The Reason why CFL bulbs flicker

If you’ve always wondered why your CFL bulbs flicker when they should be off, here is the answer:


More info can be found here:


There were some discussions about relay switches on this forum before. The problem with those is that they require neutral, which is not always available in retrofit situations.

I use the ZRW113’s anywhere I have a CFL or normal FL tube. These work like a champ. Instant on/Instant off. No flickering at all!

That’s true. I had to fish a neutral up the walls on the main floor from an unfinished basement to the switches in question in order to complete the circuit.

No problems? How is your house wired?

standard wiring…1 line, 1 load, neutral, and ground. The switch is really easy to wire: white goes to neutral, green to ground, black and 1 blue goes to the line, and the other blue to the load. Did not use the yellow traveler wire, and the brown wire is a do not connect.

The only complaint I have is this has a mechanical relay, so you hear it switch the load.

hmmm… Sounds like you have a better wiring setup in your home. Is it new?

My House is 100 years old with updated copper wiring and upgraded to a 120amp service. As an example: In my foyer I have a black (hot), white (Neutral) and copper (ground) like you are suppose to but the wires are connected to the light fixture first then it comes back down to the switch. Therefore my neutral is just caring the current back to the fixture to power the light. So, I had to add an actual neutral to complete the circuit for the switch itself. I think we both have normal wiring but yours is better suited for this application. Where I had to do a work around. I’ll be getting a new switch soon from Leviton. So, I’ll be able to test it out in my situation.

I just bought a GE Dimmable CFL Bulb and put it into my light fixture and it works without flickering. So, the solution is to use the more “expensive” Dimmable CFL Bulbs if you don’t want your lights to flicker when they are off. I’m not using a dimming switch but at least the Dimmable CFL Bulbs don’t pick up on that small leak current. ;D

Do you use a relay switch? That would not have flickering problems. Normally flickering happens with dimmer switches. Or with non-relay switches - the ones which do not require neutral.

My switches are regular on/off relay switches. I’ve also got them hooked up with a neutral. I’m using the intermatic switches (HA18). They were cheap! About $40 CAD each, instead of $90 CAD for the next step up. I don’t have to say that $90/switch adds up quickly compared to only $40.

Most of these Z-Wave Relay Switches require the following setup: Power in to Switch - Out to Light. (See attached Diagram) Once again, the ground wire that is suppose to be there is absent for ease of understanding.

I have an older home (it’s all cooper wiring) and my wiring is setup as follows: Power Into Light - Switch Leg Down to Switch. (See attached Diagram) I have a ground wire, it’s just not in the diagram.

Luckily, without having to tare down walls… I was able to add an extra neutral to the switches by fishing a wire up the wall from my unfinished basement to complete the circuit.

Even though I have to buy a more expensive dimmable CFL bulb, my total cost is still much more cheaper for the same functionality.