As a CORGI registered installer, I have been podering upon the stated need for cross bonding between the pipes connected to a newly installed gas central heating boiler.
Assuming a typical UK domestic household, where the services are correctly connected to earth as close to the entry point of the dwelling. I install a new central heating boiler. With the make of boiler I install, the central heating flow / return, hot / cold water and gas pipe are connected to metal compression fittings that are in turn mechanically fastened to a metal bracket that forms part of the boiler's casing.
It seems to me that this metal to metal contact between all of the pipes is better and more robust than using earth bonds and a cable connecting them. It is possible that the earth cable or bonds could become slack, or due to the possibility of corrosion, become less effective. The metal bracket of the boiler is a solid piece of equipment and to me, provides a more than adequate cross bond between the connected pipes.
Comments?