Disclaimer: I am not an electrical engineer; nor do I play one on TV.
Well, FWIW there is this:
https://www.powerstream.com/Wire_Size.htm
At 56v, 1000 watts is about 17.9... lets call it 18 amps.
18ga wire, according to that chart, should be good up to about 16 amps in free air; but only 2.3 amps in a bundle... this leads me to thinking that the wire in question is a bit on the light side for the task at hand. On the other hand; I often see transformers wound with lighter gauge wire than what is feeding them, so... ???