I had my house built last year and after moving in noticed that in our living room (6 led downlights) when we turn our lights on 5 turns on at once and the 6th one will be delayed ranging from 1/2 sec to 5 sec to turn on... the electrican came to have a looked last year but said its cause the 6th bulb was installed later so it takes longer to turn on (which frankly we thought was BS as we had downlights previously in our old house and always turned on at same time).

The switch controls the living room lights (6 leds), the alfresco (4 LED) and the external flood light, no dimmers.

Anyways it really wasn't big an issue, had someone else had a quick look but he couldn't really tell, so left it, a year pass and not longer is the light still playing up, also the dining and kitchen lights are being funny... taking longer then normal to turn on.

We had our 1year maintenance and totally forgot about the lights! I am concerned it might be the actual wiring behind that's the issue, can anyone advise if this is normal behaviour for LED downlights or if they reckon its more serious than that and we should call the builder back to have a look?

Thanks in advance, hopefully this makes sense to those reading!

  • 1
    Have you tried interchanging the 6th LED with one of the other 5 to see if the problem shifts? Also, try changing the LEDs in any other fixtures that exhibit the same problem. Frankly, I don't see how the wiring could cause the lights to turn on as much as 5 seconds later. It is more likely to be the LED bulbs.
    – Barry
    Commented Jul 30, 2015 at 0:11
  • Are the LEDs line- or low-voltage?
    – tariksbl
    Commented Dec 7, 2019 at 15:09

3 Answers 3


It's not the wiring. It's the LEDs themselves.

LEDs have a characteristic delay when turning them on which may be more than you're used to from a lifetime of incandescent bulbs.

Swap the LEDs from one position to another, and the problem should move with the bulb. Replace the LED with the equivalent incandescent (temporarily) and it should go away entirely.

Unfortunately, home LEDs are still relatively new and they suffer from both this characteristic delay --- which may vary from brand to brand -- and manufacturing variation --- where bulbs from the same manufacturer may vary, even within the same batch.

The only way to avoid these issues is to closely watch online and professional reviews (from trusted sources) to pick the better-performing brands; return any product to the store that is an "outlier" in the same room -- or, wait another few years for LEDs to mature (I'm serious) and just live with it for now.

  • 3
    Definitely varies from brand to brand. The cheapie bulbs take a moment to warm up; the higher quality ones haven't seemed to have that problem. It's an artifact of what kind (and quality) of power supply they're using.
    – keshlam
    Commented Jul 30, 2015 at 1:30
  • 1
    Unfortunately, lights are now 'technology' and have first adopter issues along with different performance from different vendors :(
    – AngerClown
    Commented Jul 6, 2016 at 13:17
  • Not all LEDs lamps have such a noticeable delay. As the OP recounts, older LED lamps seem to have designed the driver circuit to be at full brightness within a couple of AC mains cycles. I had great success with older Sylvania/OSRAM BR30s for our canned light fixtures. Unfortunately, the model I used is no longer available - and all of the replacements I've tried (Sylvania, FEIT) seem to need about 300 ms to (presumably) charge capacitors in their design. As of 2020, does anyone know of a brand still using the older approach that gives (near) instant-on?
    – JimMSDN
    Commented Sep 20, 2020 at 12:59
  • Also, you can seemingly tell if a lamp is going to have a delay: if the lamp feels like it has some mass to it, they always seem to turn on very quickly. The light-as-a-feather ones (in my experience) always have a delay. Unfortunately, I can't seem to find the heavy ones anymore. 8-(
    – JimMSDN
    Commented Sep 20, 2020 at 13:09

Are they on a dimmer? I run an electrical wholesale company and this comes up all the time. It's not the wiring it's the dimmer switch. Find out the brand led bulb (or led trim) and see witch dimmer is compatible with that brand. Then buy that dimmer and install it. All done!! :)

Ps it's probably a lutron AY-153P-wh

  • 1
    Lutron has a pretty good LED bulb selector. Obviously, these is geared towards Lutron dimmers, but the PDF 'report cards' on each bulb are probably useful enough to point out duds.
    – AngerClown
    Commented Jul 6, 2016 at 13:24
  • I don't use dimmers on any of my LEDs. Although dimmers could cause a problem (if they are "traditional" ones usually based on a triac), it is not always the case where dimmer = delay. digikey.com/en/articles/…
    – JimMSDN
    Commented Sep 20, 2020 at 13:06

I have LED bulbs all over the house. I have never had a delay; they turn on instantly. CFLs have a delay.
I originally had a problem as you describe, but that was due to an incompatible dimmer switch. No problems since the new switch was installed. Since you have no dimmers, it might be the on/off switch or the wiring.

  • How could a switch, which provides instant circuit closure, cause a delay?
    – isherwood
    Commented Aug 8, 2016 at 13:50
  • Nope. It's NOT the wiring or the switches. I have a variety of LED lights in our house. Some have delay, otehrs do not. It's more noticeable on the T8 LED 4ft replacements for fluorescent tubes.
    – 42-
    Commented Dec 18, 2018 at 20:43

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