I’ve been exploring some electrical quirks with my new setup and I wanted to share my experience in case it helps others. The information on these forums was helpful to me, and I suspect my setups here are not unique.
I have knob-and-tube wiring that runs hot and neutral through the attic space and brings hot lines down the walls for switches. I have a few different setups (so far). All of these are without neutral. I’ll mention wattage, but wattage for LEDs can be kind of a misnomer since they all leak differently when off. I am using the Aeotec bypasses, so far.
- The first is a single pole switch with 4 Hue A19 White & Color 1100 lumen models, ~40W total. No bypasses needed when at least 3 bulbs are in circuit and smart dimmed to 0%, but the switch fails when only two bulbs are in circuit and smart dimmed to 0%. No bypasses tested.
- The second is a single pole switch with a pair of 8.8W Feit dumb bulbs. One bypass needed for switch operation. (Not dimmable.)
- The third is a single pole switch with a single “7.2W” Feit dumb bulb. One bypass needed for switch operation. (Not dimmable.)
- The fourth is a 3-way switch with an Aux and a single Hue 6" downlight, rated at 12W. One bypass needed for general operation, and smart dimming above 50%. 2 bypasses needed for smart dimming down to 10-15%. At 3 bypasses, the bulb can be smart dimmed to 1%, but the switch fails when the bulb is smart dimmed to 0%. At 4 bypasses, the switch functions in smart mode, although the LED bar gets some flickering when it runs at 100% brightness while the load bulb is off.
- The 5th is a single pole switch with the same 6" Hue downlight rated at 12W. A single bypass allows switch operation with the bulb kept above about 40%. A 2nd bypass allows the bulb to get down to about 10% without the switch failing. A 3rd bypass allows full operation of the switch as long as the LED bar is kept below 50% brightness. (The switch fails when flashing for mode changes, for instance.)
A few conclusions:
- The Hue downlights are not very leaky and add a decent bit of impedance at 0%, requiring about 2 bypasses to keep the switch powered when “off”.
- Similar story likely for the Hue bulbs.
- Another angle of the above is that cutting power to the Hue lights also cuts their draw, behaving similar to a dumb bulb.
- The Aux switch seems to require a bit less than one bypass, as my 3-way operates a hair better with 4 bypasses than my single pole does with 3.
- The LED bar actually has some power draw. Is there a parameter that caps its max brightness?
I’ve ordered the Fibaro bypass, which I’ll test when it arrives. I’m hopeful it has a bit less impedance than the Aeotecs. I might also try a load resistor rated up to a few watts, but I’m more likely to just accept the cost and put these bypass capacitors in parallel until the combined impedance is low enough for switch operation.
Thanks to all the super-posters who answer questions. In particular for this post on a 3-way no-neutral installation. I had the same setup, with Line + 2 travelers in one box and Load + 2 travelers in the other. I un-wired the old switches, used a non-contact voltage tester to find the hot Line with the power on, then used my multimeter and some speaker wire to sort the travelers out, and finally wired it all up. The bypass excitement came later.