Having already taken a look at some cheap surge protective devices like this generic Chinese one with so many problems, it's not even worth talking about. uh I thought I'd take a look at a really expensive British one for typical British consumer units or distribution boards and this one is interesting because it's double pull. it protects from live to neutral and Earth and it also has this uh feedback thing and if you look at the bottom it's got little pins that stick out of here that going through holes at the bottom here and it will actually tell you if the unit has been removed or if it's actually tripped and I can hear when I put this in I can hear slight click of micro switches. this connector comes out so you can basically wire it into a feedback system that warns you when the protection has failed, which is quite useful.

I Should hope it would have nice features because this thing has a current list price of over 92 pounds compared to the one that looks identical by Ylax which is just another rebranding of the same unit probably which is 80 pounds I think and British general who sell one for 30 pounds and even MK are a bargain about 35 pounds although their unit is wider but having said that that might be might be a good thing. So here's a bit we're interested in. It's this bit here on not sure how easy this is going to be to open I can see a little latch here so we'll shove this spudger into it and I want to mention I did not pay I did not pay 80 pounds for this or 90 pounds. What was it? 92 pounds which is about 115 American dollars? Uh I didn't pay that for it I bought it on eBay Someone was selling random electrical items and this was one of them.

This is not coming out. Let me try and jam a screwdriver into it without appealing myself in the process. If this fails, this is very late to peel me. If this fails, I shall pause momentarily while I try to open this up, but I'll just kind of break this seal and then I can we can pull it apart together one moment? please? Well That took unreasonable Force So this is not going back together soon.

That's all right. let's get down, have a close look in the process. I Took a wee sneak peek inside and so there are little soda uh bits. the the release mechanisms the the over temperature mechanisms, the safety cutouts that fire these pins up.

So I've got the soldier iron on I've also pre-drilled these so we can open that after as well. So if I slide this out, we have an odd Arrangement Here we have a small metal oxide varista in this side, just sandwiched in. Uh, well. let's get those screws out.

and well, that's trigger the mechanisms first because there's the multiple link on this side and there's a multiple Link in this side. The live seems to go up through this large metal oxide. Barista Link across and it goes down to the other side and then let me just double check this. This goes in like this.

so the Earth connection is going to this little one and the neutral connection is going to the bigger one. I Wonder why they've used different sized ones? Well cast and space? Probably. But the current flows up these pins well. it's AC The current flows via these pins through this mechanism here and these little green flags that say everything is okay.

When the red thing goes up, it physically pushes those little flaps up and out the way. So let's do that. Let's trigger it. So I'm going to pretend this one's overheating by putting my Soldier iron on like this.

This could take a while. this is taking a while. Hold on. Let me wet it with fresh soda I Have fresh soda here I Shall put a little blob on like that and we shall overheat it I wonder what temperature this triggers at? So it's Heating it's hidden.

It's not triggering Is it? It's going to take quite a temperature. It's got quite a mass before that triggers. That's a bit awkward. It's like waiting for paint to dry.

Yeah, that's not happening. Is it okay? Tell you what. Let's try the other side. This one may be easier.

So I'm going to wipe the solder on again I Have to make at least one of them trigger before I take it apart. Let's try this one. Let's see what: Ping The solder everywhere. No, that is quite a high temperature I Think it is kind of melting, but it's having to heat the whole metal oxide varista.

which is the opposite because normally the whole metal oxide Barista would be heating it. that is not. It's triggered so it's now gone up and it's pushed the green flap uh into the side and the red is now the most prominent, but a ticket that's hidden by the window. Now let's push it and see what it looks like.

Now it's tripped. Here's what it looks like once it's tripped. Oh the little green thing. Oh, any red replace So the green is still there, but there's the red showing right? Okay, that's that resolved, right.

And also that pin. the red pin has pinged in now I can't get this back out again? Splendid Oh no I really have jammed it shut again, haven't I Let's see if I can not stab myself in the process of getting this back out. Spudger Spudger Spudger. Get the spudger in and prize it out there.

We go right. Let's get the rest of it to bits. I may have to melt that other soda link to actually do that. or I can just, uh, undo these screws here.

Do you have a suitable screwdriver? Do I have a suitable screwdriver? I Think my super screwdriver? is. Hey, this is because I've been away so long, everything is disorganized. This will do this. Will do so.

Here is one plate connecting to this Matlock's Everesture on the Earth side with its little mini one. Is that smart in the one in the cheap generic knockoffie type thing? Hmm. definitely smarter than the one in the oh, it's loose in the oh, it pops right out. That's quite nice.

It's a little metallox Everest or air. It says Epcos. Oh I'm gonna need them to magnifying glass to read that. It says Epcos 620.

hold on, let's see if I can make that light up. Epcos 620. Okay, I know that red one is pinged up as well. Let's get these bits out of the way and take a look at them.

Oh, there is the little braided bit going up to that right? So we can now theoretically hinge this one up and take a look at this big thing. Whatever this is, it's a big flat metal oxide barista. Oh, that's a monster. I Think it's dipped in a resin.

Um, is this going to come off with a application of a knife? Oh, this one also says oh no it doesn't It doesn't say of course it says e-u-y-e-l-e-c-e-u-yelec at 3 4 SK 431 The Four Three one um is the voltage 430 volts D4 as K3 for abnormally expect to be the size? Oh yeah, reasonable enough. So 3 4 Square it's a square metal oxide barista. See if I can peel some of this off or is it is. It's actually it's baked on.

Oh no no maybe it's not. Am I going to stab myself? It has been done before. Is there any point taking this off? It's revealing a big metal plate which is probably soldered onto either side of the metal oxide varista. Yeah, this plate is just sorted on.

so this is basically a square slab of the material with this plate just soldered onto the side. and if I peel a bit the end off, you'll see the ceramicy stuff. If I can peel, peel a bit, the end off. No, that it's not going to peel off, Is it? Nope.

Nope. It's mated firmly onto the ceramic. But just imagine there's this stuff inside radio. Now we've seen what's in that bit.

Let's get this open. This is where it's going to Ping apart. It's gonna ping because it feels like it should look spring-loaded things in it. Let's use Force Use the force.

Reason: I Saw a picture of Darth Vader sitting in a toilet with use the Fortune I Thought it was quite funny actually. Uh, is this going to come out? Is this going to come out? Yes it is. It's I've got a little circuit board there with micro switches. Look at that, hold on, get out.

Oh I'll just lift the module out. Oh, just spend the heart like that and lift this out. It's a little circuit board which may be glued in. Oh no, it's actually it's two parts here because the there's two little micro switches here jammed.

uh, between uh, two parts. So I'm gonna have to split this here as well. Split it without splitting fingers. Oh, this has still got, uh, most of a rivet going through it, so that's not really going to help.

Tail watch one moment, please. That was very hard to get out because the whole housing was such that the it looks like the actual switches themselves have been sat into place in the plastic housing and then the circuit board put up and soldered quite well put together. I've also discovered something else. The common connection here is the neutral.

Um, and I'll show you I'll show you in the schematic. That's the best bit. I'm glad I didn't pay full price for this. that would have been that would have been a very expensive video.

Yes, glad I didn't pay the full whack for that. Here is the schematic. Let me Zoom down this so we'll start off with the metal oxide roosters themselves. The neutral connection has a thermal fuse and then it feeds the end of both of the metal oxide wrists.

There's a big one and there's a small one. The big one then goes straight to live so that if this one starts heating up, it should trip the neutral connection and sort of break the circuit. Though it would technically mean that there'd be some protection between live to Earth But there's also thermal fuse there. However, there is also a thermal fuse in the earth and the neutral goes through that therm that thermal fuse and feeds the live one.

and also the Earth one which is a smaller one. And then it's got that thermal fuse. The switches are quite clever, and this was probably one of the most sophisticated bits of it, really. but not really.

It was. Deciding the size of these I mean this is a monster. This metal Ox overestra. It's a really big one.

I wasn't expecting that and I Guess really. The Chancellor being a significant voltage between neutral and Earth is fairly low. It's more likely to occur in TT type systems. Um, but that could also happen when you have the failed Um electrical distribution system where they lose the combined neutral and Earth the Tncs.

It's a really common failure these days that suddenly all the houses neighborhood will become live. With respect to General Earth it's not a good thing. cable joints, they're not necessarily well designed. Anyway, here's the switching mechanism.

You've got. The common connection comes in and these are the two switches and in the green position, everything is good. In the red position, one of them is tripped and it's bad. So the common comes through links through this good switch.

contact Loops across goes through this good contact. and then goes to the good connection. So as long as the switch is in the right position, the Comm will be connected to good and it shows that the surge arrester is still in the circuit. If any of them trips any at all the Common: In this instance that this one a trip, the Comm will go through the red and it'll go straight over to the trip, but also because it's tripped.

Overall, break the circuit over to the good connections so it decisively shows from common to tripped that one of them has failed. If this is the one that that trips, uh, then you're going to get a connection through here. it's going to go across to here Loop through and then it's because it's tripped over. It's not going to go out good.

It's actually going to go out tripped again. It's a very clever interlocking system, but there we have it. Uh, The Surge Suppressors They're something that is being mandated nowadays I Think it's more to protect against huge expenses of the utility industry having these cable faults and uh, so the cost can be deferred up to up to the users instead when it blows up their expensive little modules. Not that people will check that the indicators in them are good, but um, it's something that's been mandated these days and when you mandate something, then they can charge whatever they like so they shouldn't really be that expensive.

I Think the if anything, the uh British general one and the MK One represent good value. That could be in the sense that that's a replaceable module I'm not sure I'm not sure, but you can buy the whole thing and just pull the module out and plug it into the holder. It might make sense to choose their distribution boards at this point in time, just because it's more cost effective to change components like that. But there we have it.

Uh, the inside of a double pole British Compliant surge protection device.