Melbourne: Flashing Street Lights? - Page 1
Forum section: electronics / general

author: EEVblog
author_rank: Unknown
timestamp: March 17, 2025, 04:50:26 am
content: Can anyone explain why street lights in Melbourne are flashing when the street power goes out?Not knowing the design of the lights or the control system, my guesses:1) If the power is genuinely off, then the lights must have a signifcant internal power source. Flicking caused by *insert reason here*2) If there is partial power still on the line due to some high impedance fault, then they could be stuck in a low voltage threshold startup loop. But I notice they are staggered, so seems more likely some other control aspect to it.3) There could be some illegal solar/battery install that didn't isolate fom the grid and is feeding power back into the grid, and then hiccuping or causign the light to go into some sort of fail safe mode.https://x.com/wtfinawtfworld/status/1901275291244454065

author: Andy Chee
author_rank: Super Contributor
timestamp: March 17, 2025, 04:55:47 am
content: I'm guessing brownout line voltage condition.But ordinary there'd be sufficient hysteresis in the lamp controller to deal with such an event?

author: Monkeh
author_rank: Super Contributor
timestamp: March 17, 2025, 04:57:59 am
content: Perhaps the HV isn't out and they're getting some capacitive coupling. Used to see a lot of that sort of behaviour with LEDs and two way switching.

author: EEVblog
author_rank: Unknown
timestamp: March 17, 2025, 05:11:40 am
content: Quote from: Andy Chee on March 17, 2025, 04:55:47 amIn that case I'd expect some house lights to be on/flashing too, but none are.

author: Analog Kid
author_rank: Super Contributor
timestamp: March 17, 2025, 05:52:49 am
content: Quote from: EEVblog on March 17, 2025, 04:50:26 amThat sounds like the explanation.I've seen signals here (in the US) go into a flashing mode when there's a power failure in the neighborhood; apparently there's some external power source (batteries?), and the flashing mode is because the lights can no longer be synchronized with the signals in the surrounding area (and a flashing red signal is the same as a stop sign).Now by "flashing" you do mean flashing at a regular interval, not flickering, right?

author: Muttley Snickers
author_rank: Unknown
timestamp: March 17, 2025, 09:32:41 am
content: We had a similar thing happen in early December whereby the street lights and certain appliances in the house were all going haywire as a transformer a few streets away was damaged. The TV would try and start then turn off again, the fridge light was on the blink along with other gadgets, as were all of the neighbours as well. I took a number of meter readings for posterity just in case any of our appliances got damaged by a surge when the power was finally restored. The mains voltages were fluctuating over a six hour period anywhere between 60 and 125 Volts AC, around 230V is what it should be normally. Fortunately, nothing was damaged as I decided to shut the mains breaker off at the fuse board until they repaired the problem transformer, I’ve never experienced anything like it before nor since.

author: tom66
author_rank: Super Contributor
timestamp: March 17, 2025, 09:50:09 am
content: I believe Australia uses TN-C-S wiring. A fault in the neutral to the substation transformer can cause widely fluctuating voltages. It can be dangerous as earthed appliances can go live. But in this case if an outage is caused by a fault PEN conductor then the earth will be used as the return path, usually properties and streetlamps do not have very low impedance earths, which will cause the phenomena of much reduced line voltage. This can be dangerous because the chassis of devices can be pulled above the potential of the earth itself, and is a particular concern for electric vehicle chargers. Anyway, this might cause streetlamps to malfunction if the cause of the outage is an open PEN.

author: jonpaul
author_rank: Super Contributor
timestamp: March 17, 2025, 11:16:52 am
content: Well know and common in lighting induster.At turn OFF, an LED ballast can contimnue to run and control ckt has some bounce as the bus voltage runs down.Depends on the LED ballast design.Worst are cheap chinese LED ballastsj

author: Halcyon
author_rank: Unknown
timestamp: March 17, 2025, 11:31:47 am
content: Quote from: Muttley Snickers on March 17, 2025, 09:32:41 amA similar issue happened to me just a few months ago. Most of Sydney and surrounds experienced hours of quite impressive storms over a huge area. Whilst we didn't lose power, something like 140,000+ premises across Sydney did. It was like someone let the bath plug out and the grid was struggling to remain stable for hours afterwards. I don't have any proper data, but I've attached the event log from the UPS. At one point it was switching every 20-30 seconds even long after the storms had passed. I thought it had developed a fault. I'd never seen anything like it.

author: SteveThackery
author_rank: Super Contributor
timestamp: March 17, 2025, 12:52:25 pm
content: Quote from: EEVblog on March 17, 2025, 05:11:40 amI wonder if it’s because some streetlights (the ones not upgraded to LED) use gas discharge bulbs, so some residual voltage might build up, trigger an avalanche discharge, and then repeat the cycle. Obviously few internal lights work in the same way.I dunno - it's probably rubbish but I'm just putting it out there.

author: TimFox
author_rank: Super Contributor
timestamp: March 17, 2025, 02:37:25 pm
content: Quote from: Analog Kid on March 17, 2025, 05:52:49 amThe US standard for traffic signal lights (red-yellow-green) is to go flashing red on power failure. By law, that condition is equivalent to a STOP sign. Unfortunately, drivers well past their license examination often forget that.It is also common for traffic lights controlling low-traffic intersections to be programmed for flashing-yellow and flashing-red (caution and stop, respectively) during late hours.

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: March 17, 2025, 03:05:41 pm
content: Quote from: EEVblog on March 17, 2025, 05:11:40 amQuite likely the streetlights are on their own dedicated circuit.A low voltage on this supply could cause this

author: tom66
author_rank: Super Contributor
timestamp: March 17, 2025, 04:20:08 pm
content: Quote from: TimFox on March 17, 2025, 02:37:25 pmIncidentally, the UK does it differently: our faulty traffic signal is all lamps out. This indicates that the junction has no defined priority. This creates interesting traffic problems, but a couple of junctions around here seem to flow a little better when people treat them as having no priority at all. Unfortunately, it will result in a higher accident rate.A few have signs at the junctions indicating that traffic should treat a faulty signal as being a stop sign but these are very rare (I've only seen a couple out of hundreds of junctions).

author: SiliconWizard
author_rank: Super Contributor
timestamp: March 17, 2025, 04:56:21 pm
content: Maybe they want to turn Melbourne into an open-air night club?

author: SteveThackery
author_rank: Super Contributor
timestamp: March 17, 2025, 05:39:35 pm
content: Quote from: tom66 on March 17, 2025, 04:20:08 pmIt has been joked that the UK should install faulty traffic lights at every junction, as it appears to bring out the best in people:"After you, old chap.""No, no, after YOU!"... and so on.

author: EEVblog
author_rank: Unknown
timestamp: March 17, 2025, 10:46:50 pm
content: Quote from: mikeselectricstuff on March 17, 2025, 03:05:41 pmYes, someone else on X suggested this. Seems to be the only explaination.

author: Analog Kid
author_rank: Super Contributor
timestamp: March 17, 2025, 11:46:25 pm
content: You never said, Dave: were the lights flashing regularly or flickering?

author: Andy Chee
author_rank: Super Contributor
timestamp: March 17, 2025, 11:57:18 pm
content: Quote from: Analog Kid on March 17, 2025, 11:46:25 pmDave provided a video link in his post.

author: Halcyon
author_rank: Unknown
timestamp: March 18, 2025, 12:00:59 am
content: Quote from: SiliconWizard on March 17, 2025, 04:56:21 pmThey already have all the drug problems and junkies that go with it.

author: Analog Kid
author_rank: Super Contributor
timestamp: March 18, 2025, 01:06:12 am
content: Quote from: Andy Chee on March 17, 2025, 11:57:18 pmSorry, missed that.But I couldn't view it. (Many problems here viewing videos on "X" for some reason.)Flashing or flickering?

author: wilfred
author_rank: Super Contributor
timestamp: March 18, 2025, 01:12:07 am
content: Quote from: mikeselectricstuff on March 17, 2025, 03:05:41 pmThe street lights on my street don't flash when the power goes out. We had a power outage a few weeks ago. It's one-in all-in on my side of Melbourne. Always has been for decades.Afterthought: I have old non-LED style street lights, but about a year ago one was replaced with a LED one. It is brighter and whiter but I did not notice whether it flashed or not during the recent power outages.

author: Andy Chee
author_rank: Super Contributor
timestamp: March 18, 2025, 02:07:29 am
content: Quote from: Analog Kid on March 18, 2025, 01:06:12 amI describe it as flashing at 2Hz, maybe 20% duty cycle. Multiple street lights were flashing, but unsynchronized.

author: Analog Kid
author_rank: Super Contributor
timestamp: March 18, 2025, 02:41:08 am
content: Street lights, not traffic signals.Scratch whatever I wrote about flashing traffic signals.No effing idea what that was ...

author: Halcyon
author_rank: Unknown
timestamp: March 18, 2025, 02:56:52 am
content: Quote from: Analog Kid on March 18, 2025, 02:41:08 amI did exactly the same thing yesterday. Eyes read "street lights", brain heard "traffic lights". I ended up deleting my initial post.

author: SiliconWizard
author_rank: Super Contributor
timestamp: March 18, 2025, 01:04:16 pm
content: Quote from: Andy Chee on March 18, 2025, 02:07:29 amMaybe they were just remotely updating the street lights' firmware and that didn't go well?

author: tautech
author_rank: Super Contributor
timestamp: March 19, 2025, 09:10:55 am
content: Quote from: Muttley Snickers on March 17, 2025, 09:32:41 amTypical symptoms of a dropped HV phase on the network transformer primary.Seen old old dropdown HV fuse go open with a boom like a shotgun and the LV supply go nuts for all those on the same transformer.Some appliances continue to run and their loading/unloading behaviour impacts on everyone/thing of the same supply.A Powerco network phase failure produces similar symptoms.Call centers sound amazed when you call and tell them what the fault on their network is and they can't see it.

author: RJSV
author_rank: Super Contributor
timestamp: March 21, 2025, 04:44:03 am
content: An older song has mention, (UK song), that 'The streetlights turning blue..tomorrow'.That's in 'The WIND cries MARY'1967

author: Analog Kid
author_rank: Super Contributor
timestamp: March 21, 2025, 04:54:32 am
content: Quote from: RJSV on March 21, 2025, 04:44:03 amAlmost.Jimi wrote "Thetrafficlights, they turn blue tomorrow".Quote

author: RJSV
author_rank: Super Contributor
timestamp: March 21, 2025, 05:55:49 am
content: Hahaha; I just got caught in the same trap as others, here , mixing up 'streetlights' with 'traffic lights'!