There is alot of possibilities on this on. Most likely it is in your input or output. You may have a 208V or a 480V input but your UPS may be programed for 240 or another voltage. I have the manual and all the knowledge you need. Email me at [email protected]
It either means the ground wire in extension cord is not there or is open. It could also mean that the outlet wasn't wired with a ground back to the panel.
