify any old line (phase) conductor, but specifically line 2 and line 3 of a 3-phase system - which of course in this case they are not.


    That's not to say I don't have some sympathy for the idea - the French approach of regarding any colour other than blue or green/yellow as line in some ways makes life an awful lot easier (especially in conduit systems - popular in their domestics). Imagine wiring a switch where you could immediately tell from the core colours which were the permanent lives, which was the switch live, and which were the strappers, all without having to mark anything during drawing in, or bell out, or oversleeving. A much more "workman-like" approach IMO.


    I do leave black unsleeved as a smoke detector interconnect line - as that's a valid colour for control & signalling circuits by table 51.


      - Andy.
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  • 0

    With ref to the oversleeving... I am of the (controversial) opinion that brown/black/grey are all phase colours, and do not need oversleeving.



    But by the letter of the regulations, black and grey don't just identify any old line (phase) conductor, but specifically line 2 and line 3 of a 3-phase system - which of course in this case they are not.


    That's not to say I don't have some sympathy for the idea - the French approach of regarding any colour other than blue or green/yellow as line in some ways makes life an awful lot easier (especially in conduit systems - popular in their domestics). Imagine wiring a switch where you could immediately tell from the core colours which were the permanent lives, which was the switch live, and which were the strappers, all without having to mark anything during drawing in, or bell out, or oversleeving. A much more "workman-like" approach IMO.


    I do leave black unsleeved as a smoke detector interconnect line - as that's a valid colour for control & signalling circuits by table 51.


      - Andy.
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