New build garage electrical

Your not certifying the works, they are. What reason would you not trust what your told, are they registered?. The minute you told me you was looking into BS7671 and wasn’t an electrician I as an electrician would walk Away. What reason did you have to look into What you was told. This isn’t a question of wrong or right just trust. Technically there’s not enough information to answer your question. Some major variables that are important to your question are missing which show a lack in your knowledge. Please don’t be offended I’m sure you mean well.

Not great is it? Why not a dedicated circuit back to the consumer unit. It’s Mickey Mouse stuff, like a diy installation. When I saw ‘new build’ I saw the red lights flashing. Impossible to tell if this is even compliant or not, remotely anyway. I would certainly get a 2nd opinion, independant of the electricians.

If the ring main has been taken into the garage, then the light spurred off the garage socket via a fused spur (fused down to 3a) then this is fine as the spur is the light. If a 4mm radial cable has been used to spur from the ring main inside the house to the garage double socket, this is also fine, as long as the lighting cables in the garage are fused down (you can’t fit a 4mm cable in a light fitting usually) If the spur is a single 2.5mm cable (twin and earth) and it’s feeding both a double socket and a light fitting, then no this is not correct as the double socket can draw 26a and the light potentially 1-3a. A single 2.5mm cable can handle a load of 26 amps depending on how it’s installed. The quick fix to your problem if the spur cable is a single 2.5mm twin and earth cable, is to change the double socket in the garage to a single socket. Then make sure a fused spur is installed to protect the lighting in the garage. It gets complicated if different types of cables have been used to spur from the house. Our job as electricians is to ensure it is impossible for you to pull more power through a cable which it can not handle. Different cables have different ratings, meaning your installation could be ok, but without looking at it, it’s difficult to determine. If it is a 2.5mm twin and earth spur into a double socket and a light fitting which has been hard wired, the simple fix to this is put the light on a plug top then plug it into the double socket. You can’t pull more than 26 amps that was as one of the socket outlets will be taken up by the lighting plug top. Alfie

I don't understand why people question things like this. Why do you? Its perfectly acceptable to spur one socket, single or double, off a ring. Your electricians are correct. And your description implies the light is also wired off this socket. It isn't, is it!