UPS Has Voltage Present Between Neutral and Ground While On Battery
Issue
When a Uninterruptible Power Supply (UPS) is on battery power (i.e., when normal power is lost), voltage can be detected between the neutral and ground conductors of its output.
Explanation of Issue
UL requires backfeed protection on any UPS. The implementation of this backfeed protection results in measurable voltage between neutral and ground while the unit is on battery power. This is phantom voltage and cannot cause damage to equipment. See this article from Schneider Electric for more information.