Mackwell asr664 is an autotest emergency inverter for use with t8 lamps with wattages between 18 and 36w it is fitted with a 5 pole relays to swich all four lamp connections from ballast to inverter and 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 and provide complete isolation to the control gear this inverter should be used with a 3 cell battery pack