Site Wiring Fault keeps showing up in the APC event log

[stanj_apc]

We have an APC UPS connected to a server and the UPS is being monitored by PCNS software.

We continually see messages in the log file …Site Wiring Fault.

It occurs at different times for different durations but is constant.

We also see the UPS kick onto the batteries for a few seconds than back to standard power.

This has been going on since the unit was installed earlier this year.

I marked down a few days’ worth of the time the events occurred last week.

An electrician connected a FLUKE meter to the power strip that connects to the UPS from the wall unit to record if there are any spikes. 

He produced a report for last week and it does not show any abnormal power readings as compared to what PCNS is reporting.

Is there a specific setting or settings the FLUKE meter should be set to so that the issue can traced to why the APC keeps reporting the site wiring fault error and jumps to batter every so often?  

thanks