cable run and water pipes

[serge33]

need to channel in some 8mm central heating pipes, and they are just where i want to fit a new lightswitch, can i run the cable down the same channel or do they need to be kept a set distance apart??

 

[pompeygit]

Regs 528.3 and 528.3.4 supply information on this scenario. Remember that plaster acts as a heatsink for electrical cables so placing heating pipes in the vicininty will not allow effective heat dissipation of the cables. Effectively you are de-rating the cables if the pipes are too close. If the heating pipes are in close proximity to the cables they become exposed extraneous parts(sounds b******s to me) and need supplementary bonding. No mention is made of a safe distance between the services so I guess common sense is the main factor. Personally I would have thought 3-4" from the edge of the pipe to the cable would be ok in the plaster, but maybe 6" in the void above, what is the take on this from the rest of you guys?