I have a 2200 model UPS which has the following error:
Critical Events - UPS: A site wiring fault exists.
Our electricians have checked the outlet and stated that it is functioning properly.
Does anyone have any idea why the UPS would still have this error?
What did your electrician check specifically? This can come up for the reasons defined in the knowledge base (http://www.apc.com/site/support/index.cfm/faq/) and refer to article ID FA158817.
They checked the voltage, polarity and ground.
Are you able to try it in a different receptacle circuit to see if it goes away? If its a 120V unit, maybe the neutral is overloaded too?