I want to connect some electric to inside garage, I have had all the work done, Plastic yellow pipe about 4 inches round under floor in house and under garage base then under block paving outside garage at least 50cm deep. Can i use noraml 16MM twin and earth cable??? From inside/house consumer unit to garage consumer unit? No one will be digging block paving up. Or digging concrete garage base up. If not Why and waht are the dangers??? Thks.