why does reg. 543.2.3 prohibit the use of a gas pipe as a protective conductor? After all it can be main bonded and then carry substantial currents under certain conditions.
Current of itself does not cause an ignition risk. The ignition risks are heat (auto-ignition of the gas at a high temperature - for methane this is around 480-490 degrees Celsius) or sparks causing ignition (as used to light a gas hob). As mapj1 says the risks (of explosion) while the pipe is closed is probably nil as there is no gas outside the pipe which is therefore not an explosive atmosphere, and only pure gas inside the pipe and therefore also not an explosive atmosphere. However there are other dangers he points out which need to be considered.
Current of itself does not cause an ignition risk. The ignition risks are heat (auto-ignition of the gas at a high temperature - for methane this is around 480-490 degrees Celsius) or sparks causing ignition (as used to light a gas hob). As mapj1 says the risks (of explosion) while the pipe is closed is probably nil as there is no gas outside the pipe which is therefore not an explosive atmosphere, and only pure gas inside the pipe and therefore also not an explosive atmosphere. However there are other dangers he points out which need to be considered.
