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Do Not Megger Alarms - what happens when 1000V is applied to a smoke alarm?
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- Опубликовано: 15 авг 2024
- What happens when using an insulation resistance tester on a smoke alarm at 500V and 1000V.
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It would definitely be a bit rude not to shove 1000v through it! 😂
.....But I want MORE!! I wanna get some toys out
(hint: upto 4kV with my variac and MOTs) and completely POP IT!
-Wayne's Electrical.
_22nd July 2020, 22.00_
Did I hear a " Photonic Induction" quote? lol
.....Maybe, maybe not.
The real question
that has to be
asked though, is......
.......Have you whacked the subscribe button on *_Wayne's Electrical?_*
If not, you're missing out on lots of electrical bits and pieces!
It's summer, and you know what that means: *_I WANT FLAAAAMES!_*
I can feel some *HIGH VOLTAGE* coming on and I need to fizz something over!
Of course, if you're not a subscriber, then you'll never know if-and-when that happens!
Stop missing out!
Please go to Wayne's Electrical right now, whack the subscribe button, activate the bell, and when a new video drops, you get to watch it first, with the other subscribers!
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:D
-Wayne's Electrical.
_24th July 2020, 22.45_
Bet it might pop if you reverse the leads. If there's a rectifying diode in there (which seems to be the case from the ~1MOhm reading) it may actually nuke it when the diode is forward biased.
@@mysock351C It's AC powered - so it would be biased both ways in normal operation..
The resistance seen is a discharge resistor.
I'd like to see the result if you went full Photonicinduction on it.
I could arrange that, no worries at all. I could ram
upto 4,000 volts into that thing, at quiiiiiite a few watts!
-Wayne's Electrical.
_22nd July 2020, 22.00_
@@WaynesElectrical Hey! You channel seems to be interesting but why did you disable rating and comments? Thanks! :)
Hiya. just to let you
know in reference
to thumbs and comments.
There are some......
......Videos which don't have comments boxes, because they are *_Five Minute Shorties._*
Those videos do have a cross-link to the Full Length video, upon which a comment can be posted!
*All full-length videos DO HAVE a comments box* unless it's a temporary video, or a trailer-vid which might be removed some time later.
As for thumbs.... ALL VIDEOS HAVE THUMBS ON THEM.
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Don't forget: If you watch a *_Five Minute Shortie,_* there will be a cross-link in the description of that video to the Full Length vid, which will allow you to then drop a comment into that related comments box. Others have done it...... You can too! :D
Subscribe to Wayne's Electrical today!
-Wayne's Electrical.
_24th July 2020, 22.58_
@@WaynesElectrical That might be because I'm not a channel, but a person? I've never watched your videos, and I made no comment on them. The first I've ever seen of you is running around the comments on this video begging for attention and trying to sound like Photonicinduction, and I made a guess that others might have had a similar, but less controlled, reaction to that behaviour.
I wish you the best of luck with your channel. Please, come up with some of your own lines, though..
But hey, to be polite, I've removed my speculation.
Joss sticks are a fairly convenient way of testing the smoke detection
Personally, I prefer toast.
Megger is a product brand name just as is Tannoy is brand not a Public Address system as is Hover.
True but I bet John is like the other 99% of sparks that say "I'm just going to do the meggering now", at least when he's not making YT videos. 😉 Or perhaps I'm just showing my age. 🤣
Sounds like me your glad you can still remember these good old names.
Petrol started off as a trade name, which is why UK legislation etc. calls it motor spirit
@Dusty 99 Hoover as in can't type. Keeping up the snark. :)
I think the danger scenario would be having two smoke detectors on different circuits sharing an interconnect wire. The interconnect wire is not designed to have any significant voltage on it relative to neutral, but if one were to leave one detector's neutral connected to mains neutral while the other detector's neutral was connected to a potential 500 volts above or below ground, that would put at least 250 volts between the interconnect and neutral wire on at least one detector.
BTW, I wonder how much it would have cost to use a moderately-high-frequency signal (e.g. ~50kHz-500kHz) on the interconnect as the alarm trigger, and then isolate it using Y1 caps? I don't like the concept of smoke detectors on different circuits using neutral-relative signalling in ways that can't tolerate high voltages. Among other things, if one has a smoke detector and another device at the end of a long circuit run, and that other device fails shorted, voltage drop on the neutral wire between those devices and the panel could cause it to reach a substantial fraction of mains voltage until the breaker trips. If one were to have two or more interconnected devices, and one had a neutral wire spike, what effect would it have on the other devices? Having it set them all off but not damage them would be reasonable. Having it destroy them in such a way that they sound continuously would be less desirable but perhaps almost tolerable. Having it damage them in such a way as to silently destroy their interconnect function would be downright bad, especially if the wires near the original detector got shorted as a consequence of a fire.
I’m ok with a Fluke then ? 😂🤓🤣
Interesting that it reads as such a high resistance. The best explanation I can think of is that the smoke alarm is using a capactive dropper and the capacitor is blocking the DC. So the resistance you measure is that if the discharge resistor for the dropper cap.
That's most likely, yes. The arcing was probably just across that little discharge resistor, and no harm is likely to have come to the alarm. Still, they're safety devices which are rarely tested at the best of times, so a warning label to try and avoid the mistake being made is reasonably prudent.
I doubt the capacitor is rated for 1000V, but it should be okay at 500V.
@@Mark1024MAK I wouldn't say it'd be 'okay' at 500V either, but the energy applied is limited so it should take prolonged exposure to seriously degrade it, and the backup battery is there to provide operating current if it is somewhat compromised.
Monkeh - a capacitor connected across the mains (which is what capacitor droppers effectively are) should be rated to withstand the peak to peak maximum mains voltage. The upper limit of a 230V supply is 253V. Hence the peak to peak voltage is 358V. So to allow a suitable safety margin, a capacitor rated at a minimum of 400V DC should be used. Although 500V is greater than the 400V rating, good quality capacitors for short periods of time should be able to withstand this voltage.
At 1000V, however, the voltage is two and a half times the rated capacitor voltage, so the likelihood of damage is significantly increased.
@@Mark1024MAK I haven't needed anyone to explain capacitive droppers or basic math to me in about 20 years, but thanks, I guess.
Could the warning be something to do with the interconnect wire ? you can interconnect across phases on these so it may damage that circuitry!
That Cliff QuickTest is really nice. I want one now!
Send it to big Clive to examine the cooked parts of it
#LetsPopIt - I miss Photonic Induction :'(
Yeah he had some personal problems apparently.
@@EgoShredder As in problems with a dysfunctional society which personally affected him, which nobody really cared about so now those same problems are affecting everybody
@@alakani Absolutely correct. I know some people get mad when the Jews are called out, but they do seem to have their tentacles in every single aspect of life, where money, power and control resides.
Love your videos John great explaination and very entertaining.. 😁
After seeing that "Warning: Do not Megger alarms" note in my fuse box I now know what this portentiously 'alarm-ing' 'Meggger-ing' is all about, so thanks, John!
Wow, that's the smallest radiation warning symbol I have ever seen on an ionising smoke detector label.
"Next time we'll take this apart and see what's inside." Please do NOT take the ionisation chamber apart. It contains a small amount of radioactive Americium 241. The ionising radiation is stopped by almost any amount of solid material, or even nitrogen gas in the atmosphere - the main danger comes from inhaling particles of americium 241 or contaminating your work area so it's fairly safe until you dismantle it.
The way it works: The alpha radiation from the americium ionises the air between two plates. The circuit inside the smoke detector periodically measures the resistance between the two very closely arranged plates (yes, many megohms). Ionised air has a lower resistance. Combustion by-products generally do not ionise as easily, and this results in a higher resistance between the plates, and the alarm is triggered.
Actually I suspect you are way smarter than I am and already know all this. Forgive me for stating all of the obvious 'just in case'- I'm only interested in having you around to make many more videos for us ;-)
As it made those fizzling noises connected up to the limited power output of an insulation tester I began to wonder how it would cope with a high voltage spike on the incoming mains and reflect on whether it got through compliance testing by the skin of its teeth...
Do not megger alarms
So JW does something mega alarming.
Uses 1000V
Hi John can you demo this with a proper Fire alarm smoke detector rather than home smoke detector such as an appollo xp95 smoke head (and include a fire alarm sounder) ..... as real fire alarms use FP200 which looks like mains cable, seen this happen a lot!
I once had to repair a 250KVA alternator that had been meggered by an electrician despite the warning that the diodes on the rotor had to be shorted first if you must megger the unit, hed obviously did not so the whole alternator had to be taken apart and new diodes fitted on the rotor.Expensive mistake on a brand new genset.
Please explain this piece of equipment.
Alternators don't have diodes.
If you want DC from an alternator, its output would have diodes, not the rotor, and if these were part of the alternator, it's output would be stated in kW. What was the power supply for the field ?
@@millomweb The diodes are on the rotor windings. Some alternators have two sets of windings on one shaft with a set of diodes between them, power from one or more of the stator windings is rectified and then fed to to a set of field windings via an AVC unit this produces a magnetic field which induces an AC current in the smaller rotor winding this is then rectified to feed the main rotor windings, it was these diodes mounted on the rotor that were blown. You obviously have not worked with brushless alternators of any size.
@@Equiluxe1 I guess there's a bit of permanent magnetism in there somewhere to get the whole thing started ! Interesting way of doing things - and you're right, brushless alternators are not something I've come across ! I'm probably a bit more 'old school' !
@@millomweb Always some residual magnetism in there. Brushless is old school now as it has been around since the 70's.The incident I referred to was in 83.
@@Equiluxe1 I don't think of th 80s as old school ;) Cars with dynamos were just nicely going out of fashion ! While no longer being fitted to new vehicles, older vehicles on the road still had them. Portable electric generators all had brushes - those and car alternators are my limited experience of alternators. Everything else was DC !
Hi! You say connecting brown and blue together and then measuring between those two and earth, will not affect the load, but isn't there (in electronic devices) often a capacitor or mov across live and earth or some similar arrangement?
That might potentially get damaged this way?
Anyway, thanks for the video!
The Y2 class capacitor used in this application is designed to stand off more than 1kV DC, so it won't be at all bothered. A MOV of course will break down and give you a low reading, but you're not putting nearly enough energy in to risk damaging one.
@@Monkeh616 Thanks for the explanation! I guess the only components that would be damaged by a megger would be actives like mosfets etc. You won't typically find these connected to earth.
And even when they insulation test a circuit between live and neutral, when there are still devices connected (like ovens for instance), then there's still a power supply of sorts in between those components and the 500V.
@@koffibanan3099 Series dropper capacitor power supplies could also be damaged by connecting between line and neutral, if the capacitor is not rated at a high enough voltage. They are used in some low wattage devices like small LED bulbs
"connecting brown and blue together and then measuring between those two and earth, will not affect the load" - was he just referring to this detector - since the Earth wire didn't go anywhere ?
Thanks John. Really useful video.
I'm guessing those alarms have a capacitive dropper for the mains side supply for it, so IR testing wouldn't really put a load on it (similar to some LED lamps). The crackling you could hear on 1000V test was prob the capacitor arcing between the plates. Of course the CPC was connected to absolutely nothing inside so is irellevant except as you say testing a full circuit and continuity of the CPC. I think manufacturer is just covering their ass on this, as the circuitry in the electronics could become unstable/damaged possibly, rendering it useless as a smoke alarm. cool video JW.
A capacitive dropper across mains needs to be able to support transients on mains. It also needs to fail safely - i.e. be a safety capacitor and therefore have an enormous margin of safety including factory testing at 2.5kV for 230V applications.
I'm amazed that a smoke alarm would fail when subject to 1kV from an portable insulation tester.
Like all mains appliances they must withstand surge according to EN 61000-4-5, and will have internal surge protection.
Now clearly the surge protection is intended to protect against transients and not e.g. temporary overvoltage. However a portable insulation tester simply isn't able to feed a fault into a MOV without tripping. And the internal circuitry of the alarm should be able to handle voltages lower than the MOVs clamping voltage for quite some time.
It is still a good idea to remove appliances before insulation testing. But given that portable appliances should be able to handle insulation testing by a PAT tester - who may be incompetent and apply a L-N voltage. I'd frankly consider a bit of life saving equipment such as a smoke detector that is incapable of handling this kind of misuse to be a pile of junk.
If it failed in situ, couldn't the high potential leak through the interconnect to other circuits ? Or is megging done totally isolated on all wires?
It's completely isolated, and interconnected alarms should be on their own circuit anyways.
Nice demo. This also applies to multiple mains outlet socket with neon indicator + plus switch since one of the L/N plus PE would trip the neon.? They could put "No HI-VOLTAGE on DUT" :P
Pretty sure if you ir the black ic terminal it fries the head so the alarm on its own will work but it won't interlink to others on the circuit
Nice video 👍
many thanks for the helpful video
If a 1000 volts do not work, one must do 1000 amps next!
I was a bit disappointed not seeing the insides, especially after the testing.
1,000 amps wouldn't do
anything either. To get this
thing to go crazy and achieve
poppage, you would need.......
.......Volts *AND* Amps!!
If John were to connect a mains-powered smoke alarm immediately after a house service fuse block, it would just sit there, waiting to do its job.
Yes, a smoke alarm connected directly to a 100A 240v supply. Not recommended, mind you! :D
To achieve poppage, it would need to be teeeeeaaaased with ever increasing voltage,
*_with some proper gruuuunt behind it_* and then, when it is finally pushed over the edge, all of those volts and current will escape out of the side of it in the form of flaaaaaames. :D
I have the toys to do this. A 28A variac, 4,000 volts of MOTs and 6,000 watts of ballasting should fizz this over quiiiiiiiiite nicely!
Of course, I wouldn't guarantee flames, as it only takes one component in there to explode, bust open the circuit and its game over. I have had THAT happen before now, which is extremely disappointing. Yes, I did go looking for my hammer! :D
So yes. Volts or amps on their own = nothing exciting.
Enough of both..... things get fizzy! :D
-Wayne's Electrical.
_25th July 2020, 00.05_
@@WaynesElectrical You can't get amps without volts is the very simple principle of Ohm's law most of us know. I expected people on this channel to know that.
Ben Baselet: ............ _"You can't get amps without volts"_
Mr. Photon: .................. Laughs at you in Amps.
Wayne's Electrical: ....... Here's what I have to say about THAT!
Some time back, I visited Mr. Photon. While I was there we.......
.......went to the Playroom and done some shenanigans with *LOTS OF AMPS!!*
Next, Click this. Watch lots of amps at virtually naff-all volts:
www. youtube. com/ watch?v=QMxNRjeJveQ
(Copy-and-paste, removing spaces to make it work)
We took an absolute MASSIVE stack O' amps and..... *_WE BLEW IT UP!!!! :D_*
There you go. Science. Job done. :D
-Wayne's Electrical.
_25th July 2020, 22.01_
Okay, I can use my Fluke multifunction tester instead if the Megger
Would you interconnect the alarms with 3C+E to the next alarm using black as the IC? Never done it myself so just wondering. If so would you need brown sheath on the black to indicate permanent live?
Yes, that's the usual method of installation, although the interconnect doesn't need sleeving as it's not a live wire - the interconnect still works when the alarms are on battery only, and there are several signals that can be sent on it.
In terms of low resistance devices I was thinking of heaters and motors.
Not naming names but someone at my company once knacked an electric shower by blasting 1000 volts between L-N.......
Thanks for sharing 👍
Is that then RWA Portable Appliance Testing Testing. Or does it mean you test everything twice. I bet you really do check the fuse value in each plug and those screws for tightness.
I’ve never seen that sticker and never had any problem testing these kind of circuits.
Meg Punt what voltage do you apply? Do you not get low ohms through L&N when testing smokes?
Nuzzi 500
What would be the danger in testing just between line to earth or neutral to earth (not line and neutral connected together to earth) if I’m honest I’ve tested like that for years without any problems, and never had an issue.
Most of the time the only difference is the need to do two tests L-E and N-E rather than just one LN-E.
If there was a N-E fault within the installation and you tested between L-E you would also be testing between L-N due to the fault, and that could damage things.
*_I WANNA POP IIIIIIIIIIIITTTT!!!!!_*
Only 1kV at 1-2 mA? *_I AIN'T 'AVIN IT!!!_*
I want flaaaaaames! Please send that here,
and _"Just-For-Fun"_ what I can do is to really.......
.
.
.
.
.
......Crank it _RIIIIIIIIIIIIGHT_ up, all the way to poppage!
I have a 240v, 32A supply, 28A variac, access to Microwave Transformers (MOTs) which kick out a good 2kV, and maybe even 4kV if re-configured to do so, and I tell you what, when *_The Mega Jiggy_* comes out for business and we get that thing ballasted on 6,000 watts and upto 4,000 volts, it isn't going to stand a chance! :D
Do you want flames? :D
Let's teeeeeaaaase it on the variac.
.....Uuuuuuntil it pops! :D
The only way it might survive, and that's if it has a MOV in there to protect against power surges.
But the question is.....
Even if there is a MOV inside the smoke alarm....... Could it withstand 4,000 volts being rammed into it at 6,000 watts for a good few minutes?
Probably not, and these things *_NEEEEEED_* to be tested out!
You know...... _"In-The-Name-Of-Science"_ of course! :D
So..... The question remains: You want flaaaaaames?
If you do, there is an Email contact on the Wayne's Electrical channel! :D
Thanxx for showing,
-Wayne's Electrical.
_22nd July 2020, 21.57_
Hi John, nicely done video!
7:15 what you stated is true in the test in this video and and yes P&N and CPC will test the wiring to the device without damage to it!
I was wondering about the cases where there are those filters(like you get with motorised white goods) designed to contain the motor noise and prevent it from invading the mains,
I have seen a connection involving X2 capacitors and coils which are connected to ground! I'm not sure what would happen if such a network were subjected to the test Volts!?
Megger between live or neutral and IC and see what happens.
Can you do a video on the difference on putting a hi pot vs megger. Would a hi pot damage it
Hi-Pot? How about 4,000 volts? :D I WANNA POP IT!!
I wanna get my toys out and crank it riiiiiiiiiight up. I WANT FLAAAAAMES!
-Wayne's Electrical.
_22nd July 2020, 22.04_
@@WaynesElectrical as in stolen photonicinduction lines? :)
What? No, as in.... I will get my
toys out. I will connect them to
a smoke alarm and then proceed
to gradually increase the voltage until...........
.......something exciting happens.
You know, like flames shooting out of the side of it.
Would you not enjoy that?
I know I would. :D
But, look at this! Look at how many more words (and thus time wastage) I have had to use to describe exactly the same thing.
*_IT IS NOT_* (as you put it) _"stolen-photonicinduction-lines"_ but merely a way of explaining it without beating-about-the-bush.
Get the toys. Connect it up. Crank it up. Right up. Tease it on the variac. Flaaaaaames! Poppage!
You want flames? You want poppage? The only thing I can say right now, is.....
Go to Wayne's Electrical.
BAAAAANNG that subscribe button.
GET THE BELL ON for when new vids drop.
MAKE SURE your subscriber perks are enabled.
Watch Wayne's Electrical videos.
Hammer the Thumbs Up Button.
Feel the Sssatisfaction. :D
There we are. Job done.
Cheers!
-Wayne's Electrical.
_24th July 2020, 23.50_
Like your channel keep it up for me
Try test Apollo smoke detectors
Have you tested how much power the mains powered ones use? For a lot of manufacturers you will be surprised (making ones with non replaceable batteries a much cheaper option often)
Dave Jones covered this in ruclips.net/video/_kI8ySvNPdQ/видео.html
Many devices--especially small ones--receive power from the AC line during parts of each cycle, but then return much of that power during other parts. In most cases where an electric customer has some small devices that do this, either that customer or other nearby customers would have other devices that would be able to make use of that returned power without it having to flow very far back toward the utility, and so most residential electric meters will deduct power returned from power received.
@Flat Finger Tuning is this what they call power factor or power correction factor and apparent power or am I wrong?
@@m3snusteve It's strongly related. If one were to measure the voltage and current waveforms and compute from the voltage waveform how much power would be consumed by a one ohm resistor driven with it, did likewise for the current waveform, took the square roots of both values, and multiplied them together, one would get apparent power.
If the ratio of voltage and current isn't constant, average power (which is computed by multiplying voltage and current at every point along the waveform and taking the average) will be less than apparent power, even if there's no point in the waveform where power is actually being driven back through the mains. On the other hand, if there are times when power is driven back through the mains, then actual power can be essentially nothing even when apparent power is quite large.
Who uses a megger on building wiring?
Everybody who owns one. That's what they are for.
@@jwflame I own several. I've only ever used them for machine tool wiring, like everyone else I know.
The fact that the megger has three leads - red, green, and blue - just like my Atlas DCA55 component tester, makes me want to test a transistor with it - on the 1000 volt range! 😆
It having three leads is useful for testing socket circuits and rcds.
So disappointed nothing blew up 🤨
Burning the toast is more fun.
So 1000v up it = CrackleOmatic 😂
Next video - a look inside the detector. Please answer my question: What are the two states of IC terminal ?
Thanks.
The interconnect isn't a simple two state connection, as this item: www.aico.co.uk/product/ei1529rc-hard-wired-alarm-control-switch/ exists to provide various remote functions where multiple alarms are installed.
@@jwflame Elsewhere, I found 'provides 9VDC on alarm' or equivalent - so thought 0V normal, and 9V as supplied to the sounders - BUT I guess different manufacturers offer different things - so I now guess alarms/detectors from different companies are not compatible !
From your link: "Interconnectable with other 180 Series alarms" - yeah - sounds like they're not interconnectable to other components offered by the same company ! Clearly, quite literally, no-brainers !
do not megger🤣🤣i hate when ppl says megger it...thats a fckin brand..should i saj i kewthech it...its called ins res test not MEGGER!!
hahah in after you
Ah yours use the same crappy power supply in them that the US versions do. 40ma of power running 24x7x365 is significant amount of power for such a device. Cheapest out there. I would gladly pay a dollar or two more for properly designed power supply. I have 12 smoke alarms in the house and each one draws 80mA of power according to specs and actual measured power draw is 65mA on the 120V AC line. Over the 10 year lifespan of the detector that is a lot of wasted power. My smoke detectors on my alarm panel only draw 50uA at 12VDC. That's a lot of kWh's per year for 12 of those vs the dc powered ones.
Please stop saying mains power you confusing the whole world