Electrical Blast is objectively the worst of the blast sets.
1. Endurance drain is pointless. NPCs don't have costs to their powers. They have drain. The "cost" is deducted from their endurance. The only check which is made is if they have any endurance. So if they have 1 endurance, they can use a power that "costs" 100, at which point they'll have 100 removed from their total endurance, 99 of which was meaningless. So for endurance drain to be a meaningful mechanic, you have to get them to 0 endurance and keep them from recovering any. If you think that's what Short Circuit does, see the next point.
2. -100% Recovery doesn't zero out endurance recovery on NPCs. It halves it, just like 100% deductions on recharge, or endurance reduction. On this point, I'm not actually sure. It's just the most likely explanation given that you can demonstrably prove NPCs get endurance back while being chain Short Circuited. Eventually they get endurance.
3. Voltaic Sentinel is much worse than the high damage single target attacks other sets get. Just simple math on this one. It does 1/4 to 1/3 the damage of the heavy single target attacks. It also does this less often given practical levels of recharge, as its rate of fire never changes. And you don't even get to decide who it shoots.
4. Thunderous Blast has 25 second longer cooldown than other T9 nukes. It does the same damage as them, but takes longer. It also has a longer animation time.