Honeywell ST6400 Wirng

[hotrads]

Hi,
Needed to retile kitchen and took controller off wall, thought I had drawn correctly existing wiring but now heating works when hot water selected and "wiring centre/junction box" mini internal fuse blows if I select heating. To get hot water I have to switch room-stat to mid-way and vice versa to switch off

I have 2 cables first of which has grey, brown,black,blue and earth.
Second cable has brown,blue and earth.

Of the seven connections on 6400 (inc earth) what should go where please?

 

[seco services]

N
L
1 - HW OFF
2 - EMPTY
3 - HW ON
4 - CH ON

 

[hotrads]

Really appreciate you responding so promptly Seco but which coloured cable goes where ? i.e. does the grey cable go in terminal 4 etc. Sorry this has turned into such a nightmare

 

[seco services]

looks like 3,4 are round wrong way.

 

[simond]

3 and4 reversed would not cause the fuse to blow, so this is not the solution.

The OP needs to realise that the colour codings means nothing, each installer uses his/her own system.

Under the wiring regs all non brown cores used as phase conductors should be sleeved or otherwise marked brown. This is rarely followed amongst heating installers.

I could hazard a guess but this is dangerous; you could inadvertently hurt someone or yourself. The number of possibilities is quite high and mains wiring cannot be connected on a chance basis.

What I can say is that you are probably coneecting a neutral to 1,3 or 4........which will cause the fuse to blow.

 

[seco services]

never said it was
only one of

so why is the heating working with hw on ?
and hw working with heating on ?

 

[bengasman]

Under the wiring regs all non brown cores used as phase conductors should be sleeved or otherwise marked brown. This is rarely followed amongst heating installers.

This rarely done by anybody.

The only safe way to solve the problem is to completely chart the existing wiring system i.e. boiler, wiring centre, timer, stats, valves, and pump.
Once all wires are identified, sleeve and mark correctly.
After that, connecting all correctly will be child's play.

Treat all wires as if they are live, you can not rely on the colours as very often the wrong cables are used resulting in any colour being used for phase.

 

[hotrads]

Seco, you are the man !! thanks v. much, sorted.

 

[seco services]

what was it ?
what did you do ?

 

[BingoBongo]

what was it ?
what did you do ?

does it matter
your the man

 

[hotrads]

what was it ?
what did you do ?

does it matter
your the man

Seco, It was your N,L 1,2,3,4 advice and your query about the Grey cable, checked my sketch and realised you were right. Thanks again

 

[seco services]

couldn't work out how you had so many wires in their in the first place.