Can someone tell me exactly what the wiring regulations say in practice about running cables through joists?

I have re read the 16th. ed. on site guide but it is as clear as mud to an amateur!

There is a point upstairs where I have bunched the cables which run under the landing to avoid drilling extra holes and avoid weakening the joists.  All cables run 2" down as they should. Everywhere else they are separated  by at least a cables width except when running under capping to switches/sockets.

However, I am now told that not only is it not good practice, although it was common to do this in years gone by, but these days will lead to incorrect readings, and that I should have bunched only the lighting cables, if any.

As ever,all advice welcome......


Thanks

JohnD

Bear in mind however that mains and other cables should be separated by at least 50mm.

So if there is a telephone or aerial cable in the bunch then it ought to be separated.

HM