I am having a built in box fitted to an outside wall prior to my utility connection company moving my gas meter and my Corgi plumber completing the back piping. The wall / cavity has cistern overflow pipe and a sink waste pipe through it. Are there any regulations about the proximity of the gas pipes into and out of the meter box that will dictate where we place the meter box.
There are no regs that will prevent you placing it regarding any overflows or waste pipe!! There are regs when it comes to incoming electricity mains or if it is a Medium Pressure Gas service to your house, however. Hope this helps.