How To Install A Power Cord On A Hardwire Battery Backup UPS
In this video, a NEMA L6-20P (plug, twist lock, 208 volt, 20 amp, single phase) power cord is installed on a 6KVA / 5.4KW hardwire Battery Backup Power UPS (uninterruptible power supply).
Typically, a NEMA L6-30P (plug, twist lock, 208 volt, 30 amp, single phase) power cord is installed to allow for the maximum output (5.4 KW).
In this case, the customer only had a NEMA L6-20R (receptacle) available and only needed 3,000 watts of uninterrupted power, so a NEMA L6-20P (plug) was installed.
Here's the math on this custom power cord: 208 volts X 20 amps X 0.9 UPS power factor = 3,744 watts available from the UPS output without switching to battery power alone. Typically a 30 amp power cord is installed as it allows for the maximum output: 208 volts X 30 amps X 0.9 UPS power factor = 5,616 Watts (maximum is 5,400 watts, so any number higher is acceptable).