HtgEngineer is 100% right. If you don't want to listen to him OK go ahead - on your head be it.
Elsewhere there is a qualified industrial electrician arguing that because he's qualified to spec and fit 3 phase heavy electrics then he can do a 20A radial off a domestic CU for his mate. He can't 'cos he's not a registered DI and he'll be breaking the law if he does.
Having said that I agree with you 100% that there are some peeps out there who have all the pieces of paper under the sun but their actual work frequently needs rectification.
Such is life in red tape Britain!!
Cheers




