Mackwell ASR664 is an autotest emergency inverter for use with T8 lamps with wattages between 18 & 36w. It is fitted with a 5 pole relays to swich all four lamp connections from ballast to inverter & switch of the power to the ballast during emergency lighting testing. The modules can therefore be safely connected to a circuting with an electronic HF ballast & provide complete isolation to the control gear. This inverter should be used with a 3 cell battery pack.