the ciopy of the tabvle i have says that : "this table is a guide only, and is for disconnection times upto and including 5 secs. For other times consult the cable manufacturer"I'm sorry johnboy but I don't get it, it states a copper equivalent Cu, if this isn't meant to be the size of a copper conductor having the same conductance as the swa, then whats the point .
From that chart how would I determine if the swa armour was equivalent or better than a 10mm copper conductor , for the sake of complying with TNCS minimum main bond size ?
SWA will be able to dissipate heat from fault currents easily because it has more surface area, as the armour is not bunched together.
In the case of the worst type of electrical fault, a long duration, low magnitude fault (like the TNC-s scenario as lenny mentioned), this dissipation will mean that heat is transferred into the inner cores of the cable.
So in other words, the k values which are used to calculate the copper equivelants, and are used in the adiabatic equation are only suitable for short duration faults.