I don't have many light-dimmers in my house right now, but I'm doing some renovation, adding recessed lights in some areas that I have temporary open access to the floor joist areas and circuit runs, and I'm noticing some radio-unfriendly behavior in the first dimmer I've installed.
I've been looking on digikey for "power line filter modules" and yes they have hundreds of them. They are all, I believe, designed to be installed in appliances and devices of all sorts, inside their respective housing, enclosure or cabinet, and wired on the power-input side of the device. This is presumably to prevent wide-spectrum electrical noise from traveling back from the device to the branch circuit and hence causing the entire circuit to act as a broadcast antenna.
Most of these filters range from $15 to $30, come in a variety of inductance and current ratings, are all housed in a metal can with mounting tabs, have connection options such as spade tabs, screw terminals or posts, or wire leads.
So my first observation is that none of these is what I would consider to be mountable as infrastructure devices that you might locate in an inaccessible place, such as you would a junction box, even if the device is electrically "safe" from a durability / longevity point of view. So if I wanted to use one of these on the input side of a dimmer control for a dimmer controlling say 4 lights, and potentially also put one on the output side (?) I think I'd want to mount them inside a junction box, which is not difficult. Even if these devices have MTBF ratings in the hundreds of thousands of hours, I do wonder about the really long-term installation of these devices in areas that would be somewhat difficult to reach years from now (behind walls, under floors, etc).
So besides where on a circuit these filters should or could go to achieve maximal EMI/RFI filtering effect, I was wondering if anyone else has used these particular devices for this purpose.
Or am I overlooking purpose-built infrastructure-mountable or load-center panel-box mountable products that are easily obtainable, reasonably priced and equally effective?
Best Answer
The problem with those modules is they're designed to go in a product
The power-line RFI filter modules you're looking at aren't useful for what you're trying to do. Why? Because they're designed to go in a finished product, and thus are UL Component Recognized (with the RU, or Rather Useless to us, mark), vs being UL Listed as something that can be installed standalone into mains wiring.
(If you can find someone willing to sell you one, there are UL listed facility EMI/RFI filters available; however, most of them are either combination EMI filter/SPD units, and those that are standalone EMI filters are rather hard to find/obtain. Furthermore, heavy-duty facility EMI filters have relatively high line-to-ground leakage currents, which makes them not get along well with GFCIs and many AFCIs.)
However, there is something you can use to fix this
However, if your dimmers are emitting RF noise, you still do have a couple options. First off, upgrading to better quality, specification grade dimmer switches (such as the better stuff Lutron, Leviton, Eaton/Cooper/Arrow-Hart, or Legrand/Pass & Seymour make) will often get you dimmers that go the extra mile on built-in RFI/EMI filtering. If that's insufficient, one can try a Lutron Lamp Debuzzing Coil in series with the dimmer wiring, as per Lutron Application Note 519.