The joists in my loft are less than 100mm in height, meaning that it is
impossible to drill a hole that is 50mm from both the top /and/ bottom
of the joist. I've found other posts that say to run the cable over
the top of the joist and have a baton either side and place steel
strips over the top, e.g.
http://groups.google.co.uk/group/uk....6345a2c9687a7d

In parts the cable/joists will have boards over the top. Can the cable
be run without earthed trunking/conduit? and does this comply with the
building regs? I can't find anything which explicity covers this in
the On Site Guide or the BS7671 Blue Book.