Broan C907 30 VA 16 Volt Transformer Not all transformers are equal and this one is the most powerful transformer we offer. NuTone transformers feature an easy to install lock mount or wall mount that can reduce installation time by 25%. An additional unique feature is the thermal cut off switch designed to shut off the door chime system in the event of excessive temperature. NuTone saves you time and money. 16 volt, 30VA transformer for powering multiple door chimes in one home order in standard package of six to help assist with your planning and still retain that economical edge. Quick install transformers, built to last so you should have fewer call backs. One 16 volt, 30VA transformer powerful enough for up to three chimes saving you installation time.