Emergency Power Off (EPO) switches, also referred to as “Generator Remote Shutdown Switches,” are a hot topic of conversation. In the past two years (2018-2019), MGI has received multiple comments regarding proper placement and testing of the EPOs. Most recent discussions revolve around exercising/testing an EPO while the generator is under load.

Note: An EPO’s function is to immediately shut down the EPS if for whatever reason its continuing operation could pose a safety hazard or cause property damage.

NFPA 110, 8.4.1 states: EPSSs, including all appurtenant components, shall be inspected weekly and exercised under load at least monthly.

Paragraph 8.4.1 does not state the EPOs should be tested while an EPS is running under load. Operating the (EPO) under load for testing is OUT OF THE QUESTION!!!

“Shutting down an engine with a hot turbo can destroy the oil seals in a cartridge…and may lead to oil feeding directly into the air intake…resulting in a CATASTROPHIC OVERSPEED. NEVER test it while the genset is under load.” – Steve Works, Blanchard Machinery

Shutting down a loaded generator could turn into a 7-figure replacement and rehab project, plus leaving you in a tenuous situation if the generator is the only source of emergency power.