Sounds like nonsense to me (when considering length of hook up) - surely the resistance of the earth conductor is similar to that of the live and neutral conductor - i.e. same length and same material. And able to carry a lot more than 30mA.
I'm not sure what you are saying is nonsense,I never stated that the resistance of the earth wire may be too high to carry enough current to make the RCD trip or that the cable might not be able to carry enough current to trip the RCD a previous poster stated ,Quote
"If the earth wire is long, and thus higher resistance, then the current leakage will be less and the RCD may not trip or may be slower to trip."
The statement in bold in the quotation marks is the bit that is nonsense but I refrained from pointing it as such.
.I was pointing out that if the resistance were high enough ,perhaps due to a corroded connection then the RCD would't trip anyway not that the earth wire if uncompromised would be incapable of carrying enough current.
It was suggested that if the earth wire was too long then the resistance would be higher current leakage will be less and the RCD may not trip or may be slower to trip.,(not my words) for it to be too high the the difference would need to be in Kilometers not metres probably in the region of 8000 ohms
.If the earth wire is intact then the resistance of the earth wire in a 30m hookup wuld be insignificant,even if due to a high resistance joint in the plug of 10 Ohms it would still carry 23 Amps.
I can't understand why you referred to what I had written as nonsense but ignored the obvious post that was incorrect!