@frontrange said in Is there any reason not to use an AC powered heat bed?:
Since I've never done anything but low voltage DC heaters I'm just checking to see if there is any reason (other than aversion to mains) that I would not want to do that?
The only reason not to do it is if you don't have enough knowledge and experience to do it safely. Things to consider:
The metal parts of the printer (including those on the bed) must be grounded, for safety
The terminals carrying AC mains power must be safely kept away from prying fingers
The wires must be sufficiently insulated and prevented from chafing. This is easy if the bed is fixed (e.g. in a delta printer), more difficult if it is moving. A moving bed requires strain relief at both ends of the cable to prevent it breaking where it enters the terminal.
Additionally, you should consider what will happen if the bed heater gets stuck on at full power. With an AC mains bed it is easy to use a high powered heater that will raise the bed temperature to a dangerous value. So you should either choose the bed heater power carefully so that the temperature rise will be limited to a reasonably safe value at full power, or use a thermal cutout mounted on the bed or bed heater.
For a 300mm x300 mm bed I would definitely use an AC mains bed heater.
