Heard popping sound and saw a flash after a thunder strike near my equipment - Page 1
Forum section: electronics / general

author: FlevasGR
author_rank: Regular Contributor
timestamp: May 21, 2020, 08:21:34 pm
content: Hello all,Today i had the worst experience of my life (yet). The power went down and as always i flipped the switch which is located on the outlet (Australian outlets) to avoid high voltage once it comes back. I didn't think to pull the cord because it was just a simple power outage. That was the main outlet by which my computer, my server and my networking equipment draws power from.Within few minutes thunder strikes started popping right and left and i totally forgot that i was still connected to the wall. I know that i may be over-reacting but even with a single thunder strike i always shut down everything.At some point i saw a blue flash and heard a popping sound near the shelve where my networking gear is and right after i heard the sound of the thunder strike. My heart dropped to the floor. I knew that something bad had happened to my stuff and i could not wait for the power to come back to test and assess the damage.After half an hour the power comes back and after waiting for 15 minutes to make sure that everything was okay i plugged everything back and flipped the switch. Ty my surprise, nothing was damaged. Both switches, my server, my pc and my access point were functioning as intended. I still cant wrap my head around what happened. I don't really have good protection yet. Only a single, decade old, Belking surge protected power strip.I feel very uncomfortable not knowing what happened.Do you have any ideas what caused the sound and the flash?Note: All windows and blinds where closed. It didn't came from the outside.

author: engrguy42
author_rank: Frequent Contributor
timestamp: May 21, 2020, 08:33:40 pm
content: The thunder sound you heard was extremely high voltage lightning. It can hit the utility wires and set up a very fast (microseconds) extremely high voltage wave travelling and bouncing all over the power system from the point where it strikes.The utility has "lightning arrestors" placed at various points on the power lines. These are typically MOV's (metal oxide varistors) that are basically nonlinear resistors that will act as a very low resistance to super high voltages, thereby shunting those high voltages to ground. Older ones are just like arc gaps that shunt the wave to ground.However, sometimes there's no MOV around, and these travelling waves of high voltage can bounce around the power system, and when they hit a high impedance they can even double in magnitude.It's possible one of those waves got past the transformer feeding your house and into your 230V wires and into your house. We're talking maybe thousands of volts in a wave that lasts maybe 10 microseconds or something. ZAP!! Your wall outlets and switches might not be rated for something that high.BTW, don't count on those surge arrestors in the outlet strips. Often they tend to respond so slowly that the damage is done before they wake up.

author: FlevasGR
author_rank: Regular Contributor
timestamp: May 21, 2020, 08:44:01 pm
content: Quote from: engrguy42 on May 21, 2020, 08:33:40 pmWell, isn't it weird the no damage was made? I don't trust these strips either and the switch on the outlet will definitely not prevent high voltages from arcing over.

author: engrguy42
author_rank: Frequent Contributor
timestamp: May 21, 2020, 08:48:48 pm
content: Keep in mind a lot of electronics devices in your house have their own MOV's internally for stuff like this as well as other overvoltage protection. And the high voltage can flash over to ground at any point in your house wiring, so it might not even get to the important stuff.But whenever I hear the boom-booms start I go unplug all my computers and electronics and stuff.

author: Syntax Error
author_rank: Frequent Contributor
timestamp: May 21, 2020, 09:01:31 pm
content: My theory, a nearby lightning strike may have electrified your building, and even the air inside your room. So the blue flash was real! Your kit would have escaped because it's casing was at an equal potential to the electrified air. The popping sound could have been the charge finding it's way to earth - a bit like the way static used crackle away when a cathode ray television was turned off. Isn't nature shocking?P.S. you might be able to your storm event here:http://en.blitzortung.org/historical_maps.php?map=22

author: engrguy42
author_rank: Frequent Contributor
timestamp: May 21, 2020, 09:21:17 pm
content: Quote from: Syntax Error on May 21, 2020, 09:01:31 pmYeah, I'm sure the blue flash was real, but since the OP said it flashed on the shelf near the networking gear, I'm guessing that it was a voltage surge flashing over on the wires coming from the wall outlet into the gear.And yeah, that's the other version of the website I use ("lightningmaps.org") to track realtime lightning as it comes thru the area. Pretty slick. Usually when there's a storm coming thru I'm locked in front of my computer watching the realtime strikes, and when they start to get close I jump up and unplug everything.

author: edpalmer42
author_rank: Super Contributor
timestamp: May 21, 2020, 09:34:32 pm
content: Some equipment has internal spark gaps to help protect it. Dave has shown these in previous videos. That might have been the source of the flash.The popping sound could have been an internal MOV exploding as it sacrificed itself to protect the equipment. Your equipment survived, but now is running with no protection. For peace of mind, you might want to do some disassembly and inspection. Look for blown components or scorch marks near the point where the power line enters the unit.

author: Syntax Error
author_rank: Frequent Contributor
timestamp: May 22, 2020, 12:01:57 am
content: From an early age I was taught to always unplug the TV coax when a storm was close - always! Possibly my first ever electrics lesson? These days, if we're expecting a direct hit, I'll take out the DSL cable. Online storm tracking makes prediction so easy, but it doesn't beat DFing a storm with a long wave radio, old skool.@FlevasGR <- did you smell anything like strong ozone or an electrical component had overheated?Another remote possibility, ball lightning came to play.

author: engrguy42
author_rank: Frequent Contributor
timestamp: May 22, 2020, 12:38:47 am
content: Quote from: Syntax Error on May 22, 2020, 12:01:57 amOr maybe a zombie attack with laser strikes from the mother ship.

author: jmelson
author_rank: Super Contributor
timestamp: May 22, 2020, 01:50:02 am
content: Quote from: FlevasGR on May 21, 2020, 08:21:34 pmYou might check your surge protectors to see if they are still OK. What may have happened is they sacrificed themselves to absorb the surge induced on the wires, and are now no longer protecting your equipment. Unfortunately, they are not that easy to test. But, if you open them up and see the MOVs have exploded, then you will know. (That might void the warranty.)Jon

author: Cyberdragon
author_rank: Super Contributor
timestamp: May 22, 2020, 04:56:50 am
content: Quote from: Syntax Error on May 22, 2020, 12:01:57 amCould also have been St. Elmo's fire arcing off of something, basically just stray EHT static that made it into the house.(it can manifest as mini-lightning bolts not just little fizzy corona discharge). If it was ball lightning, the equipment was damn lucky to have survived (it's usually pretty nasty).

author: Berni
author_rank: Super Contributor
timestamp: May 22, 2020, 05:37:43 am
content: Yep sounds like spark gaps or MOVs inside your equipment, surge protectors, extension cords...etc might have sacrificed themselves to protect your gear.You can count yourself being lucky since with a lot of serious lighting strikes these protection devices tend to just limit the extent of the damage rather than prevent it completely, large ethernet installations are particularly vulnerable. I would definitely have a check on what is left of those surge protectors, or just play it safe and buy brand new surge protectors to plug your stuff into.But yeah lighting can easily produce transients of voltage high enough to jump across switches in the off position, so just flipping a switch is not guaranteed to stop it (But still will stop it in a lot of cases). I personally don't switch anything off in a lightning storm and yeah lost some stuff to lightning but never anything major (Apart from the rather expensive heatpump that blew its VFD module that can't be unplugged anyway since its directly wired in)

author: Syntax Error
author_rank: Frequent Contributor
timestamp: May 22, 2020, 09:50:19 am
content: Yes, ball lightning is a bit dramatic, but I agree St Elmos fire is a likely suspect for the unexplained electrical phenomina. Any cyborgs seen walking around the neighbourhood?Spark gaps only work if there is a potential difference across the gap. In the case of telephone wires, the transient current from a local lightning strike has a habit of running along both the A and B wires, so Vdiff is close to zero. Thus destroying what ever, or who ever, is on the other side of the 'drop wire'.

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: May 22, 2020, 10:32:35 am
content: As well as any surge protection devices, it could also be caps in input filters that got damaged, which would also not stop the equipment working

author: engrguy42
author_rank: Frequent Contributor
timestamp: May 22, 2020, 11:10:00 am
content: Quote from: mikeselectricstuff on May 22, 2020, 10:32:35 amUnless they got shorted by the voltage spike...which might cause the input fuse to blow...which would mean the equipment won't turn on...Or maybe the components shorted then blew up real quick, causing an open circuit...and the fuse didn't have time to blow.Or maybe the components have MOV's in parallel, and the MOV's handled the spike...or maybe they shorted first... but that would mean the fuse would blow...unless it didn't have time....The list of hypotheticals goes on for miles...

author: FlevasGR
author_rank: Regular Contributor
timestamp: May 22, 2020, 11:49:03 am
content: I've been opening all the gear and sniffing itNothing out of the ordinary yet.

author: engrguy42
author_rank: Frequent Contributor
timestamp: May 22, 2020, 11:55:31 am
content: Quote from: FlevasGR on May 22, 2020, 11:49:03 amJust be careful...those St Elmo's zombies can hide anywhere...BTW, if there's a wall outlet (power, network, etc.) near where you saw the flash maybe take a look and see if you see any black spots. Just don't touch anything.

author: FlevasGR
author_rank: Regular Contributor
timestamp: May 22, 2020, 01:16:53 pm
content: Quote from: engrguy42 on May 22, 2020, 11:55:31 amI'm well prepared. I sprayed the equipment with holly water.

author: Cyberdragon
author_rank: Super Contributor
timestamp: May 24, 2020, 04:43:59 am
content: Quote from: engrguy42 on May 22, 2020, 11:10:00 amAnyone who's delt with exploding Rifas knows that high end gear never puts the fuse before the damn input filter. Nah, that would be way to nice...

author: RoGeorge
author_rank: Super Contributor
timestamp: May 24, 2020, 09:49:16 am
content: Could have been worst, like this Anomaly from Metro!