bathroom light fitting

[broady53]

fitted new bathroom light they are 2 red a brown a blue 1 yellow/green and 1 yellow i have wired up the 2 reds together the brown n blue together the yellow/green i have earthed where does the yellow wire go

[heathfield]

Sounds like someone installed three-core plus earth cable. This is normally used for two-way switching, (like where you have a switch at each end of a hallway). If so, the colour connections will depend on the idiosyncracy of whoever wired it in the first place.
Get a friendly electrician to sort it out.

[tezestwing]

where are all these wires junction box?? ceiling rose?? pull switch?? the Blue is most probably the neutral WHATEVER YOU DO DONT MESS WITH LIVE TO NEG very dangerous you may need the fire brigade.
As heathfield says get sparky in HTH Tez

[tezestwing]

have you got a fan in there ? the yellow maybe belongs to it for the run on timer HTH Tez