Using green/yellow as switched live

The neutral connection on the boiler for the pump is there for convenience. A neutral may be taken from the wiring centre if you wish to do so.

Adam

Screwfix was a possibility...but the fact that I couldn't get it very locally perhaps explains why the job is often bodged..

Most likely neutral, live, switched live (and we'll forget about earth).

-- JJ

On 24 Jan 2009 15:01:24 GMT someone who may be "Bob Eager" wrote this:-

has six cores plus protective conductor. That should be fine for most household systems. Unused cores can be terminated and left spare.

Think I looked at that one, but nothing about being rated to 90 deg. C.

On 25 Jan 2009 11:45:43 GMT someone who may be "Bob Eager" wrote this:-

Simply terminate it near anything that may get hot and use suitable cable from there to the hot bit.

I don't suppose that cowboys who use the protective conductor as a live one bother about temperature ratings either, but there isn't a rash of melted flex. Certainly none of the boilers or pumps which I have used have ever been so hot where the supply wiring runs that normal PVC covered cable would be in any danger of melting.

The thing was only a metre long. And I'd still need to source the cable for the last bit. The spec said 90 deg. so that's what I used.

So you'd ignore the recommendation in the boiler installation manual?

Don't think much needs high temperature cable - except perhaps an immersion heater connection. The current everything else takes is low, and PVC won't melt at the sort of ambient temps you'll find on boiler connections.

As I said, I was just doing it 'by the book'! The new boiler is a lot cooler than the old one was in the same places, but that's what the book says!

(and, after all, one of the reasons *I* did the electrics was to avoid having any bodges (well, bodges that weren't mine!) done)

On 25 Jan 2009 12:18:57 GMT someone who may be "Bob Eager" wrote this:-

Then I wouldn't bother to use it.

Did I say that I would?

While six cores plus cpc is suitable for Y plans - I've used it myself, unfortunately you need seven plus cpc for S plans. I'm not aware of any supplier of this.

Nothing wrong with using multiple flexes - provided the earth wires remain just that.

I wire up S plans quite often and I have never needed 6 cores plus CPC.

Do not leave me guessing, why did you need more than 6 cores?

Adam

Best practice is to sleeve the spare cores with green/yellow and terminate them to earth.

Adam

I've done that with thermostat and programmer runs but the 6 core flex with multiple colours simplifies installation and fault finding immensely if you have a 10 or 12 way chock block/wiring centre close to the boiler and another one in the airing cupboard/next to the diverter valve and run the 6 core between the two and then 3 core flex to the diverter/hot water thermostat/boiler/fused spur. No mixing up of browns and blues and every core colour ties in with the standard Y plan scheme. Thing is (and as someone who looked at it a few months ago said) with all the cables neatly clipped it just looks too neat for any spark associated with a CORGI to have installed it. :)

I dread looking at the CH wiring in my parents place. Wired by an idiot who looped the boiler and pump T&E round the boiler and OH stat capillaries! There is no colour coding whatsoever, no wiring diagram either until I buzzed it all out - and despite it claiming to be a Y plan there was an unconnected core that would enable the heating to run independent of the hot water.

From the standard Honeywell diagram

Really s***ty copy here

Terminal 1 Grey wire to both zone valves (common contact) Terminal 2 Blue wire to both zone valve motors Terminal 3 Green Yellow cpc to both zone valves Terminal 5 Brown to heating zone valve motor Terminal 6 Unspecified colour to cyl stat normally open Terminal 8 Brown to cyl stat common and hot water zone valve motor Terminal 10 Orange wire to both zone valves (Normally open contact)

I can't see any further scope for core sharing and so make that 6 cores plus cpc. (not the seven plus cpc I said)

Maybe it was 5 plus cpc for Y plan and 6 plus cpc for S plan and it was the 6 plus cpc I couldn't find This would be around 8 or 9 years ago I went round all the local electrical factors plus Newey and Eyre and CEF.

I would have preferred to go S Plan because I had previously acquired a large box of unused 2 port 22mm valves at an auction and the desire to use a single cable rather than a hotch potch of T&E on a brand new build mean that none of them got used and I had to go out and buy half a dozen 3 port valves (it was a multiple holiday let installation)

Depends on how through you are being on the programmer to wiring center connection. I can see 9 wires being used:

Supply (L N E) CH (NO C NC) HW (NO C NC)

One wouldn't normally need the two NO's in S Plan and the two C's could share the L but you loose flexabilty at a later date by not having everything back in the wiring center.

Interesting. I also have to fault find Y and S plans frequently so a setup like yours would be nice to fault find on. I usually see T&E everywhere with bits of flex etc

I keep 3, 4, 5 and 6 core flex on the van but the 6 core lasts for ages.

I have never wired a system up in this way but it seems a reasonable and logical way of doing things.

Cheers

Adam

Uh! I wire up all sorts of controls and have never needed more than 5+E.