I am going to answer this from memory and let special location shoot me down later if I am wrong. :x to special.
I have always tried to keep all electrical cables away from the main gas supply by a distance of 150mm.
For all other pipes, heating I keep at least 50mm away.
I do the same for all other services, water, extra low voltage etc.
I have also used barriers where it would be impossible to acheive a 50mm distance, by the use of insulation and or reflective aluminium sheets.
Again, this is only from memory and what I normally do, so my answer is not intended to inform you of the regulations, I cant read the brb as well as special location:^O