I connected this dimmer to a chandelier loaded with 12x 40W incandescent bulbs (480W total). The dimmer was easy to install, looked fantastic, and worked incredibly well, but it made an intolerable buzzing/zinging sound that could be heard clear across the room. The noise was emanating from the dimmer, not the bulbs, and was audible at all dimming levels except OFF, though it was quieter close to 100% brightness. This is a real pity, because there is much to like about this dimmer. My previous, rotary-style dimmer did not make any noise at all with the same chandelier and bulbs. Buzzing seems to be an issue with many forward-phase triac dimmers under certain load conditions, and it can vary from one dimmer to the next, even within the same model. On the other hand, ELV/reverse-phase dimmers are silent due to their mode of operation, so I looked for an ELV dimmer to alleviate the problem. Unfortunately, Leviton's SureSlide ELV dimmers are only rated at 300W incandescent, so I bought a 500W Lutron Skylark Contour ELV dimmer instead, which works very well and is truly silent, but it cannot match the sleek and refined style of the Leviton SureSlide. Update: Months after disconnecting this dimmer, I decided to connect it up again and hunt for the source of the buzzing. The dimmer seems well enough constructed, but, to save cost, as with most dimmers, the inductor/coil is not varnished or epoxy-filled as it should be, which can certainly cause 60Hz/120Hz switching vibrations to become audible, just as a speaker coil vibrates in a magnetic field. So, I glued the coil, and the buzzing/zinging has now been greatly suppressed, reduced to a low hum, which I can only hear when I bring my ear close to the dimmer. It is vital to use the right glue. Varnish or epoxy would work best for this application, but it's supposed to be sucked through the coil in a vacuum to fill every gap, which is impossible now that it's installed in the product. The coil is wound two layers deep, so the glue needs to penetrate ALL the way through the windings, bonding the wire to itself and to the core, otherwise it may continue to vibrate deep inside. I used Loctite 420 Penetrating Superbonder, which has a dielectric constant close to that of air. This superglue is thinner than water, which allows it to be instantly sucked into every crack and cranny by capillary action. If you want to try this, first DISCONNECT the dimmer from the AC power, remove 4 tiny screws from the black plastic casing, slide the casing away, and apply the glue to the coil. But plan carefully to prevent glue from getting onto ANY other parts. It runs faster than water, so tip the bottle sparingly and do not squeeze! Apply at each end of the coil, close to the core, then run a stripe or two across the coil until the windings fill with glue without dripping out. Use an absorbent paper towel to catch any drips. If this glue gets near the slider potentiometer, the dimmer will be damaged beyond repair. Allow the glue to cure for 24 hours, then reassemble and reconnect the dimmer. I'm now using this dimmer again, and I'm much happier with it.
