Welcome to the forum. Although you can post in any forum, the USA forum is here in case of local regs or laws
I would still stick to the 25mm ruleFrom a scan of 17th Edition Amdt 3 Wiring Regulations, there is no minimum clearance from a cold water pipe (regulation 528.3). For gas pipework the minimum clearances are 25mm from a cable to the pipe and 150mm from an electrical switch to the pipe.
For hot water or heating pipework the regulations state: -
'A wiring system shall not be installed in the vicinity of services which produce heat, smoke or fumes likely to be detrimental to the wiring, unless it is protected from harmful effects by shielding arranged so as not to affect the dissipation of heat from the wiring.' - Reg 528.3.1
Reply to the thread, titled "Plastic cold water pipe distance from mains electrical cable" which is posted in Bathroom Advice on Plumbers Forums.
We recommend City Plumbing Supplies, BES, and Plumbing Superstore for all plumbing supplies.