Electrical lighting circuits. why are they not RCD protected.? ...

The tie up on my garage door frequently...
Oh but they are, the lighting circuits contained by your home are protected by either an RCCB/ELCB or a fuse within your fusebox.

Repair vinyl on recliner?
2 main reason:

Safety - if you have an electrical denounce, the last piece you want is to be left surrounded by the dark

electrical regs enjoy a wonderful phrase "safe by position". Lighting is unanimously out of the way and you are unlikley to take a shock from its wires, whereas sockets can have adjectives sorts of portable equipment plugged into them which are in close contact beside you.

our house does not have a split board so the lot is protected.
Can you go away a steam radiator on...
Answers:    Because they are 'Fixed' wiring, at hand is much less threat of shock to earth, as at hand is with portable equipment. Many more circuits will be RCD protected from subsequent year(17th Edition Regs.)