Bypass for a 10W smart bulb + Blue

My questions are:

  • what are the chances that this setup will work without a bypass? I see the manual says anything less than 25W requires a bypass, but it’s not clear to me if that’s only for multi-way setups or for single pole setups too and. Asking because wiring up a bypass is way harder than usual in my house

  • is a bypass needed when using in smart bulb mode at all? This thread implies it is not needed, and that makes sense in principle

Thank you!

I would say that it’s slim to none. 10W is not enough for the switch to be able to leak power to stay running. The bypass will create a constant load which will allow the switch to be able to leak enough power to operate. It’s necessity should not change with multi-way or single pole setup.

That’s an older thread for the gen 2 switches. I’ve seen several threads recently with the gen 3 (2-1 blue or red) that have required bypasses in smart bulb mode for stability in the non neutral setup.

Sorry, I’ve got no idea here. I haven’t actually needed to run one myself.

Since you’re running in smart bulb mode, you may be able to rewire at the light fixture to send a hot + neutral back to the switch (eliminating the switch leg) instead. It might be easier than trying to get a bypass installed.

Thank you for the detailed response, and it sounds like I’ll definitely need a bypass or equivalent then.

Doesn’t this involve fishing a wire through drywall and ceiling? If so, that would be impossible for me. If there’s an easier way, please do let me know.

If rewiring is impossible, I guess my other options would be:

  • to use a Lutron Caseta which doesn’t need a netural (but doesn’t support smart bulbs)
  • or to permanently tie together the line and load wires, and use a battery operated Zigbee switch or similar?

No. It just requires rewiring at the light. Instead of using the two conductors between the switch and the light for the switch loop, you use the two conductors to send the hot and neutral from the light the switch. This leaves the light constantly hot but provides a hot and neutral at the switch box.

@autobahn – I can sympathize with some fixture locations being a pain to access, so if it’s possible to open it up and leave things exposed/hanging temporarily to experiment, I’d try a bypass first. A bypass is the least “intrusive” option in terms of having to undo or remediate anything in the future.

If the bypass is unsuccessful, then I’d next try Bry’s rewiring option above.

Thank you @Bry and @hydro311!

With my situation, the order of difficulty is:

  • Anything that involves opening up ceiling/drywall (virtually impossible)
  • Rewiring at the light fixture (bit of a pain, but doable)
  • Rewiring at the switch (no problem)

Also, I’d actually prefer to not have a bypass since I want to do this to many lightbulbs, and am concerned about the additional power usage.

So given all of this, I don’t mind trying to rewire at the light fixture at all. However, I don’t know exactly what needs to be done there. A search brought up this thread and @Bry’s post there seems to also recommend the same approach. But what I have trouble understanding is what needs to be done at the light fixture.

I haven’t opened up my light fixture yet, but it’s an older house, and what I imagine is, ignoring ground, there are two wires: neutral, and a line (hot). The line would come from the switch.

What would I need to do at the fixture given this? I’m guessing I’m mistaken about what I’d find in the light fixture? If there’s a circuit diagram or a howto that anyone can point me to, I’d be most grateful. Thanks a ton!

Based on your description, at the fixture, you’ll likely have something called a switch loop:

You can see that the power source comes to the light fixture, then the hot wire is sent over one wire (the white in the diagram) to the switch where it returns from the switch on the black wire.

You can rewire to make the fixture constantly hot (connect the power source line to the fixture directly) and then connect the two wire going to the switch to the hot (black) and neutral (white). This will give you a hot and a neutral in the switch box without having a switched hot (load) going back to fixture.

Ah, makes perfect sense now! Thanks a ton @rohan for the image + description, most appreciated! Now to go do it :).