[en] The supplemental report covers seismic testing of the Engineered Safeguards Test Cabinet, over the range of 1 Hz to 35 Hz. To demonstrate the ability of the equipment to perform under such earthquake disturbances, the test specimen was subjected to vibration tests which simulated the seismic conditions for the PG and E plants. During testing, the equipment was operated and the critical functions monitored to verify proper performance. The results show that there were no electrical irregularities that would leave the plant in an unsafe condition. Tests were conducted on the Engineered Safeguards Test Cabinet in November of 1972, at the Acton Environmental Testing Corp., Acton, Massachusetts