hi mate,
im gonna presume its a combi boiler so...
fistly is the room stat fitted if so have a look at what wires go where in that to make sure you can connect to the right ones at the spur.
On the 5 core connect brown and blue to load side of spur (obviously) (make sure 3 amp fuse in there as well)
next you need to gain access to the boiler electrical connection, prob coupla screws at the bottom front edge and cover might lift up and away? then there will probably be a white panel that will pivot towards you if you remove 2 screw again.
im kinda guessing on the above bit as i cant picture the exact model etc, but if the above is succesful then you sshould have a white panel pivotted and laying flat in front of you, unscrew the back of this panel to gain access to the wiring.
take the 5 core and insert it thru one of the spare cable clamp entry points and secure the 5 core once you have enough inside the casing.
strip your 5 core connect brown and blue to the boilers L and N connections, connect the earth to earth.,
then there will possibly be a red link cable going from one terminal to another one, this is where you connect your remaining 2 wires of your 5 core, they may be labelled S! or S2 or something else. which ever labelling looks like its the common connection i.e s1. then whichever wire was common for the room stat (determined earlier) then stick that in this connection and the other wire in the other one.
i always put a bit of brown sleeving on theses 2 wires as well. then which ever wires of the 5 core you have used for the room stat connection in the boiler, connect them to the room stat wires where the sw/spur is, just ues a connecty block and put a bit of tape round it, and also some brown sleeving
then hopefully that should be it, if the boiler is purged with gas and ready to be switched on then flick the spur on and keep your fingers crossed youve wired it right and not blown a pcb!
no its long winded all this and not sure how much of this you need to know, just hope it helps!!
rich
then which ever wire was the "common" wire at the room stat
as gazhudds said, however a lot plumbers will fit these as there a push fit connection you will soon see 2moro