There might also be a followup examination with a thermal camera of the property, which with a server farm, would also show significantly elevated temperatures.

This is why most of us in the USA live in constant fear that our hobbies of basement aluminum smelting operations will land us on the wrong side of the law enforcement.

judges here will sign warrants for anything. the way their positions are doled out a key qualification to being a judge who signs warrants is intrinsically trusting cops

Not even a power bill. They have been known to sign warrants for nothing more than an off the shelf infrared scanner/heat scanner showing increased heat from a specific unit in a building compared to the surrounding ones.

Like your house nice and toasty in the winter? That's a no-knock-raid.

I've had cops come around to check out what they could when I was living with roommates and we had all kinds of equipment that used lots of electricity. We actually got a letter from the power company telling us we were in the 99th percentile of residential power use and to consider how much money we could save if we lowered our electricity useage. I'm sure if the cops saw anything they could construe as evidence when they were snooping around they would then easily get a warrant and do a raid.

I wonder how high it needs to be to get to that point.