Hello folks,
Rather than finding out myself, the hard way, by building them until they won’t work any more -
Is there a limit to the number of electromagnetic generators I can build on an electromagnetic hot spot? Is there a point at which they stop working because I have too many?
I have built 8 at one hotspot successfully so far.
You could just try in creative mode, that should make it a lot less hard.
ATM, I don’t have a free save slot. A couple of my saves are pre-NEXT, so I suppose they should go eventually - but for now, creative mode isn’t available. 
I believe there is a radius involved from the hot spot itself, but for as far as I know, this allows more than you will likely need. I do not think there is a limit to the amount besides construction limits of course.
Plus, you can stack them on top of each other…
Yeah if packed together and stacked nicely, you most likely reach build limit before you get outside of the resource radius. Diminishing returns over distance from source … including height.
I have 12 EMGs down on a C-class hotspot. I can’t remember the details right now but I do remember that by Using one that you have put down, it will tell you how much power V/m you can pull from the node, as well as how much each EMG can pull 150kP. From there you can judge at what point an extra EMG will provide no more power.
As well I agree with what others have said here: There is also a radius to the hotspot, but not sure how to determine that.
Hope this helps
From a Generator linked in a grid of 12:
The 12 EMGs (in a rainstorm)
