KnowUPS - Getting More from your UPS: Issue I - EPO

EPO or Emergency Power Off is a safety mechanism intended to power down electrical equipment in an emergency, in order to protect personnel and facilities.

Most modern UPSes feature an EPO terminal block.  However, no one has ever asked me about it and I rarely include the EPO block in the sale.   On the APC SUA SmartUPS line (200B) they are located by the comm ports.  It is a simple Normally Open contact block

But EPO does has a place and its actually required above 750va according to NEC code.

"A means shall be provided to disconnect power to all electronic equipment. The disconnecting means shall also disconnect the battery from the load."

Since UPS units are always providing electricity, whether the power is on or off, having a way to kill all electricity quickly does have a purpose.  

Realistically, as electricians, we rarely see anyone actually connecting small UPS units to a EPO switch.  But as we have seen in our lab, DC voltage from batteries can burn and hurt.   Read more from APC's whitepaper.

Bottomline, if you need or want the EPO feature, be sure to ask for the contact block to ship with your order.