Honeywell heating pack S Plan cable

[Mike2007]

Do I need 3/4 core cable for wiring a conventional S Plan heating system? Please advise.

3 core cable for room stat
4 core cable for programmer
4 core flex for valves
3 core flex for tank stat
3 core flex for boiler/pump

Can it all be done in 0.75mm cable or do I need 1.00mm?

Thanks

 

[Rob]

Most motor valves are 5 core.

And if your your pump has to be wired into the boiler then you'll need 5.

 

[Mike2007]

"Most motor valves are 5 core." Grey(perm live),orange(boiler live),blue(neutral),brown(sw live),earth. Is that right)

"And if your your pump has to be wired into the boiler then you'll need 5".(its a system boiler, will wire to panel and use jumpers for pump I think)

Is 0.75mm wire ok, but it might depend on boiler I guess.

 

[namsag]

.75 is the correct size to use anything that goes into the boiler must be heat resistant cable so just as easy to wire it all in heat resistant . .75 only costs about 18 quid for a reel of 3 core.
Motorised valve come with with flex already on it,

 

[simond]

Technically the size of cable is worked out using volt drop and earth loop requirements.

Practically, unless the boiler and controls are really far apart, 0.75mm is sufficient in most cases.

Colours used for phase conductors (eg: L&N) should have Brown or Blue sleeves or markers at the termination points. In other words, if you are using a black as the 'pump live' from the boiler, it should be marked with a brown identifier.