On May 24, 9:43*am, "BruceB" wrote:
"js.b1" wrote in message
...
Note cables should not run loose on ceilings because of the 50mm from
finished surface rule.

Which rule says 50mm from surface applies to ceilings?
522.6.6 relates to walls.

522.6.5 relates to ceilings & floors (p59 of the 17th OSG).
Where a cable is installed under a floor or above a ceiling it shall
be run in such a position that it is not liable to be damaged by
contact with the floor or ceiling or the fixings thereof.

So the rule does not apply to cables run loose on ceilings.

However, consider a cable penetrating a joist and then running
parallel to the joist along the ceiling - it is quite possible someone
may screw into the joist using a stud detector and by chance catching
the cable. An example would be a battery powered CO alarm or smoke
alarm to the ceiling, or clothes airer, CO or smoke alarm, wireless
camera or office style lowered on steel cables (can be great for
hiding cable trays of networking cables :-)