Hi,
Just making a little note about the number of elements you would need. If you were to buy elements designed for 240v, you would need a rated 3,000W x (240V / 60V) ^ 2 = 48,000W and on top of that, you might have to account for the relatively high positive temperature coefficient.
And it would get worse if you try to dissipate the same power at lower voltage.
Note that if you can buy overseas and find elements designed for 120V, you'd only need 3,000W x (120V / 60V) ^ 2 = 12,000W
Edit:
I got a couple more ideas, some might be too expensive or too much out of the box.
- use a dc to dc converter to step up to the elements rated voltage. Or down to a more standard voltage.
- charge a battery bank with the 3000W and reuse the power later for something useful/fun.
- use a mechanical load. For example, a restricted pump. If you use a variable reduction, you end up with a very flexible load.
- a big electrolysis tank if good ventilation is available. You can easily vary the load by varying the immersion of the electrodes.