although my box has a space for fuse (3a) there is no fuse fitted, but there is a desperate fuse switch next to timer....
Maplin here I come.....
Not sure if we are talking about the same relay junction box, mine is actually a Satchwell Sunvic 437-2-802, not a Satchwell 432-2-802... is this a typo on your side?
My relay junction box would not work without the fuse (the PCB states that a 5A fuse needs to be fitted) as it would break the line.
Regarding the "desperate fuse switch" next to timer, I am not sure what you are referring to, may be a photo would help. There is a picture of my Satchwell Sunvic 437-2-802 on page 1 of this thread, it simply contains a PCB, a 5A fuse and a relay.