Electrical – Bathroom fan fluctuates in power when using countdown timer switch


I just installed this new fan in the bathroom: Utilitech Ventilation Fan 1.5-Sone 100-CFM White Bathroom Fan

However, if I use regular toggle switch, it works fine. But if I use countdown timer switch, Lutron Maestro Digital Countdown Lighting Timer specifically, it fluctuates in power like ON and OFF constantly.

I read the reviews of the fan product and someone mentioned the switch is not compatible since the fan is low wattage. I am not sure if I understand correctly. This exact same timer switch works with another fan model but not Utilitech.

Is there any specific configurations of the timer switch I should look for when buying one for the fan?

Best Answer

Take it back and get a different timer

The stock Lutron MA-T51 does not need neutral; however, it accomplishes this by trickling power through the load. This is fine for large loads, but for low loads, (less than 40W or 0.3A), it causes the repeated on/off cycling behavior you are observing. (This is mentioned in the troubleshooting section of Lutron's installation guide for the MA-T51, even.)

So, you'll need to take it back and exchange it for a Lutron MA-T51MN, which does require a neutral connection, but is compatible with any load within its ratings as a result of not having to trickle its own operating current through the load.