I have just seen the jpeg of the garage distribution box. The description I wrote assumed that you had shown the distribution box in the house. Is the supply to the garage run from the distribution box in the house? If so what size circuit breaker does it connect to? If not how is it connected...
I would like to help with this but I can't open your jpeg. No one has mentioned anything about cable sizes which is just as important as the MCB rating. Have you determined which of the two MCBs already mentioned actually supply the garage. Try tripping them to find out.
Once you done that check...
Thank you for the welcome message. I am a woodworking novice but want to learn more. As yet I have no projects on the go. I am planning to make a sled for my table saw. There are so many options on You tube, I am leaning towards the microjig 360 sled.
Best wishes to all.
Jeff