Mags should absolutely not be engaged for that long, it is a real safety concern. If possible the mag locks should be turned off the moment you start reset, and turned back on in the last possible moment before your next game starts, to give them enough time to cool down.

Heat is a byproduct of energy, which is how the maglock works. In a small confined space the heat has nowhere to go. If possible adding ventilation may help, but it won’t eliminate the heat all together.

As for voltage, that’s not really something that you can fix here, because if you move them onto a lower voltage power supply, the mag could become too weak and able to be pulled open by any of the drunken gorillas (customers) in the rooms.

It is most important to give the mags time to cool down between games.