Hi, I am in a debate with a friend who is also an electrician who is backed by his boss in this. Now I am aware of all the electrical zones like - 150mm from a ceiling and 150mm from the corner of 2 adjoining walls or partitions and horizontal or vertical from any accessory or switch gear. But the thing I don't agree with and can't seem to find any information about is that from a metal back box in a wall there is a 50mm zone all the round it? Ie. If you had two boxes in line with each other you could run the cable round the edge of the 2nd box to pass it rather than go behind it. Is this true? Thanks.