I am finishing a room in my basement. I have wired a series of (5) recessed downlights on a dimmer switch. When I turn the dimmer switch to on, I notice a faint hum or buzzing sound on both the switch and each light. And the sound only intensifies when I dim the lights. I am wondering what might be causing this. Do I have too many lights on one switch? The (5) lights are 5" can lights each with a 60w bulb.