Re: earthing cable thro comn ladder
The answer is maybe.
If this "earthing system" is really part of an equipment bonding conductor, then it has to be run with the power conductors.
If it is some supplementary grounding system that probably serves no good purpose anyway, than its probably Ok to do this.
The way this was phrased makes me think you might be in a country other than the US. If so, electrical regulations where you are may be different.