The earth connection needs to not fail before the wiring would . However, I suggest that it may be that the earth is via steel conduit or trunking, which is not able to fail in the sense that a cable would where the insulation burns off - there is nothing to burn, and by the time the steel melts the copper wires are long gone..

However, if the PE is the same sort of cable or wire as the main circuit, it would be hard to find a reason why it does not need to enjoy the same level of protection  I don't want to say never, but generally yes.

Mike.

My point is that normally PE is not essential for load operation continuity, additionally, most of the time I don't want a life safety load to be disconnected during fire due to an earth leakage or small earth fault. TO the contrary, we usually aim that it works as long as possible as long as there is no short circuit.

My point is that normally PE is not essential for load operation continuity, additionally, most of the time I don't want a life safety load to be disconnected during fire due to an earth leakage or small earth fault. TO the contrary, we usually aim that it works as long as possible as long as there is no short circuit.

normally PE is not essential for load operation continuity, additionally, most of the time I don't want a life safety load to be disconnected during fire due to an earth leakage or small earth fault.

On the other hand with lots of water and carbon particles about during a fire, earth leakage is likely to be high as you say, but that might mean that exposed-conducive-parts of safety equipment - and anything connected to them (e.g. pipework) - could we attain a hazardous voltage if the c.p.c.s are broken. Probably not very considerate to the firefighters and anyone else who happens to be inside the building still. Continuity of supply is usually handled by ensuing the protective devices are sufficiently obstinate - e.g. generously rated HBC fuses and no RCDs.

   - Andy.