I have every respect for him that he is trying to learn off his own back, but the regs are there for a reason (Mainly Safety) and if he is learning how to do stuff then he should find out how to do it properly. Otherwise he will be just like those other idiots out there that saw a picture of a burglar alarm and now think they are an experienced installer. Mains should be segregated from low voltage cables, not just for safety but to stop ac noise getting onto the low voltage circuits. If you dont point these things out how is somebody supposed to learn.