MGH's EPSS testing policy is designed to provide the required operational tests, using actual emergency power system components and loads also as required by JCAHO, with tests occurring at times that will not adversely affect clinical activity and will allow for maximum B&G response to equipment and/or system failures that occur during the testing itself. The test times are also intended to allow sufficient clinical and clinical support to respond to problems uncovered by the testing. During the tests, the Hospital maintains all normal power systems to the to allow for an expedient restoration of power in the event of a generator malfunction. The testing procedure is specifically designed to uncover EPSS problems in a closely monitored and controlled environment such that if failures are to occur, they can be corrected in minimal time. This continual testing program minimizes the risk that the EPSS will not operate properly in the event of an unscheduled normal power outage.

In addition to the monthly EPSS testing, load measurements (24 hour load profiles) of each ATS are taken annually. These load profiles are then interpreted, entered into a database and aggregated by EDG to determine the projected 24-hour load profile for each generator set by the Engineering department.

During these tests, B&G staff is assigned monitor the
generator and ATS's to ensure both proper operation of equipment as well as to verify the test provides sufficient loading to EDG’s. In accordance with JCAHO, the MGH test procedures require a minimum of 30% be applied to each generator to avoid wet stacking of the EDG. Running loads are recorded every 10 minutes during the test, and the interpretation of these values requires that at least 4 consecutive readings (representing at least 30 minutes) be above the 30% load test requirement.
The minimum of four consecutive readings is considered to be the EDG test load for that test. The Engineering department reviews all testing records provided by B&G and maintains an archive of past tests for future reference.