Crit chance wrongly computed on lightning conduit

I'm doing a crit lightning build, and arc has 32.04% crit chance, but lightning conduit has 21.2% crit chance, how come? is crit chance computed differently if the spell is an aoe? (arc has a base crit of 9%, and lightning conduit of 10%).

I had it at around 20%, took a 10% crit spell chance on the passive tree, it should have been increased to more than 22 %.