Surge Protection Devices - Part 2

[@mahmoodmirza3301]

I also loved the demonstration of the SPD's function upon it's exposure to increasingly higher voltage and it's dramatically decreasing Resistance. Thank you again

[@HandyKindaGuyUK]

John...... we just want to see you. Blow it up! Never did thankyou for getting me through two of my exams. Honestly couldn't have done it without your videos, thankyou so much

[@gassanali8667]

What are those videos?

[@eepower]

Absolutely Amazing! thank you John for sharing the knowledge. I appreciate your time making these great videos.

[@sumitkumar-hp5mm]

Very informative and great explanation sir.....firstly telling theory and then proving that theory with practical...just awesome...I will give presentation in my class over this topic

[@jamesmauer7398]

Nice demonstration of the MOV operation!

[@gjergjkastro9404]

Thank you John for this tutorial. Keep up the good work!

[@SoYFooD2]

for information in dutch systems the SPD (OSB) needs to be in a location withing 40CM of the incoming (main) ground (PE). also a type 2 only need a fuse if it can pull more than 125A if it breaks, if do u use a 63A fuse. a type1 can take 250A and need a 125A fuse if the installation can handle more than 250A and last but not least a type 1+2 needs to follow the type 2 specs.

[@uvtube2008]

Both parts are highly educative and practically useful! Thanks!

[@mikeZL3XD7029]

JW, Thank you very much for this series of videos, I've never seen MOV's explained so thoroughly before.

[@ahmedelectricianofiraq5550]

Great video and as usual excellent demonstration. Keep on 👍

[@kcuhc84]

Very informative, I understand that the multimeter has MOVs in as well.

[@tonyfrewin4822]

Brilliant explanation and demo. Haven’t seen a Mega like that since about 1980 when I was an apprentice. The electricians would love to give the apprentice a shock with the handle spinning and max rpm. 😂.

[@Rob-ln7dd]

Yep got zapped myself in 1980... I went to the factory for a 2 week induction after finishing O levels before starting first year training at the local tech college in September. As i was one of the youngest in my year I was only 15 years old for the first week...loved it... Apart from the megger zap. It was a boiler and radiator manufacturer in Yorkshire, the electrical workshop was a dark place (ironically) and Dick the oldest sparky held challenges to see who could hold the Megger for the longest time and get the highest reading.... He could of course... ElfNSafety didn't exist...hahaha

[@mahmoodmirza3301]

'Novel Idea' of installing a Single SPD across the 'Neutal' and 'Live/Phase' wires when one has no provision of an effective 'Ground/ Earth'. Excellent idea. I liked it.

[@RetiredandLivingthedream]

Very good thanks always wondered how they work.

[@arRazmanMyDIY]

Amazing demonstaration John. Now I can understand how that small stuff working........very easy to understand....

[@BlueSky-cy5nw]

Great demo of the surge protector working. First time seen someone do that. 👍

[@Tomee62538]

Thank you for a brilliant video, great teaching skills.

[@EyadAbsi]

As always, your videos are very informative, thank you John Ward for your great job.

[@troytaylor1913]

When those MOV's go they really go up in smoke if they are unfused. I use to work in a packing factory and about once every three months a MOV in one of the bagging machines would burn up and stink up the whole factory. My boss was dumb and couldn't understand why I wanted to replace components that would burn up on occasion. For me replacing them was very important because the circuit boards the MOV's protected in those machines cost thousands.

[@Harsha99924]

Very nice video. Very very useful. First time I know how to check MOV at home. 👍

[@syedirfanahmad9626]

Very useful intro and inside details. It helped a lot understanding how this device works.

[@boolve]

Thanks for that. Not just theory but and in practice. Valuable info

[@markg7702]

Thanks for another great video JW

[@vwthings]

John, write this down in your diary. 1st March 9pm on River Gibbs FM (easily heard via internet). You get a mention after first track and appear in the intro! - Hello, I'm JW....

[@EFIELDIQ]

Hi Jackbox how are you

[@luke-bookbear]

This video was extremely helpful. Trying to protect some expensive equipment I have ere, I got the lucky the other day when lighting hit. No more risks (or much, much less risk) this time around Thanks!

[@johnyearsley7970]

Thank you John Brilliant from John.

[@AngusAbbott-qf8xm]

Great explanation of SPD’s and their role 👍🏼

[@bensonchukwu813]

Highly informative lecture. Surge protector demystified

[@zazugee]

nice demonstration, i always wanted an insulation tester but never managed to buy one yet

[@Rcbeacon]

It would be nice to see the MOV that's hiding in the resin. Being a cheap unit I wonder if it really is a good sized MOV or just a well hidden tiny one.

[@troytaylor1913]

I found that I can buy these Chinese MOV's about ten cents per part no matter what the value or size. If a factory buys reels in volume the price goes down even lower. Where I worked they bought components like these for 2 cents. It makes me wonder why a multimeter with a MOV costs three times as much as a multimeter without.

[@RoccoWalton2005]

Thanks for the detailed information!

[@dimitriderop2543]

I have at home a TT installation, and 3 x 230 Vac plus neutral. A bit more troublesome to install SPDs. The video didn't explain the differences between (Type 1,) Type 2, Type 3 SPDs. Also, some SPDs only contain MOVs, but many also GDTs (and TVS diodes).

[@tinaluke5124]

I seen plenty of MOVs blow up and cause fire and serious damage to the wiring, at least these ones are encased in resin. Earth leakage also trips during lightening storms which protected me over the years, now they are making surge protection mandatory. Most sensitive appliances already have surge protection built in.

[@marcioportella2785]

Thanks !!!! Your demonstration is great!!!! Congratulations for your great work :)

[@norbertvarga8621]

Great stuff as always!

[@ehsanbalouch4771]

Beautifully investigated.

[@semirauthsala6001]

wow. best explanation video I ever watched. keep up the good work.

[@valeriubuznea4073]

Great demo !

[@ashmanelectricalservices4318]

The real issue for me is, realistically how likely is it that the end user will frequently monitor the functionality of the these devices. CU's are generally hidden away somewhere underneath a staircase or at the back of a storage cupboard and only ever looked at when there is a problem. If the SPD fails and requires replacing, everything in the installation will continue to work with the end user unaware of the failure.

[@jwflame]

That is part of an existing problem, which is that most people consider electrical installations to be magic and just work for ever with no maintenance or repairs needed.

[@Mark1024MAK]

Ashman Electrical Services - even less likely that the SPD(s) will be maintained once the end user discovers that it will cost them money for no immediately visible benefit...

[@echenduconfidence4998]

thanks for the explanation, i thought when there's a higher voltage it will discharge it via the earth part

[@sahansam]

Very good and vital lesson. Thank you

[@atomicdmt8763]

excellent. well done! very helpful

[@sciencetestsubject]

I had a surge protector installed in my consumer unit, but the inserts are 2 different types. The insert between line and earth has a model number with a V inside it, but the insert between neutral and earth has a T in its model number. It's also labelled N/PE on the case.

[@muzikman2008]

Ones a MOV Varistor, and the other is a gas discharge tube..I think..

[@TRS-Tech]

It has always been the case that new devices like these will have a massive profit margin as users have no idea that it is a few simple component that costs pence when purchased in bulk, it is the same with the gas discharge tube you find on the more expensive devices. One of the features these have that wasn't mentioned is that the fault indicator arm when operated will protrude from the bottom of the module. If you have holders with the small microswitch in the base this is pushed in by the pin at bottom of the module. This will then operate some form of warning device so serves as a very basic fault warning feature. When you consider the current that will flow during an overvoltage condition I can see an issue arising. If the device is inline with a simple MCB this would operate during an overvoltage pulse and would very likely be enough to trip the magnetic plunger fast disconnect in the MCB. This suggests that a higher rating MCB should be used but this would increase the chances of an overheating or fire. I have used MOV's and GDT's in my own installation but used an MCB designed for high inductance loads. This will minimise the chances of a transient causing the MCB to open and depriving you of all future protection. It is therefore vital to have a method of monitoring failure of the module and tripping of its protective device. Save yourself a lot of money and purchase some high grade MOV's, GDT's and incorporate a spark gap if you can. I have also seen some SPD devices using thyristors to clamp large surges. Using thermal glue bond some 80 of 100 degree centigrade thermal fuses and wire them in series with the MOV;s. As varistors fail they will slowly heat up so thermal protection is vital. I also incorporated a cartridge ceramic fuse (slow blow) and a continuous operation mains relay. Wire this to the output side so if the MCB trips, thermal fuse opens or fuse fails the contacts will open. The relay contacts are connected so they interrupt connection to a mains rated buzzer and warning lap. A neon with current limiting resistor can be used to show that the supply is present. Place all these components in a sturdy metal project box (don't forget to bond the PE to the box) and if you have used the correct components and wired the box correctly you will have a device that does everything a type 1, 2 and 3 SPD can do at a fraction of the price......... P.S. Don't forget to isolate your SPD when performing any insulation testing. I hope this will help those of us who know what we are doing and can construct a device like this ourselves. Do not attempt making an SDP unless you know what you are doing ! One other question I had.... I remember watching a study by one of the universities that proved the majority of the energy flow was in the upward strike and the downward strike only when attracted by the potential difference in the ground served to ionise the air and allow the energy to escape upwards. In my experience with data and comms I have seen far more damage done to buried cables than overhead catenary cable runs. I am 99% sure that the study I watched proved that underground cables were at a higher risk than overhead ones. If this is not the case these days I can only assume it is due to underground cables being run in ducts or directly buried cables being SWA. Overhead run power lines and telecom services normally just have a stringer for support and would get no benefit from the shielding effect of SWA cable. Has anyone seen any later studies of lightning behaviour ? The study I watched was done in the early 90's. Cheers all. Stuart

[@jwflame]

MCBs are too slow to react to overvoltage transients - typical duration of microseconds, compared to milliseconds to trip an MCB.

[@TRS-Tech]

@@jwflame I was considering the fault current that flows when the MOV clamps as opposed to high voltage spikes affecting an MCB. It may be possibly damage an RCD with its electronics but I expect they install a MOV on the RCD to protect against this. I can foresee problems with the MOV's leaking as they wear out and someone has made the mistake of installing the SPD on a MCB that is protected by an RCD. Could be a visit to false trip RCD hell if you are not aware. I would be interested to know if anyone has seen thyristors or heavy duty zener type protection on an appliance or an SPD. Thanks for the reply John.

[@afzalyousufi4932]

Wonderful, not seen any explanation like this.

[@bernardcharlesworth9860]

A wylex SPD in a domestic consumer unit is rated at 125amps so the SPD is protected by fire by the 100 amp cutout fuse.The cable to the unit could be 2.5mm so I would connect via a 16amp breaker not 32amp as suggested by this gentleman .I am always open to further insight into these resently new devices.

[@angelanuccio2167]

I loved your input , could you tell me how i can run L and N into one hole and then L and N carry on , am i supposed to run 2 wires into each hole like hes been drawing ?

[@bernardcharlesworth9860]

@@angelanuccio2167 no it's just a three wire device .line from breaker.neutral from buss bar and earth to earth bar. On overvoltage it dumps power to earth.

[@trevorlewis2758]

GREAT DEMO !

[@salmanqaiser6918]

does it protect by dissipating all surge energy into heat or major portion goes to the earth? Thanks in advance

[@___Chris___]

Thanks for the explanations. If I understand you correctly, the SPD is only side-wired to the main power flow of the individual conductors (which would explain why for each conductor there is just one connection coming in, but not coming out again, apart from short-circuiting to one of the other conductors, in case of a voltage surge). This also means that the main lines are not interrupted, so if e.g. a lightning strike feed its energy into a phase or neutral conductor of the main power line, what prevents the current from reaching connected devices? Is it only about the path of least resistance?

[@Funnyanimasl]

Super work

[@giovanninongbri2250]

So for my solar system having an open circuit Voltage (Voc) of 38Volts. What should be the size or rating of DC SPD?

[@madintheheid]

Top stuff, JW, thank you.

[@nrgia]

Wonderful explanation. Thank you.

[@marioserafimov7254]

This was really helpful mate. Thank you.

[@henrytwigger2245]

So when it gets too hot and fails, it disconnects it's self, but doesn't disconnect the apparatus that it's supposed to be protecting.

[@sus-zg3mq]

Just Amazing sir...Salute to you

[@angelanuccio2167]

So to put that inbetween solar panels and inverter your supposed to run the L and N in and run another set in the same hole coming out to carry on , really makes no sense , id like to see you wire one into a system instead of drawing lines and disecting the device . or does this just run off the side of the breaker and is supposed to just capture said surge?

[@plasmatorque4318]

As per your demonstration each surge protective module seems to have a clamping voltage limit of about 600 V DC. So when installed, as both devices are in series with the Live and Neutral lines, wound't it give a surge protection above 1200V (or 850 V AC) or so between the lines? isn't it to high?

[@bigwave_dave8468]

Great explanation John. I was trying to understand the failure modes after we some kind of significant surge resulting in a neighborhood power outage for 24hours (I assume the power company swapped a transformer). I had a power strip surge protector with two MOV devices [L, N]. When the surge occurred, it tripped the breaker. Upon resetting the breaker, the surge protector burned, indicating a direct short. I didn't know the MOV would fail shorted but it did it's job. We had 3 circuits trip, all of which had MOV surge protectors. Two of which failed permanently (or rather, "succeeded" by dying :-). As a result, I'm looking at how best to protect the electric panel at the source. Is there any type of surge protector/breaker that can reset automatically after a single event upset?

[@ColinDH12345]

Great video as usual, very educational. I would like to know just how much of a real issue this is for the general public, what frequency of surges actually happen in rural and urban areas for example. Or is this an opportunity for the manufacturers to cash in... call me a cynic :-) Also, given the large amount of heat produced (enough to melt solder), what about units next to these (MCB/RCBO, etc.? Should a space be left between the Surge Protector and MCB/RCBOs?

[@Mark1024MAK]

Where I live, in my home, I’ve not known any electrical or electronic device that has failed because of a surge. However, the problem is that you are not likely to know if/when a surge has occurred. And when an electrical or electronic device does fail, you then don’t know why. All I know, is that when any of my electrical or electronic devices have gone faulty, nothing else has failed at the same time. Hence, if there has been a surge, it must have been rather selective!!! Where I work however, some outside effect (lightening is suspected, although not a direct strike, or possibility electromagnetic induction from something else) has caused surge arrestor protection modules to go low impedance, which did protect the communication equipment (linked by miles of long distance external telephone type cables) , but caused a loss of communication until we replaced or disconnected the failed surge protection units. The older design of communication surge protection units that we used to use, were constructed using two RF chokes (in series to the equipment), two 100mA fast acting fuses (also in series), back/back 12V Zener diodes across the lines, and a ‘three terminal’ gas discharge device (middle terminal to earth, other two terminals to line A and line B). In these, we mostly just had to replace the fuses after lightening storms.

[@milos_radovanovic]

I'm not the expert on SPDs, but from what I understand, this was wrong at least on the "low" impedance part of the explanation 5:51. Overcurrent protection is meant for handling failure modes. MOV normally doesn't act as a short circuit during a surge, it is rather akin to zener diode and shortness only has to do with energy handling capacity. As I understand them most SPDs contain MOVs only on the Line-to-Ground paths, and use GDTs on the Neutral-to-Ground side, which do act as a short circuit. This has to do with difference between static and differential resistance. Also industrial SPDs sometims use selenium cells for sustained surges.

[@eljay3993]

At 8:24 when voltage go up, the mov resistance fall, which basically mean L & N will have connection to each other.. wouldn't it blow? Because when L & N is connected it produce very high current

[@e5Group]

Bloody legend! 👍 Great breakdown

[@jockwalker24]

Good video JW, have sharpie approached you as a sponsor 😜

[@JPcostarica27]

Fluke max voltage is 600, right?

[@tomlloyd9372]

excellent !

[@dennisolsson3119]

If they fail open circuit, that could happen during a thunder storm? First few strikes are handled, then the module opens up? Are there versions that fail short circuit instead? I would rather have to investigate why the fuses blow than replacing all electronics in the house.

[@andredeswardt5717]

Great stuff JW! What size over current protection would you recommend for a 63A residential house?

[@PaulSteMarie]

What happened to your Megger? The crank unit is amusing, but I wouldn't trust it as much. It would be quite interesting to use a temperature controlled soldering iron to melt that tab and see what the actual temperature required is.

[@jwflame]

Nothing happened to it, just wasn't used in this particular video.

[@giovanninongbri2250]

When a catridge is placed is there continuity between Phase and Neutral and phase to earth and neutral to earth??

[@jwflame]

No, in normal use there is no continuity or resistance. They only conduct when higher than normal voltages are applied, typically over 275V.

[@gordonbrown2204]

The basic principle of operation seems the same as a Zenor Diode protection circuit.

[@sekharandivakaran]

Well done

[@Weaselspleen75]

I might be wrong but why have the neutral to earth part in a tncs supply? The neutral and earth are connected by a solid link before entering the consumer unit. In the event of a transient on the neutral it’s already grounded, this device wouldn’t fire on the neutral because it wouldn’t see the already grounded to earth voltage spike. Just my humble opinion-Great videos John I watch them all 👍

[@sdgelectronics]

In the instance of transients, there is a lot of high frequency content so there is a reasonable amount of impedance despite the DC resistance appearing to be low. Even less than a metre of meter tails has a measurable inductance.

[@Weaselspleen75]

Thanks for the reply although it’s hard for me to get my head round. I see this device as something that starts conducting under a certain voltage. So when it conducts it dumps the over voltage down the earth. But in a tncs setup the earth I’m talking about is permanently connected to the neutral anyway before it gets to the consumer unit. as a pen conductor the neutral and earth are the same cable back to the transformer . I can understand having this on the line side but only the line side.

[@jwflame]

At very high currents (10s of kA), connected together doesn't mean very much. Inductance can result in voltage drops of 1000+ volts for just a single metre of straight conductor.

[@Weaselspleen75]

Thanks for the reply John. I’ll put my faith in the industry boffins and will be fitting rcbo/spd boards from here on in 👍

[@pigrew]

Perhaps device failure would first cause the plastic to soften before the solder would melt? There seems to be no internal fuse, so could this start a fire if it fails and overheats just to the point that the plastic melts but not the solder? Perhaps it'll have thermal runaway and melt the solder anyway, so this wouldn't be a concern? This unit is tiny compared to the Eaton CHSPT2ULTRA I put in my house (which suggests being connected to a dedicated 50A two-pole circuit breaker). For our American split-phase system, it has both L-N and L-GND protection, and burns green LEDs while the device is still in service. They also have a model which only has L-E/N, but it's more expensive for whatever reason.

[@leexgx]

First ones used to be on a MCB but that's not required any more (just runs right off the consumer 100a isolator) as any type of amps and heat passing it melt off the solder and they cut off (for genuine spds that is as they normally only have a very small blodge of solder but they do get quite hot and they use low melting point solder ) the Neutral likely will never fail As its typically a gas discharge device but the live will always fail eventually, you can actually hear it sometimes if you put 1000v on constant test as it heats up the varistor

[@jwflame]

The types that don't require an external MCB have a fuse inside them. If that fuse fails, the SPD is useless, and no one will ever know because the fuse failing doesn't trip the mechanical indicator.

[@leexgx]

@@jwflame the fuse (normally solder as a fuse) is what is holding the indicator tab green, once it fails it gets hot and solder melts and disconnects it witch moves the tab to red, be it China ones or UK genuine branded ones

[@jwflame]

@@leexgx That solder link is a thermal overload, designed to break in the event of excessive temperature. They all have those. Types with a fuse inside have a fuse designed to fail at a specified current, they also have a fuse symbol on the side of the device, one example: www.dehn.co.uk/en-gb/1628/31262/Familie-html/31262/DEHNguardmodularwithintegratedBackupFuse.html

[@leexgx]

@@jwflame the 18th edition ones seem to have that fuse built into the spd (but very Likey still Just solder but very small amount or a fuse wire holding the tab green) I agree once it does blow it probably never get changed for long time as you could see that the MCB had tripped before (assuming the solder didn't melt first)

[@techview6933]

Great through analysis!!!

[@alunroberts1439]

could the plastic melt 1st and pull down leaving the solder to keep heating It will still show red but if no one looks each day who will know

[@azlanhaider2339]

Very informative

[@jetfu400]

So you dont need to connect it earth to work?

[@nexofilipe]

Anyone knows of this could help with induction cookers displaying error codes related with voltages?

[@burt8833]

Very informative...Thanks

[@karoly365]

7:24 You have shown SPD connected between line and neutral whereas it should be really between line and earth or between neutral and earth right? Also there cant be a scenario of the surge passing from line to neutral as in 4:03 as the common point of the two modules are connected to earth which should bypass the surge from either line or neutral right, unless earth wire is broken of course?

[@tarassu]

Why Chinese SPDs are mostly 385V but those sold in Europe usually 275V. Is there actually difference?

[@coolmanqabaha3820]

hi how r u I have a question if the SPD is shorted and damaged (shorted for ever ) then the previous C.B should be trip am right? what about coordination between devices

[@literoadie3502]

Hi John, thanks for all the videos. I've learnt a lot from you! Do you have surge protection fitted in your own house?

[@jwflame]

No, because it's an older installation and the property is rented so it's not likely the landlord would pay to install such things.

[@literoadie3502]

John Ward Thanks for the reply. I bet as an electrician, you would love to improve the installation in your own house? But the landlord won’t pay.

[@johnburns4017]

The unit tested. A normal consumer unit has usually 16mm or 25mm meter supply tails into the box. What size cable should be used on the surge protection device on a normal domestic CU?

[@jwflame]

6mm² minimum in most cases.

[@johnburns4017]

@@jwflame Thanks. I suppose the 6mm off the incomer switch with the earth and neutral off the bus bars. Would be nice if the unit could be off the L bus bar.

[@samstretton3890]

am i right in thinking that this device should defintely not have an rcbo protecting it just a regular mcb for over current?

[@benbaselet2026]

I can't think of any good reason why RC protection would not be in order, in addition to the self evident over current protection?

[@MultiPureEnergy]

Pentti Kantanen these devices leak small amounts of current to ground, more so as they age, which could cause nuisance trips of an rcbo. That is why good ones have thermal protection for the MOV, to detect when it’s getting too toasty from the leaking current.

[@Mark1024MAK]

Jacob Wells - when new and undamaged, they should not leak any significant current. Once damaged, all bets are off.

[@joezappitelli3276]

Are AC and DC compatible? Same MOV components? Thanks

[@jwflame]

The basic MOV elements will work on either AC or DC. However commercially supplied surge protection devices are intended for one or the other, and should only be used according to the manufacturer's instructions.

[@MastercraftKARIGAR]

THANKS FOR MAKING THIS VIDEO

[@TheManLab7]

Big Clive has completed gutted one buy using "reasonable force" lol. I've put one of these in my house a while ago and it's around £10-£15 delivered from China. Name brands are EXACTLY THE SAME!! All your paying for is the same, n that's it. All these new boards, you've got the choice of one with or one without and it pretty much doubles the price for something that costs a couple of quid. All these big name brand manufacturers as just raking the money in and it pisses me off! 😡 Whether if it's cheap or experience. What's inside is exactly the same!

[@millomweb]

Your globe lamp stayed on in this video ;)

[@DilnuwanAmaraweera]

Thanks you Great video

[@boonedockjourneyman7979]

How do we get a N/E transient if N and E are bonded at the service entrance panel? How would an over current device between L and N protect against a N/E “short?” Many more questions on the N/E issue. This whole area is confusing because of the N/E bond.

[@jwflame]

TT and TN-S supplies don't have that link at the panel.

[@michaelagnew7825]

Im concearned that when mov wears out (with many less severe spikes), it wouldnt always show red as solder would have to melt first. Also when mov has worn out does it give us an open circuit?

[@jwflame]

When they fail, they become more conductive, until eventually enough current flows to heat up the solder link and cause it to melt. It's a chemical compound, there isn't any realistic way it could fail open circuit.

[@rossi6329]

That was both interesting and educational. After the cartridge shorts during a power surge... Does it continue to rush the power to earth (Literally running up the meter)? Or does it cut off the power as well? When a high flow of voltage comes through and causes the compound to be conductive, does it revert to it's original state later on?

[@jwflame]

It's effectively a short circuit for the duration of the surge, and returns to a very high resistance afterwards. However that duration is typically measured in microseconds so the energy dissipated is far too small to make any difference to meter readings.

[@rossi6329]

@@jwflame Aren't these one time/ replaceable cartridges? Or as you said it returns to being non conductive after it Earth's a surge. So continues to do is job again even when the indicator is red?

[@robertmccully2792]

If it works off heat you should be able to make it fail with a heat amps calculation.

[@gustavfenk4021]

Test them to see if they work in real-world conditions: kite, thunderstorm, etc.: like Benjamin Franklin. :-)

[@jovetj]

Franklin didn't actually do the "key" experiment. But something similar was done, inspired by his idea, with a high metal pole in France.

[@DjResR]

Use a balloon, works better._

[@seanpassant3174]

All SPD's in the EU have to comply with the testing protocol in IEC 61643 and this means they are tested, regularly and vigorously. You should always ensure you get confirmation from your supplier that their SPD meets the requirements of IEC 61643

[@llVIU]

strange coffee maker you have there john, it outputs 600 volts to grind the beans?

[@rooselectrix4846]

I've heard stories about these SPDs failing. Apparently the surge has been known to bypass the MOV completely and fry the installation anyway. Not sure whether or not SPDs were from a reputable manufacturer. here in Malta we are obliged to insert an overvoltage and undervoltage relay between the DP MCB and RCD at the origin of the installation. I dare say that the relay is a safer/ more reliable option.

[@bdf2718]

I dare say that the relay is a *much* slower option and therefore a much more *useless* option.

[@rooselectrix4846]

@@bdf2718 but I would think that an OVR is never 'spent' and therefore always affords an element of protection. From what I can understand an SPD can be spent and go undetected thus giving a false sense of security. Is that right?

[@bdf2718]

@@rooselectrix4846 OVR might protect you against the sort of line faults that put an extra 50V on the line. It operates in a millisecond or two (if it's a fast one), and your equipment can probably survive that (filament lamps and heaters almost certainly, electonics maybe). John was talking of higher voltage transients that last for microseconds to milliseconds. By the time your OVR opens, the damage has been done. The problem with MOVs is that they degrade a little when they deal with a transient and eventually wear out. But before they wear out they handle things your OVR can't.

[@jwflame]

Overvoltage relays/trips are for entirely different types of problem,, and are useless with transients - far too slow to react, and it's not desirable to cut off the supply if a transient occurs. SPDs are useless with overvoltages which last more than a few milliseconds - they will be destroyed. As is always the case, it's about selecting the correct type of protection for the problems that are likely to occur.

[@rooselectrix4846]

@@bdf2718 I have another question, if I may. In Malta most meters come with an incorporated 40A DP MCB (it is 40A, true). I was thinking that perhaps these SPDs could be fitted 1st thing after the meter, take the tails and main earth into it and connect the rest of the installation in parallel. It would look something like: meter -> SPD -> DP MCB (or main switch) -> rest of the installation. Does that make sense?

[@ruipaulofsantos]

In the last clover my varistor went short, but it didn't interrupt the connection ... chinese stuff ?? !!

[@insylem]

I saw the aftermath of one of those exploding