Inside an old interference suppression plug. (schematic)

[@Tocsin-Bang]

Considering the probable age of this device it looks very well designed and made. Personally I'd be quite happy with replacing the varistors and using it again. Its a lot better than most of the junk you find today.

[@Chuckiele]

Well in any decent power supply of beefy devices, the input should look exactly like this, except for the odd MOV arrangement, but yeah, sadly thats not always the case.

[@todesgeber]

i'm no rocket surgeon, but that actually looked really well made. 3-piece case, ferrules, multiple protection modes...that hand taped pcb is pretty top too. i'd de-solder and clean the board so i could use it as "art".

[@station240]

It would make a very nice project case for mains project, except for the bit of missing plastic.

[@anditrev9327]

EMP was a specialist in lightning protection their main market was high-voltage distribution they applied that knowledge to their low voltage products

[@techy4198]

"The Gadget Mountain" sounds somewhat ominous yet simultaneously amazing.

[@benbaselet2026]

A fine lecture for noise suppression, if only school had been this entertaining :-)

[@discordiangod]

you're in the wrong program if its not entertaining enough

[@benbaselet2026]

Smartphone David I have always learned best alone reading and watching. A living teacher just disturbs my concentration.

[@mattmoreira210]

Anyhuw...

[@twistedsim]

Smartphone David This is pretty much the biggest group ever...

[@RWBHere]

Huw is the Welsh spelling of Hugh (or Hugh is the English way of spelling Huw!), and is pronounced in pretty well the same way in either language. Thanks for the video, Clive.

[@SeanBZA]

Failure mode of this is that one of the VDR units has shorted, or is breaking down at lower than expected voltage, and this then allows the spike to pass L to E instead of L to N when turning off the unit. Especially true of those older GE made zinc oxide varistors, replace with EPCOS silicon carbide units of same diameter ( determines power rating) and breakdown voltage and it will be fine again. I have a pack of those GE varistors where one at least breaks down at around 350VDC, and this fails the spec of needing 450V DC breakdown for the particular part. Never used, just failed from old age, but ones in service also exhibit the lowering of breakdown voltage with time till they go low resistance and pass heavy current, thus the thermal fuses to disconnect the power to the device when they go faulty, and the current is enough to heat them up a lot but not enough to blow the mains fuse.

[@Rosscoff2000]

Didn't Huw say the unit caused his RCD to trip even when it was switched off before unplugging? In that case it would have to be an N to E transient tripping the supply, and Clive's suggestion of a transient generated by the indicator and passed through the class Y cap may be more likely.

[@carlyonbay45]

Pulling out the notepad for the schematic ....that's the best part of these videos

[@coltronex]

I have the same unit at home,it is marked with a "BT" logo,works very well for testing kit with power line filtering missing,Colin.

[@maffysdad]

Hello Clive, we see you strip down these MOV and suppression circuits, along with your approval or disapproval of their safety aspect in relation to thermal fuses and neons vs LED's. You've torn down RCD's, fuses etc, shown USB ports and chargers at mains potential where they're able to power a light bulb, we know you're not too keen on neon test screwdrivers and you've educated us in that field, along with exterior LED lamps that don't have a earth wire, so all lots of protection stuff, I really like that. and I've taken a lot of notice of your videos and advice. I respect you're very qualified and have worked on many projects before you devoted your time to more family related issues. As a subscriber to your channel who finds your reverse engineering insightful and interesting, and more over because you actually explain and do the math at a level that even I understand (not that I can always keep up), and whilst I've only ever gone as far as adding MOV's and thermal fuses protection to four and six way extension sockets (back when it used to be cheaper to do this myself than buying a surge protection device made up). You seem to like the quality of this product yet felt it had some issues, so I'm curious, what would your own circuit design be to undertake the task of reducing interference and protecting devices from spikes, whilst showing a ground was active? And whilst our house has mains RCD fuses, I still tend to use a plug in RCD and a MOV/Thermal fuse extension for most things be then in the house or in the shed. I'd be very happy to have a in-line box if I can't fit your design into the extension socket housing, I struggled with the MOV's and thermal fuses, and I'm reading Chuckiele's comment about class X and class Y capacitors, so with all your experience, what would be your own personal ideal circuit. And please, I'd love LED's or neons to indicate what is protected and what isn't... I love lights!...

[@bigclivedotcom]

We don't get many huge electrical spikes here, so my own choice might be to rely on suppression capacitors to buffer the transients and take the top off them. That would mean an X2 either side of the common mode inductor and perhaps the class Y to earth too. Close to what you find in washing machine filters. If I was using MOVs the temptation would be to have them in their own earthed metal box and just leave them plugged in at a socket close to the distribution board.

[@theSam91]

I see a great many filter circuits like this built into the inverter welding machines I repair at work. Almost exactly the same but without the fuses. The MOV's are a common source of tripping the mains RCD, or if the user has powered their inverter welder with a noisy/unsuitable generator the MOV(s) usually goes kaboom - leaves a huge black skid mark and bits of MOV like shrapnel all over the place.

[@jamesvandamme7786]

The MOVs are marginally useful in a surge suppressor. If you are experiencing extremely bad recurring spikes, every cycle, the MOVs will soon die (I've seen power supplies that used them for voltage regulators, unsuccessfully). They will clip the odd lightning strike hitting the mains miles away, and possibly ward off evil spirits, but mostly they just sit there doing nothing until they die and go to hell. The cheap ones with no fuses may take you with them. The filters will do a lot to get rid of hash on the line. I have some filters with 2 or 3 LC stages.

[@akatizzle1585]

Bought an eBay clock kit after watching your video and everything went swimmingly, thanks Clive!

[@tin2001]

akaTizzle You did OK... I bought a bloody oscilloscope kit after that clock kit video.

[@BobVonBob]

I always get the weirdest commercials on Clive's channel, this time it was a 5 minute ad for a pillow website

[@maffysdad]

These were often sold by white goods companies as a method of reducing power surges when the white good item had a change of power state, so when a fridge/freezer cycles on/off etc. When the food chain Iceland used to sell fridges/freezers, this was what they always recommended be purchased at the same time. My mum brought two, one for each item... But this was back when you had to supply your own plug, before pre-moulded plugs came as standard...

[@Chipchase780]

At last, a cure for my insomnia !! Got as far as the thermal fuse and lost consciousness.

[@guitarstitch]

Very nice. Looks like something that if it failed, would be worth servicing to restoration again in lieu of binning it.

[@bigclivedotcom]

It's fully serviceable.

[@Chuckiele]

Well, a failing MOV can melt or burn the PCB or case before the thermal fuse pops but as long as that doesnt happen, it surely is very servicable.

[@anditrev9327]

Hi this unit was made by the same company that made the lightning surge arrester and explosive disconnect you looked at a while ago ( Bowthorpe EMP) their low voltage arm was called ASC, the star formation for the ZnO is both for cost and safety (150V parts are cheaper), but mainly if one of the discs fails (short circuit) then the second one in the chain would fail too, through over voltage, these would heat the thermal fuses and disconnect the unit, it sounds counter intuitive to deliberately fail a second component but for some fault states this is preferable e.g. high impedance earth loops. all their products were hand assembled, this looks to be about 2000 vintage. there were various forms having different levels of surge suppression / protection GDTs would be used where higher energies needed dissipating but they are slower to react that the ZnO discs.

[@bigclivedotcom]

That's quite a pedigree for a surge suppressor.

[@anditrev9327]

it was a very fun company to work for with a huge amount of experience in the black art of high voltage, EMP was the first to include surge suppression in plugs the PP1 you have the PP3

[@ribb4200]

Impressive. Designed to work. What we buy today saves cost by removing all the parts except the resistor and neon bulb, then inflating the ratings.

[@argoneum]

I've seen GDTs (gas discharge tubes) connected in series with MOVs "in the wild". I'd guess that they prevent the idle current from flowing, no idea what other benefits this arrangement would have. Decreasing MOV's wear maybe?

[@sivalley]

argoneum If you use a MOV in series with a GDT you can use a lower voltage MOV since any transient sufficient to spark the GDT is immediately desirable to be clamped. Problem is you need a higher current rated MOV to dissipate the same impulse power. It's safer and cheaper to ignore the GDT in this case and just use higher voltage rated MOVs. :) But yes, having a GDT inline would spare a MOV the burden of dealing with small inconsequential spikes and premature aging.

[@argoneum]

Thanks :)

[@anditrev9327]

GDTs are slower to respond but can handle higher energies

[@phils4634]

GDTs are very popular in telecomms. protection systems. Assivalley notes - they can be useful as "added protection" to MOVs, but be mindful that MOVs age, and will eventually fail in a conductive (or rather lower-voltage conducting) state.

[@anditrev9327]

EMP mainly made products for the power distribution sector they did have some telecoms products that retrofitted in exchanges but they used SCRs from what i remember

[@RealLuckless]

Today I learned that what I know as GFCI is RCD over there. And you guys seem to have them in way more places. Honestly tempted to wire my place in Canada in a more UK style with all GFCI, and each outlet on its own switch. Just seems sensible.

[@puckcat22679]

RealLuckless They don't have RCDs/GFCIs everywhere- they have what we'd call a main circuit breaker that is one, which protects the whole building. However, the problem there is that they probably end up with a lot more nuisance trips than we do, where we only have them on bathroom, kitchen, garage, and outdoor outlets. Keep in mind that the UK does a lot of things differently in part because they often use ring circuits, where a group of outlets are connected in a loop with each end of the loop connected at a high amperage circuit breaker. Current flows from either direction, meaning outlet style GFCIs like we have wouldn't work. This is also the reason plugs all have their own fuse- otherwise, you'd have a low amperage device protected by a 32 amp breaker.

[@RealLuckless]

puckcat22679 there are circuit level GFCI units rather than just the outlet ones. Plus I'm very tempted to move to a central distribution panel that then feeds to individual sub panels in each room. It is a bit more money, but I like the idea of walking across the room if I trip a breaker rather than having to go to the basement. Plus it means more flexibility any time I want to run upgrades without having to kill power to the whole house.

[@mitch19636]

Hello RealLuckless; I have a RCD on every circuit, including lights so some twit doesn't leave the light on whilst changing the 'globe', EXCEPT the air conditioner ccts.

[@WaltonPete]

I have a relatively new property, here in the UK, which has a main RCD for the consumer unit (fuse box), plus one for each circuit (kitchen, oven, outdoor lighting, sockets, alarm, lighting (which includes the single isolated shaver socket in each of the bathrooms)). As we have more electrical kitchen appliances than usual, due to disability, there's additionally a fused switch panel in the kitchen for each of the hardwired appliances.

[@Mark1024MAK]

RealLuckless We call earth leakage devices RCD's. Depending on the age of the installation and on how much money was spent on it, you can have the whole house protected by a single RCD, a split consumer unit with selected circuits only protected (e.g. just the socket outlets) with other circuits (lighting, shower) not protected, a consumer unit with some circuits protected by individual RCBO's(one per circuit, typically used for ring mains sockets) and other circuits not protected, and finally you can get socket S with a built-in RCD. So take your pick...

[@lostjohnny9000]

Those 4-gang surpressed extension cables from late 90s > often just contain a single 275V varistor across live and neutral. Having just one connected to the mains provides some transient protection for your entire house.

[@AlexLaw_Qld]

I think Huw is the Welsh spelling and pronounced "Tony" ;-)

[@junglepants7985]

Amateur here, but I didn't see any discharge resistors across those capacitors. Could it have been discharging to earth through the MOVs as that's the final connection remaining after the live and neutral pins escape their contacts?

[@anditrev9327]

the ZnO MOVs conduct enough to discharge the caps at low voltages

[@dustysparks]

In the US I think a design like this (with the voltage ratings adjusted of course) would still probably work fine as our circuit breakers aren't GFCI/RCD by default (which could be a good thing or a bad thing, I'll leave the debate for proper elecchickens). In the suppression circuits I've taken apart inside power strips, I usually see the thermal fuses intermixed with the MOV's and some even have a blob of solastic or thermal compound just to make sure there is good thermal contact. I also usually see the MOV's in a delta configuration (LN, LE, NE) and only 3 instead of the extra 4th one this unit has. Only the really expensive ones have the suppression chokes.

[@gregorythomas333]

"elecchickens" Bahahahaha :)

[@sivalley]

Gregory Thomas You have to thank our dear uncle bumblefuck (@AvE) for coining that term.

[@gregorythomas333]

I love the magic wall pixies too!

[@peterg.8245]

New construction depending on which version of NEC, national electric codes, your state or municipality have adopted, some automatically jump to the new codes and some have to be adopted by the legislature, require AFCI in all bedrooms and GFCI in all kitchen, bathroom, and exterior which includes garages. My last home of 2014 vintage in Oklahoma had all that... currently in a 1969 and feel just as safe. Although it was upgraded to 200A service with a new panel circa 1990. No asbestos and no aluminum wire in the construction it was to new for the former and too old for the latter, at least here in Oklahoma.

[@uK8cvPAq]

GFCI/RCD's are great...until you get nuisance tripping. Older homes are a pain for this sort of thing where the combined leakage currents add up, a few 100uA here and a few 100uA there from spiders, damp and debris across terminals etc along with leakage from appliances all crammed onto a single GCFI/RCD because the breaker panel and circuits are old. Having said that I'd still prefer to have them, they've saved my ass a few times.

[@lumpyfishgravy]

Thanks again for a stimulating video! I have heard of series GDT+MOV being used. Once the GDT incepts it will collapse like a neon so double digit volts. The combination has a sharper knee than MOV alone with much lower standing current, and might ameliorate MOV ageing. The idea of the star MOV arrangement is to split transient energy between two devices, thus you can get away with smaller devices overall. Those MOVs are big enough already! My only hunch about why it trips RCDs is to do with whether the N or L pin disconnects first could that do something? Pretty sure Huw is the Welsh spelling.

[@BritishAdam]

Huw is the Welsh equivelant of 'Hugh' - so you weren't far off with the pronunciation. Ace video as always, and far more educational than my college was!

[@ethanpoole3443]

Adam RDL Awesome, I learned something new and interesting today!

[@jonc4403]

So it's short for Hugh-Welsh then?

[@28YorkshireRose12]

This reminds me somewhat of an old "Ediswan" - "Suppressor Plug" we once had at home. We're going back to the mid/late '60s here. It must have been much simpler than this, but even so, it was still quite a bulky plug, or more like a standard footprint, but about thee times as thick/deep. Interestingly, it was on my parents' electric blanket, and was eventually tracked down as the cause of interference/noise on either, our radio (AM) or the old VHF telly (also AM) - I don't really remember which, but once the suppressor was 'oiked out, we had no more trouble. Weird or what?

[@shurdi3]

The common mode choke makes a lot of sense as the culprit, since if you unplug it at the wrong time when the magnetic field collapses it'd probably make quite the spike

[@shurdi3]

Also those suppression chokes would probably be super easy to recycle as Joule Thieves

[@nikf3188]

I've got a BT one of these with a plug socket on, they were used by them on PBX power plugs in 1800 & frozen to death!

[@rambo1152]

It looks like the sort of thing BT liked to fit to their office telephone systems, although the load usually plugged into the front rather than being hard-wired.

[@anditrev9327]

EMP made many versions all based around similar technology

[@PhilXavierSierraJones]

I remember having a controller for heated mattress which tripped circuit breaker if you leave the connector that goes into the mattress unplugged before plugging it in. Not sure why it did that, but it caused quite a lot of fuss here after every cleaning.

[@Totogita]

I just dismantled a coffee maker for parts and the circuit look similar to this , there was a relay and a timing circuit

[@LMacNeill]

Forgive my ignorance, but what does RCD stand for? I assume it has the same function as GFI does here in America, it's just called something different in the U.K.? (FYI: GFI stands for Ground Fault Interrupt, sometimes referred to as GFCI or Ground Fault Circuit Interrupt).

[@bigclivedotcom]

RCD stands for Residual Current Device.

[@nrg-5003]

Yep their the same but with different names.

[@mikecowen6507]

Where in the circuit were the GDTs located? Also, what was the manufacturing date on the components? Easy to estimate the age of the unit that way.

[@finndriver1063]

Would this stop one of those powerline ethernet adapter things that put the LAN through the house copper from working? Not saying it would be a useful application, just wondering.

[@truckerallikatuk]

Maybe. It could stop it, or limit bandwidth at least. It'd be trying to fight the signals to an extent.

[@PileOfEmptyTapes]

Depends. I'd expect it to interfere with the 3-wire "1200 Mbit/s" varieties, but the slower 2-wire ones should be less bothered (though differential filter capacitance still is quite high). However, I'd rather put the filter on a noisy load, as ironically this powerline ethernet stuff is super duper sensitive to switch-mode power supply crap (one reason why these things are supposed to be used directly at the wall outlet). The cleaner the mains, the better the throughput and the less transmit power is needed, in turn reducing radiated interference for everyone around. (Once that is sorted out, the only thing that can go wrong is having units on different phases, in which case a dedicated bridge has to be installed by an electrician.) BTW, it is rumored that powerline ethernet devices have a habit of EMI degrading over time, ultimately failing to meet regulations, possibly as a result of filter components aging. I would only ever consider getting the best-quality ones, which around here would mean Devolo.

[@superdau]

Any date codes on the components? The PCB has 9644 on it which could mean 44th week of 1996.

[@anditrev9327]

that would be correct but as these were made to order i could be some time after that they were assembled and sold

[@dr666demento]

Judging from the cracking and yellowing plastic, I say it's older than '96 - possibly '86.

[@AntonyTCurtis]

Could be simply too much bromine in the ABS made it age faster even in the absence of light. Given the overkill in its construction, I wouldn't be surprised if they went overkill on the fire retardant.

[@barrybritcher]

I thought the QA / QC sticker said 94 I'll watch it again now

[@barrybritcher]

Nope is says 15 oops

[@towtypao]

The xcap after the cmc and the 2 ycaps have no bleeder resistors, those may have looped a path through the middle mov with a series voltage enough to breakdown the L-N mov's and trip the load rcd.

[@RavenLuni]

Ah so thats what parallel inductors are for - I recently harvested a couple of chips from an old router that according to their datasheets consist of multiple transformer and suppressor arrangements in series. I'm guessing thats to completely separate it from all external signal sources? (they were being used to terminate the sockets)

[@GreatJoe]

I'm guessing (GUESSING) the GDTs were for 120V use, and instead of changing the form factor for 240V-compatible GDTs they sized up the MOVs to compensate.

[@joinedupjon]

random teardown suggestion... just browsing aldis and they're still selling a CFL lightbulb. These are pretty obsolete technology now and presumably going to get phased out fairly soon - but notably the 'ballast' unit below the tube on it was really small in comparison to the few year old units I've still got around. I guess CFL technology must be in it's ultimate form cos I can't see anyone wanting to put much money into further development. Might be interesting to see how they got the balast size down and whether it contains a ferrite suitable for a joule thief transformer.

[@ethanpoole3443]

joinedupjon Depending upon the firing voltage requirements of the fluorescent tube versus local one voltage, I have seen ballasts (even in the past) that were nothing more than a capacitive dropper combined with a small TO-92 triac to do the initial striking -- essentially nearly identical to that found in many cheap LED bulbs today.

[@joinedupjon]

Hi Ethan Poole... even if it's electrically boring I guess the thermal design improved over the 15 or so glory years of consumer CFLs

[@ethanpoole3443]

joinedupjon If a capacitive dropper ballast is used then there is practically no heat in the ballast as the film capacitors typically used have extremely low ESR (equivalent series resistance) at 50/60 Hz AC so there is only heat production if a ballast resistor was also used to improve the power factor, in which case the heat produced will be determined almost entirely by that resistor (they usually use power resistors rated at 5W, so dissipation will be on the order of a few watts maximum, which is not too hard to dissipate).

[@d2factotum]

It didn't look like the thermal fuses went high enough to cover all the varistors, what would have happened if the topmost one had blown?

[@4DRC_]

I have an interesting halogen/CFL combo I found at the discount store that I want to send to you for a teardown. How do I go about doing that?

[@abyssalreclass]

I had a surge protector that would trip a GFCI whenever it was plugged in. I imagine the earth leakage you were talking about was the cause. Either way, I tossed it and bought a new one.

[@TheMushtyroo]

Date of manufacture printed on the inside of the case - Circa 1995?

[@kenaston4220]

My understanding of ELCBs, is that they look for a current that is going out on the Live that is not matched by exactly the same current coming back on the Neutral ( no current flowing to earth) So I wonder if the live current passing through the 4.7n capacitor, to earth, is enough to cause the imbalance?

[@bigclivedotcom]

The current through a 4.7nF capacitor would be tiny. Measured in microamps.

[@TSGZeroHundred]

You should do something on one of those water powered clocks, I'm sure you could find something online

[@bigclivedotcom]

They're usually just a battery based on metal strips with the water acting as the electrolyte the metals eat away over time.

[@123mikeyd321]

Any name on it? It looks from the outside identical to ones we used to use on our servers 20+ years ago branded Roxburgh. That was in the day when servers were PC towers. I'll have to see if I can dig one out to compare.

[@anditrev9327]

at 8 seconds the black label says B.EMP which is Bowthorp EMP Brighton UK

[@bren106]

Huw knows how to pronounce the name Huw?

[@Ian-Steele]

bren106 Huw is a Welsh variation of Hugh. The BBC newscaster Huw Edwards for example, or further back in time the famous broadcaster Huw Wheldon.

[@bdf2718]

It's like Hugh but with a distinct "wuh" at the end. Only "wuh" without the "uh." It's Welsh. Those guys are weird. :)

[@lightningslim]

In Welsh, h is h, u, unfortunately is English y and w is pronounced oo. So you end up with a pronunciation of "Hyew", which, when you think about it, is just as daft as "Hugh" being pronounced "Hyew!" 😁

[@Thirdbase9]

Huw's on First?

[@Bubu567]

@@bdf2718 Huw what mate?

[@RonJohn63]

I've never seen anything like this in the US. What equipment requires interference to be suppressed?

[@bigclivedotcom]

Usually audio equipment. But anything you want protected from electrical spikes that could gradually cause a power supply to fail.

[@Roy_Tellason]

@@bigclivedotcom Gradually? A lot of the failures that I've seen have been blown diodes, nothing gradual about that. :-) What equipment? An awful lot. I've done a fair amount of scrapping stuff out, and have a fair pile of those common mode chokes, X and Y rated capacitors, and similar parts as well as complete line filters, waiting for me to find a use for them.

[@whitehoose]

It looks very much like the mains filter used by BT, couple of options available one was for rural units that had LV overhead mains feeds and used gas discharge in both mains and phone line to "protect" against lightening strikes!!. Along with a locally provided earth spike to dump to. Became necessary when old relay and switch kit (which would work with anything) gave way to the first generation of new fangled processor controlled systems (which were to say the least - particular where they were plugged in). Mains power was an absolute f*&*?*$$ nightmare, both in City centres and out in the sticks so mains conditioning units, filters etc were bunged in everywhere - I still have one of those filters in my office ... just in case.

[@billyproctor9714]

Thanks for the break-down Clive. I think I see 4 Varistors, how will that effect the output? Billy in Canada

[@bigclivedotcom]

They should only conduct during spikes and will not affect the output.

[@JamesKruseArtist]

I hope you’re is around when the aliens land, you can then tell us what they have and we might actually understand it!

[@AlfaGTA156]

James Kruse indeed. No doubt he will reverse engineer a warp drive internal accelerator👍

[@JamesKruseArtist]

JRP Romeo156GTA I mean, he explains the complicated with the understanding of an old friend, if this guy had been my teacher, I would have actually learned something way back then. I have a new respect for engineers that had to grow up in areas where 220 is the norm, in the US, our little 110 is not that scary, I can’t imagine having to learn on 220.

[@gary851]

Hey Clive. Why is front usb port in my PC live? it is putting like 24V - from "feel" test when i hold tip of us cable and hold a heater.

[@bigclivedotcom]

Does it happen with other appliances? The heater may be ungrounded.

[@BEdmonson85]

Clive, can you explain exactly what " common-mode" currents are? This one concept has always somewhat confused me.

[@bigclivedotcom]

Common to both the live and neutral but in phase as opposed to the actual live and neutral. Basically electrical noise trying to find a way to ground via the two wires.

[@ethanpoole3443]

As Clive mentions, if the signal is carried by both Live and Neutral and both are carrying the exact same signal, identical even in phasing, then that is common mode (it is common to both conductors). If they were to carry the same signal but in opposing phases then it would be differential mode. In a common mode choke the two sets of coils are wound as mirror images of one another such that when each sees an equal and in-phase interference signal they each produce a magnetic flux of opposing polarity which means they effectively cancel each other out thus cancelling the interference. In a differential mode choke the two sets of coils are wound identically to one another so only interference that is of opposing phases gets cancelled out by the choke. Bonus fact, a GFCI/RCD will typically consist of a common mode wound choke with a third sensing coil added to it to detect the imbalance between live/hot and neutral. As long as each conductor is passing identical current they will magnetically cancel out and no current is produced in the sensing coil. But the moment there is a discrepancy due to leakage to earth in one of those current legs the two common mode coils will have different intensities in their magnetic fields and no longer fully cancel out one another, inducing a current in the sensing coil and if that current exceeds a certain limit then the GFCI/RCD will trip, opening the circuit and rendering it safe.

[@nozyspy4967]

What exactly is the purpose of an interference suppression plugin laymans terms?

[@AintBigAintClever]

Dammit, I've got a few different variants of these knocking about, I've got schematics dated June 2016 but I've not bothered videoing them. The MOV star in these is even stranger than yours. The PM2A and PM4B/10 (both made by Bowthorpe for BT) both have a 130V MOV to Live with 150V for the others.

[@bigclivedotcom]

The more schematics and videos on KZbin the better.

[@phonotical]

Would it work better with the discharge tubes installed? Any way you could look at a baby heartbeat monitor?

[@anditrev9327]

nope too slow for the application

[@uK8cvPAq]

I think discharge tubes are meant for last resort one shot protection, I know they don't last that long anyway.

[@simonhopkins3867]

fascinating. Thanks Mr.

[@steve64464]

Is there actually much value in such suppressors or is it like the Chinese power saver boxes? and how would one go about detecting if they had interference on their power lines? is that a oscilloscope job?

[@44R0Ndin]

These kind of noise suppressors do have a use, provided you have a piece of noisy equipment in your house. Since universal motors are quite common in things like vacuum cleaners, and they're quite electrically noisy (not to mention the sound), if you have your computer or TV power cable plugged in to one of these, and then the wall, then your vacuum cleaner won't induce noise on the audio line of your computer or TV. At least, that's the theory, there's crap noise suppressors out there that don't actually do anything beneficial. Generally if it's too good of a price to be believable, it's not going to work.

[@brocktechnology]

In my experience most people are completely unaware of any interference in their homes. The first sign for most people is the neighborhood ham radio operator showing up on their doorstep hoping he can take a look around for the noise signal he's trying to dig out of his radios.

[@steve64464]

See i have this pc that randomly crashes and ive been through a lot of diagnostics etc but i haven't been able to rule this out as a possibility.

[@anditrev9327]

yep, best way is by a CT or resistive divider with the 'scope trigger above the mains level, you are looking for micro second events

[@steve64464]

Yeah i don't think i want to check a 240v line it may hurt :-D

[@TheSaabClinicUK]

Ive got 3 that look exactly the same as that. Apart from they have a RS Components mark. I would say ive had them at least 15yrs.

[@anditrev9327]

the main customer was RS it was rebadged for them

[@pirateman1966]

Why don't they use spark gaps instead of MOVs?

[@two_tier_gary_rumain]

Does the standard British power socket come with an on/off switch? I know US ones don't but every Australian power socket has a switch.

[@jas88cam]

Gary Rumain Yes, they do. Probably where Australia gets it from too.

[@w41ty]

Optional, New builds in UK yes switch on sockets. On older houses not unless replaced with new switch sockets . But in Ireland they use same socket but don't bother with the switches but socket plates with switches are available.

[@two_tier_gary_rumain]

Unlikely. Australia has had switches on the power sockets since, at least, the 50s.

[@two_tier_gary_rumain]

So it's a recent thing. Was it a law?

[@jas88cam]

Government standard published back in 1944, for the UK - before that, some outlets were switched, some weren’t, and there were a few different sockets in use. That was also the report which introduced our “ring main” wiring and mandated fuses in plugs.

[@zx8401ztv]

It looks like a "no corners cut" decent device, nice to see a decent job :-D. I would reconfigure the output vdr's and use it.

[@AttilaAsztalos]

Nonsense! The upper-left corner has clearly been cut at 1:22...! ;)

[@anditrev9327]

think someone tried opening with a spudger before noticing the screw holes are plugged ;)

[@ahemadzaqtoot9172]

Love your videos

[@thebeststooge]

If only companies made these as well today as that looks like it was built like a tank.

[@mark-]

can you review PC computer power supplies please

[@geofflotton5292]

Neon to show when the fuse has blown.

[@Ian-Steele]

Never heard of Huw Edwards of the BBC !

[@robfenwitch7403]

Journalist and newsreader

[@choppertimberland139]

Big Black Cock lol

[@MaverickandStuff]

My computer is sending high frequency into my wall outlet causing interference with my stereo. Would one of these help with my problem?

[@bigclivedotcom]

It might, but if your computer is connected to your stereo then consider an audio isolation transformer.

[@ethanpoole3443]

Look into the TrippLite IsoBar series outlet strips as they have very effective surge and noise filtering. I use them on most items of real value, including computers, TVs, audio gear, and test gear, and they are very good at protecting equipment, including UPS's, from damaging surges (such as a mains transformer shorting out) as well as from RFI noise. Every bank of outlets in the strip is separately filtered from its neighbor. But a more common problem with hum and noise stems from unintended ground loops and if that is your issue then an audio isolation transformer, as suggested by Clive, will also prove necessary to help break the ground loop. If you feed your computer into your audio amplifier then it is not unusual to have noise coupled onto the chassis ground by the noise suppression capacities in the power supply, and that can also be helped with an audio isolation transformer.

[@carpespasm]

I wish to see the gadget mountain.

[@TeChM4NuAloJuNkiE]

Please please big Clive PLEASE can you put to the description from every video a link, example a rar file with txt files with the name,model, some photos of the item you show, the schematic(if you have made) and everything else you print from prints you show us to the videos ???? PLEASEEEEEEEE

[@Anvilshock]

Aren't you quite the demanding one …

[@brianevans1946]

Great video.. Where do you buy those handy screwdrivers?

[@-yeme-]

Poundland. Seriously, theyre a quid and theyre really good, the tips are properly hardened and dont deform easily.

[@michaeltempsch5282]

And if one's not in Poundland-land, they're on eBay, AliExpress and many other of the Chinese online stores. Usually findable by searching for 8 in 1 or 9 in 1 screwdriver

[@brianevans1946]

Thanks

[@Cadwaladr]

I just hope Huw doesn't play baseball, because that could cause some confusion.

[@kb1gni]

I was wondering if I was the only one to catch the Abbot and Costello reference, intentional or not as it may have been.

[@ToumalRakesh]

I wanna dive into the gadget mountain.

[@maicod]

I bet your eyes would be pinned by the legs of LEDs :)

[@sdavies45]

I was hoping you would plug that in to see it trip the RCD.......

[@twocvbloke]

I'd guess that it's not meant to be unplugged or switched off, but left in place for something that runs 24/7, like a telephone PABX or CCTV system, that way it wouldn't be tripping RCDs unless there was a genuine fault... :)

[@anditrev9327]

spot on

[@warrobots5877]

What do you do for a living

[@bigclivedotcom]

Freelance electrician.

[@dunc1958]

with you being a Scot I'd have thought Huw would be pronounced Shug

[@dogwalker666]

i have an identical unit except it has a BT logo on it came of an old PBX (Private Business Exchange) i removed

[@johndii2194]

Class Y and X? I had to go look that up. Stop making me want to learn more.

[@maffysdad]

I know, Clive does this to us every time!... I've just felt the need to go dig through boxes in the attic hoping to find a old one I think I have, no, I know I have it, I just can't find it!... I might as well just tidy my attic now! lol!...

[@Ramog1000]

now he also makes you tidy up things xD

[@Chuckiele]

Its quite easy: class X goes between live and neutral and must withstand 250V AC while having a large capacity, class Y goes from live to earth and neutral to earth (or from the high voltage side to the low voltage side of a transformer) and they must never fail short circuit while having a small capacity. They are both made for interference and noise supression.

[@TC-tn9tb]

look a the thick copper wires a well made quality item.

[@mjouwbuis]

Old, but likely post-1993 given the EC mark.

[@alidee5448]

"Made in B. EMP" British Empire?!?!

[@stephencresswell4760]

But what was wrong with it in the first place? I need closure. 😩

[@maicod]

just give me your keys and I will gladly close you off :)

[@glenngoodale1709]

those plugs look like what they used in the cave man days

[@daverhodes382]

KKK Grand Dragon Adam Racewarski Are you unwell?

[@bdf2718]

The only bit of shoddy design is the 3-pin choccy block. Which means line, neutral and earth wires are all the same length. Which means enough force on the cable (say from tripping over it) gives you Russian Roulette odds of it failing safely compared to a standard BS1363 plug. Unlikely for it to fail in that way, but it's not impossible.

[@twocvbloke]

Of course, you could just cut the Earth wire so it's longer than the others..... :)

[@anditrev9327]

these were sold to retro fit suppression and filtering to a device hence the "choc bloc" that is the same mechanism as is used in uk mains plugs the installer should have a longer earth cut

[@joshman9757]

I am trying hard to understand

[@adventcontrols]

MOVs are too slow I would have thought

[@mikecawood]

Huw and Hugh are both pronounced the same.

[@richardkaz2336]

I have often wounded the effectiveness of the high frequency cap and mov components tying the Neutral to Earth when the supply is connected to an MEN supply system. I can see benefits if it's connected to a fully floating supply system. Any comments???

[@raymondmucklow3793]

I bid everyone a good day.

[@davidclelland1152]

Hi hehe can you power a 220 volt (gu10) with 12 volt T full power , and how to make the mod t

[@bigclivedotcom]

For some with three LEDs in series you could just use a resistor to drive the LEDs directly.

[@AndyHullMcPenguin]

Just in case anybody cares... Huw - en.wikipedia.org/wiki/Huw Pronounced the same as Hugh.. and the reason I knew that... a mate of mine in my youth was called Huw (he was Welsh, CB handle was Welsh Dragon as I recall)..

[@hommie789]

Why not try to replicate the problem and see what you find? You didn't plug it in to the hobbie to see how it compares to others either just a open and look approach.

[@bigclivedotcom]

The Hopi would not have shown anything. To test it would require quite complex testing equipment to generate transients and measure the effectiveness of the unit in suppressing them.

[@IanScottJohnston]

Yup, RS still sell them. I have one and opened it up and it's the same as Clive's. Last time I used it, it indeed tripped my RCD. uk.rs-online.com/web/p/surge-suppressor-units/0239567/

[@anditrev9327]

glad to see tycho still sell them after they bought out EMP

[@longrunner258]

According to Zero Surge (makers of heavy-duty 'Power Quality' filters), attempting to clamp "common-mode" surges is both dangerous and unnecessary anyway: zerosurge.com/normal-mode-v-common-mode/ (Sure, they're a commercial manufacturer too; but I can't see any fault in the arguments given.) It also continues to disturb me how many MOVs are *still* installed without thermal fuses, *and* often in plastic housings to add injury to insult. (This is my main concern with the current version of the Allocacoc PowerCubes, by the way; if you want to make them safe, either add in a thermal fuse, or cut the MOV out altogether.)

[@legobuildingsrewiew7538]

Hey whats up with photonicinduction?

[@chrisrogers2848]

First comment! Yay! Love your channel Big Clive - inspiring me to become better at electronics.

[@l3p3]

First annoyance, I would say.

[@Mezgrman]

They did say something nice at least. :)

[@muesli4597]

Shirley thats a choke

[@robfenwitch7403]

I'll bite... Of course it is and stop calling me Shirley...

[@Elfnetdesigns]

Gadget Mountain...