Walking the dog around the block, a few days ago we noticed blinking exterior lights on a house behind us. These are “coach lights” on either side of his garage door. The blinking seems to occur at a constant rate, rather than an irregular flickering (or morse code!)
First, both lights were blinking. Then, on a subsequent day, both were on but neither were blinking. Then, only one was blinking. Today, only one was blinking, and it was very faint. When I got inside my house I happened to look out my back windows and noticed that the similar light next to the same house’s back door was blinking.
I tried googling, but all I could see suggested loose wiring. Which I didn’t understand how it could be on and off again, and affect different lights on different days. If it matters, the weather has varied over the last week, from down in the teens F, to low 40s F this morning.
I had thought it might be something like an LED bulb signalling that it was getting old, but I did not readily see that on-line. Nor would that seem to explain the changing blinking of different bulbs.
If the fixtures contain a motion detector or photocell, they might not be compatible with a standard LED bulb; the bulb would get “confused” and might flicker. Just a thought.
I’m trying to think how a single loose wire could affect three different light fixtures in different ways. I wouldn’t think the garage door lights would share conductors with the back door lights. (It’s possible I’m misinterpreting the OP’s description.)
In a somewhat related experience, one of my rural neighbors had a set of three coach lights along his driveway. The road was not well-lit and the house was pretty far back from the road. Rather than put a HUGE house number on his mailbox, he put one of those old-fashioned blinker units in the light closest to the road so he could tell people expected at night to turn in at the blinking light.
LEDs can flicker if the fixture isn’t fully compatible with them. They actually need fancy circuit to “stay on”, and without that, they flicker with the alternating current. There’s probably something not quite right in the circuitry, that is working intermittently.
No idea about photocell, but there does not appear to be a motion detector. Right now on this overcast day the back light is off.
The blinking is clearly NOT a random flicker.
Not sure how I can explain it better. House is a 2-story with basement on a north/south street. House is longer (north-south) than it is wide (east-west). Brick lower level, frame second story. 2 carriage lights are on the front facing east. The 2-car garage takes up the northern third of the house. Garage door faces east.
Back door is off the kitchen, facing west, right about in the middle of the back of the house. Carriage light to the south of the door is similar style to the 2 on either side of the garage.
Thank you. I think I understood it correctly the first time. I was straining to think what conductors a lighting circuit would share in both areas that could still affect three fixtures in three ways.
I think that the suggestion about LED fixtures (perhaps affected by cold temperatures?) would behave in such an intermittent manner.
This is by far my first guess. Your standard el cheapo LED bulb can’t handle cold temps. The worst the design, the less cold is takes to make them blink.
Even outdoor LED fixtures have this problem. I see it all the time here during the winter.
When LED bulbs start to die, they often fail by blinking at a pretty regular rate. You can often see street lights doing this.
The actual failure is in the power supply, not the glowing parts. Which is why the whole thing blinks or flickers.
There are security lighting systems that blink, but do so intermittently. It’s a deterrent to homeless sleeping there. The sometimes yes sometimes no is annoying as hell and supposedly drives them elsewhere. It mostly just drives tbe neighbors nuts.
It sure sounds like voltage drop in the wiring. If you have 140 Watts on a 12 volt system, that’s 12 amps. That is a lot of amps! If your run is 100 feet, that’s 200 feet of voltage drop (assuming all the load is at the end, which it probably isn’t). If you used 12 gauge wire for 200 feet, that is about 0.3 Ohms, which doesn’t seem like much, but multiply that by 12 amps and you get a voltage drop of 3.6 Volts. LEDs have a nonlinear output characteristic and require more voltage when they are hot. My guess is that you dropped the voltage to the point that they go on, but immediately heat up and turn off, which repeats in a thermal relaxation oscillation.
To the OP: are the lights in question new? Could they all be on the same stretch of cable? If so, it could be a voltage drop. But if they’re existing ordinary fixtures that only just started acting up like this, it’s probably what everyone else is saying.
That is what I had thought. But I was surprised that it did not come up readily in my online search. Or in early responses here.
I had not noticed the exterior lights having been replaced recently - certainly not in the past week or 2. But I do not pay quite that close of attention. I do not know what “same stretch of cable” means." The lights are affixed to exterior walls, hardwired rom inside. I ASSUME the same circuit controlls the 2 garage lights, but can’t imagine how or why an electrician would have included the rear exterior light.
What do you understand the “consensus” reply to be? Something vague about LEDs not liking cold, and/or faulty circuitry, which reverses when temps rise and varies among similar fixtures? Not trying to be snotty. Just thinking if there is a straightforward explanation, I ought to be able to find a straightforward explanation more readily.
Yeah, this pretty much eliminates the voltage drop theory. In my case, all of the fixtures were on the same run of cable through the garden. The length of that cable run caused the voltage drop. It wasn’t 100% clear to me if what you were describing could have been like that, but obviously it isn’t.
Sorry, I was only offering a possible alternative theory that hadn’t been suggested by anyone else. That being shot down, I’m as mystified as everyone else, and less qualified to opine than many others here.
I had blinking and dimming LED bulbs when they were controlled by a motion detector. They did not draw enough current so the detector operated erratically. This was quite a few years ago when controllers were not designed to use LED loads. Maybe this person has recently swapped LED bulbs into an old system. External garage and porch lights would be good candidates for motion and photo cell controllers.
