Just put some LEDs in kitchen fixture and I notice that when A/C kicks on they flicker (dim) noticably unlike regular bulbs. Is that normal?
LED dimming
- Thread starter cuffs054
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Not supposed to be normal but I've had hit and miss luck with dimmers for leds. Some work problem free, others flicker occasionally for unknown reasons.
Pete, I don't think he's talking about the use of a dimmer switch with these bulbs, but rather them dimming or flickering when the air cond. unit starts.
Cuffs, I noticed in your post about Alexa outlets that you mentioned your house is old, and most receptacles are of the ungrounded type. This leads me to believe your house may have outdated wiring.
Are you speaking of a central AC system, or a window/wall unit? Central air is always connected to dedicated 240 volt circuits, with usually one breaker for the compressor, and one for the blower and controls. Window type units if 240 would again have a separate circuit, but a 120 volt unit may not.
Momentary dimming of lights when heavy loads such as motors and compressors start is common, and nothing to be concerned about. However, if they stay dim (or continually flicker when air is running), then either voltage is dropping too low, or the AC compressor is causing a fluctuation in the frequency of the power.
Ideally, HVAC equipment should be served by it's own panelboard, with the wiring feeding it sized for the starting current of the largest motors that start at the same time. This will eliminate any noticable voltage drop, so no more light dimming when AC unit starts. Of course, the utility co. may also need to provide a larger transformer and heavier service cables to the house. All this is costly, so usually only done in large and expensive residences.
Perhaps the best thing to do is have an electrician visit, and check your wiring. They can measure the voltage drop when various loads are connected, and see if it is within an acceptable range.
Cuffs, I noticed in your post about Alexa outlets that you mentioned your house is old, and most receptacles are of the ungrounded type. This leads me to believe your house may have outdated wiring.
Are you speaking of a central AC system, or a window/wall unit? Central air is always connected to dedicated 240 volt circuits, with usually one breaker for the compressor, and one for the blower and controls. Window type units if 240 would again have a separate circuit, but a 120 volt unit may not.
Momentary dimming of lights when heavy loads such as motors and compressors start is common, and nothing to be concerned about. However, if they stay dim (or continually flicker when air is running), then either voltage is dropping too low, or the AC compressor is causing a fluctuation in the frequency of the power.
Ideally, HVAC equipment should be served by it's own panelboard, with the wiring feeding it sized for the starting current of the largest motors that start at the same time. This will eliminate any noticable voltage drop, so no more light dimming when AC unit starts. Of course, the utility co. may also need to provide a larger transformer and heavier service cables to the house. All this is costly, so usually only done in large and expensive residences.
Perhaps the best thing to do is have an electrician visit, and check your wiring. They can measure the voltage drop when various loads are connected, and see if it is within an acceptable range.
CircleW, you are correct in your assumptions. It's just a momentary dim when central unit starts. It just surprised me since the old incandesents didn't do it.
>> It just surprised me since the old incandesents didn't do it.
They probably did, just that it was less noticeable.
Incandescent lights have a slower reaction time when turned on or off, as the electricity is turned into light by heating the filament until it glows. That hot filament has some thermal mass, and doesn't instantly cool down when the power dips or the switch is turned off, so it continues to produce light for some short period of time when turned off. Likewise, when the power is restored, it takes a small amount of time to ramp up to full brightness, making the turn-on less noticeable.
They probably did, just that it was less noticeable.
Incandescent lights have a slower reaction time when turned on or off, as the electricity is turned into light by heating the filament until it glows. That hot filament has some thermal mass, and doesn't instantly cool down when the power dips or the switch is turned off, so it continues to produce light for some short period of time when turned off. Likewise, when the power is restored, it takes a small amount of time to ramp up to full brightness, making the turn-on less noticeable.
I notice that the halogen torchiere in my living room dims momentarily when the A/C turns on (5-ton heat pump). The only time I use that lamp is when watching movies at night. I have not noticed A/C-dimming from the many LEDs that are now in use (A/C turned on a few seconds ago, the two 85-watt LED floods above/in front of me didn't dim).
However, there may be slight dimming (for the duration) when the electric tankless water heater triggers depending on how much power it draws for the required output. I can see the dimming increase/decrease if I increase/decrease the water flow at a tap, especially the bathtubs which are not flow-restricted, which increases/decreases the load and current draw on the water heater.
>> I have not noticed A/C-dimming from the many LEDs that are now in use (A/C turned on a few
>> seconds ago, the two 85-watt LED floods above/in front of me didn't dim).
Consider yourself lucky - you have lights with good enough capacitors on the power supply output to ride out those dips! Not all LED lights do, particularly the cheap ones.
>> seconds ago, the two 85-watt LED floods above/in front of me didn't dim).
Consider yourself lucky - you have lights with good enough capacitors on the power supply output to ride out those dips! Not all LED lights do, particularly the cheap ones.
