As an electrician, I am sometimes called out to investigate why a client’s lights stay on when the switch is off. This can be very troubling or concerning for a homeowner as to what is wrong.
There are four main reasons why your LED ceiling light stays on when the switch is off.
- Low-quality LED or Compact fluorescent light bulbs.
- Faulty light switch.
- Voltage induction or capacitance in the electrical house cables.
- Bad earthing in the switchboard or the main house earth stake.
The easy fix is to replace the LED or compact fluorescent light bulb with a quality brand-name globe. In 95% of cases, this will fix the LED bulb glowing dim problem when the switch is off.
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The light bulb stays on when switch is off
If you have a faulty light switch then you will need to replace the switch by calling out an electrician to be safe.
Voltage induction of your roof cables is normal. There is not a lot you can do about this apart from separating out the roof and wall cables. Electricians should be spacing out the cables slightly in the roof during construction. Sometimes they get lazy and bunch them all together.
Bad earthing is another issue that could be either in the switchboard or down at the earth stake. Make sure that you have a properly grounded death stake that is not corroded. Check the earth cables that they are fastened securely and free of corrosion. Clean them up with a fine bit of sandpaper to improve floating voltages due to induction.
Make sure to turn off the power first just in case there is an earth fault.
The science behind this issue is due to the circuit voltage leakage to earth within the LED light globe. Most light switches only switch the active cable. But you can have voltage induction in both the active and neutral cables for a range of reasons.
The LED light bulb won’t be completely bright but dim when switched off due to induction power and earth leakage.
We actually have a LED hallway light that glows dimly when the switch is off. We like the feature due to the kids being able to see where they are going at night. But in the bedroom, this would be an issue. It is not dangerous as the induction or capacitance-voltage is very low.
As you can see from the globes above one is LED and the other is CFL. I prefer the LED lights around 13w as these give a nice bright room light. Especially is paired with a dimmer switch for mood lighting.
How to stop LED lights glowing when off
- Purchase high-quality LED or Compact fluorescent light bulbs.
- Replace a faulty light switch.
- Voltage induction or capacitance in the electrical house cables. Try to separate the power and lighting cable runs.
- Repair bad earthing in the switchboard or the main house earth stake.
The best way to stop LED lights from glowing when off is to reach into your pocket and buy some quality LED light globes. Not those rubbish cheap Chinese LED globes that claim to be as bright as the sun. But will possibly burn your house down after 3 months of use.
I buy these Sylvania LED light bulbs 13w (100W standard) that come in a 6-pack for a good price. They don’t have the led bulb glowing dimly when off issue. Plus they are dimmable and don’t flicker on low brightness.
The ceiling light stays on when the switch is off fix
I have found that it is often the ceiling light that stays on when the switch is off rather than the desk lamp with the same LED globe. This points more to cable induction and low-quality LED globes.
LED desk lamps are powered by power outlets and will have proper earthing unless the lamp is double insulated. I can get my desk lamp with a low-quality LED glob to light dim when the switch is off if I touch a metal part of the lamp. There is then a small earth leakage event to ground through me.
If you replace the ceiling light and it stays on when the switch is off then you most probably have a faulty wall light switch. In all instances replace the light globe first before fault finding further.
Led bulb glowing dim or flashes when off.
Some LED lights will discharge the voltage stored in a capacitor when they are turned off. This is why sometimes when you turn off a LED light it will flash brightly once when off. This is just a design flaw in the electrical circuit and nothing to be concerned about.
Sometimes if a LED light is located in a high humidity environment such as a bathroom, moisture will cause a slight earth leakage event to occur. This is usually in the form of a short current flow between some capacitors or resistors. This is a reason for flashing or dim LED lights when off.
Some quality LED globe manufacturers coat the internal circuit boards with an epoxy coating to prevent moisture ingress issues.
Is LED ghosting dangerous?
Generally LED ghosting is not dangerous but you need to work out why the light bulb glows when switched off.
If it is due to the substandard control electronics of the LED light then apart from being annoying with a dim glow the light is perfectly fine.
The below video explains why some LED lights keep glowing when switched off. Learn math and science in a fun way about this phenomenon.
Why do some lights glow when turned off?
Some cheap LED lights will glow when turned off due to voltage leakage in the light globe. This is becoming a big problem with the cheaper light globes that are flooding the market.
A LED light globe that has been well made with quality components should not face the glowing problem when the light switch is off. This is due to the full-bridge rectifier, capacitors, and resistors that are installed in the electrical circuit.
The above image is of a full-bridge rectifier that is installed in some LED lights. There may be some other components like resistors, capacitors, and step-down transformers to lower the voltage of the LED light that will improve the design.
Over time you can still have an issue due to the failure of internal components such as a diode or capacitor that could cause voltage leakage to the LED light.
Some cheap LED lights will have a half-wave rectifier circuit that is prone to voltage leakage and light leakage. This is a big reason for why the light bulb stays on when the switch is off. They also have a bad flicker problem that many people can see. This can cause headaches and problems focussing with your eyes.
This post will help you how to fix LED lights that flicker or have a buzzing sound.
Lights turning off and on by themselves
If your LED or CFL lights turn off and on by themselves then this is often due to a faulty control circuit. Or you could have an overheating transformer. Most LED step-down transformers will have an overload or over-temperature switch located inside.
On hot days or if the LED driver transformer is underrated it can trip out. This will cause the light globe to turn off. Once it cools down again the light will turn back on again for a while. Until it trips out and turns off again, the cycle continues forever.
Some compact fluorescent light globes can also have this problem. The only way to rectify it is to replace both the LED light and transformer or the CFL globe.
If you find that the lights turning off and on by themselves with the switch off then you most probably have a faulty light switch. This wall switch will need to be replaced by an electrician.
Conclusion
We have a mixture of LED, compact fluorescent, and Philips Hue smart light globes in our home. By far the best lights are the Philips hue brand but they are slightly expensive. We like the features of color changing, smart turn-on-time features, and mood lighting. Philips Hue doesn’t have the problem of dim light when the switch is off.
I also don’t have an issue with our older compact fluorescent light globes. These require a higher starting voltage and tend to resist voltage bleed back better than cheaper LED globes. But I have heard people still having issues with CFL light globes glowing dim when off at the switch.
So if you are having issues with your light bulb staying on when the switch is off, then replace the LED globe with a new quality one. It should fix the problem.
I am a qualified Industrial Electrician for the past 20 years and I love to share my knowledge on home repair and maintenance jobs.
I love fast toys like Motorcycles, Cars, Jetskis, Boats, and Computers so writing about them is easy. Working on them is fun.
To keeps costs down I do all my own mods, repairs, and servicing. These skills I want to share with everyone. DIY is a skill everyone can learn.
