Fuse blown and neutral wire sheathing melted.

[Jimmy Jones 1234]

Which wires, where exactly? Post clear close-up pics. Need to distinguish between bad connections at the terminals and any other kind of problem such as bad contact inside the circuit breakers.

Hi - could you see the video? That shows the sparks. I cleaned everythin in here, cicrcuit breakers, terminals + even bought a new terminal but it looks like hell now. It is the very top wire which I believe you figured out last time was neutral from the outside feed into the house which you were concerned might be loose outside and then I'd have a problem with 400w? Jeez, complicated. i have cleaned and made all the wires look nice but now everything looks crappy again, melted, dangerous, again. but unfortunately, this is like a snowball- now I am hearing pops and sizzles every few minutes.I turned off one of the fuses (the one on the right) and now it is quiet, it's the fridge and sockets in the kitchen. I plug the fridge into an extention lead but I am not convinced it's the fridge - nothing else was working at this time only the fridge, it's a small draw.
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Which wires, where exactly? Post clear close-up pics. Need to distinguish between bad connections at the terminals and any other kind of problem such as bad contact inside the circuit breakers.

Okay, at the moment i have figured out that the right hand fuse which feeds the kitchen sockets 'sparks' when i plug something into the kitchen sockets. The fridge is now plugged into an extension to another room. So the sockets in the kitchen are off basically. And no sparking.
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Hi - could you see the video? That shows the sparks. I cleaned everythin in here, cicrcuit breakers, terminals + even bought a new terminal but it looks like hell now. It is the very top wire which I believe you figured out last time was neutral from the outside feed into the house which you were concerned might be loose outside and then I'd have a problem with 400w? Jeez, complicated. i have cleaned and made all the wires look nice but now everything looks crappy again, melted, dangerous, again. but unfortunately, this is like a snowball- now I am hearing pops and sizzles every few minutes.I turned off one of the fuses (the one on the right) and now it is quiet, it's the fridge and sockets in the kitchen. I plug the fridge into an extention lead but I am not convinced it's the fridge - nothing else was working at this time only the fridge, it's a small draw.
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Okay, at the moment i have figured out that the right hand fuse which feeds the kitchen sockets 'sparks' when i plug something into the kitchen sockets. The fridge is now plugged into an extension to another room. So the sockets in the kitchen are off basically. And no sparking.

But, if I turn the fuse on and plug somthing in with power - the cable sparks like in the video...
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Hi - could you see the video? That shows the sparks. I cleaned everythin in here, cicrcuit breakers, terminals + even bought a new terminal but it looks like hell now. It is the very top wire which I believe you figured out last time was neutral from the outside feed into the house which you were concerned might be loose outside and then I'd have a problem with 400w? Jeez, complicated. i have cleaned and made all the wires look nice but now everything looks crappy again, melted, dangerous, again. but unfortunately, this is like a snowball- now I am hearing pops and sizzles every few minutes.I turned off one of the fuses (the one on the right) and now it is quiet, it's the fridge and sockets in the kitchen. I plug the fridge into an extention lead but I am not convinced it's the fridge - nothing else was working at this time only the fridge, it's a small draw.
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Okay, at the moment i have figured out that the right hand fuse which feeds the kitchen sockets 'sparks' when i plug something into the kitchen sockets. The fridge is now plugged into an extension to another room. So the sockets in the kitchen are off basically. And no sparking.
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But, if I turn the fuse on and plug somthing in with power - the cable sparks like in the video...

Lucien?

 

[Pete999]

Hi guys, hope you can try to shed some light on what might be the problem. Basically nothing is new, all been the same for 3 years since we moved in but over the past few days when the dishwasher was on (or anything plugged into a socket in the kitchen) I noticed a burning plastic smell. Couldn't figure out what it was until a fuse tripped the other day (popped actually - I thought a lamp bulb had blown), I opened up the fuse box panel in the gypsum wall and saw the melted plastic fuse box cover, took that off and saw melted plastic on the wires. The fuse on the right is what tripped but it only has the kitchen sockets on it, nothing big on here only a fridge and the dishwasher, from time to time the toaster and kettle. The one in the middle serves the bathroom lights and on the power to the corridor. There aren't any big loads here at all. I can't figure out why the plastic would melt like this. I tested it again and when I plug anything for long term (like the dishwasher) the fuse gets warm and then eventually hot and I'm guessing will trip again.

I will call an electrician obviously, but when the 'Corona virus' is over, not now - I'm staying home and not inviting strangers to my home either. I have kept the fuse off for now and using an extension lead for the appliances from another socket in the next room.

Attached is a picture.View attachment 56699

I see no picture

 

[ChrisElectrical88]

Are you actually in Estonia? I can see any pictures on the tread due to the time since the OP, any chance of some recent ones?

 

[pc1966]

The photos have gone from this site - as have all older photos on all threads - for reasons best known to Dan, etc.

I was sent the video by PM, but it would be more useful posted here. It shows what looks (from memory) like the original setup from the start of the thread but arcing on the top wire. Clearly a bad connection at that screw terminal, either not correctly tightened or the wire has developed some sort of high resistance layer on it now.

Without having a copy of the original photos for comparison I can't say if the terminal strip was replaced, but the OP says he did. Either way it needs replaced again due to the heat damage, and the cables look poorly as well.

Some photos posted here might help. The OP is in a difficult situation due to COVID19 but really it is looking like a job for a professional to replace the lot with wires properly joined further back where (hopefully) they are undamaged.
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It is a very serious issue, as they use TN-C so this bad connection on the supply PEN would make the appliances live.

Really the supply to that board should be switched off until it is fixed.

 

[Lucien Nunes]

I see nothing either.

@Chriselectrical yes the installation is in Estonia. The fault is in a small DB in the house with three B16 MCBs, one on each phase, fed TN-C from a cabinet in the garage which is normal Soviet era stuff with 25A TP 4-wire intake and submain. There had been some overheating at the CNE bar in the sub board and we suggested remaking all the connections carefully with freshly prepared ends, paying special attention to the CNE itself.

The fact that the connections are arcing again makes me wonder whether one or more of those cables are aluminium after all. There was debate as to whether it was tinned copper or ali.

 

[Mike Johnson]

The photos have gone from this site - as have all older photos on all threads - for reasons best known to Dan, etc.

But still hundreds of adverts even between posts?

 

[Jimmy Jones 1234]

I see no picture

There is a video in my original post.
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Here is the video again.

 

[Lucien Nunes]

That's a pretty extreme example of a bad connection!

EDIT: That appears to be the submain CNE, i.e. combined neutral / earth incoming from the other panel. If it is, this is a dangerous situation that could give you electric shocks from your appliances or at the very least damage them.

As advised by PC1966, please switch off the power and get an electrician on to this immediately. I can't recommend any other approach.

 

[Mike Johnson]

Don't you all think we ought to tell him that in the interim he should turn off at the incoming main and tighten the terminal?

 

[Lucien Nunes]

That was our recommendation first time around. For whatever reason, the neutral bar has burnt out again. If it were a line or neutral then yes, but as it is a CNE then the risks arising from a high-resistance connection are that much greater and I don't feel it's appropriate to recommend DIY repair of a burnt-out CNE where the cable is damaged.

 

[Mike Johnson]

I appreciate that, but it does look as though the terminal is just not making contact? Perhaps the terminal screw is jammed, taking it out and cleaning it may allow the terminal to screw in further and make contact, I just think that anything is worth a try if he is unable to get an electrician to his place due to lockdown.

 

[Lucien Nunes]

I think you're right Mike, you or I would give it a twist and probably know by the feel whether the contact is adequate. But I would not phrase it as a recommendation simply to save the OP the cost of having it rectified by a professional.

 

[freddo]

From that video the whole lot looks like a disaster area, the conductors and bar are badly damaged, a real risk of fire and electric shock.

 

[Jimmy Jones 1234]

Hi guys, I replaced everything this time around instead of just cleaning up the wires and terminals etc, I have put in a new wago terminal block, new fuses and new wires from the terminal block back to the wago fittings back to the wago fittings buried in the left hand side of the wall. Having stripped back a bit of the incoming cable the wire that goes in the terminal block actually does appear to be aluminium and is much thinner than the three cables going in the top of the fuses. Picture attached - hope it looks okay to you pros, I will monitor it and see if the same thing happens again then I'll get the electrician in to change that cable out.

 

[Mike Johnson]

That looks better, but the incoming cables still look suspect, have it done sooner rather than later I would suggest.

 

[Jimmy Jones 1234]

That looks better, but the incoming cables still look suspect, have it done sooner rather than later I would suggest.

Thanks - I haven't put the cover on the front yet since i want to keep an eye on it and see how it goes. Weird thing is that i have lived in this house for 4 years and this only started earlier in the year. Before that it was open - no drywall or anything so you could see the fuses and cables openly (and splash god forbid with anything in the kitchen area) - this is in the kitchen. This only started after, or at least I noticed it, after I had put new drywall over everything last year. Odd that it didn't do this much earlier.

I was wondering if there might be a loose connection on this mains cable outside in the mains box (it's in the garage) that could affect what is happening inside? But I'm a bit afraid to touch anything out there without a huge life insurance policy

 

[pc1966]

It is fairly common to have the neutral thinner than the line (phase) conductors in a 3-phase system as usually there is some cancellation of the currents where the 3 loads join the neutral. With 3 identical (linear) loads you get zero neutral current back to the source, but that is the ideal case.

Still if it is aluminium wire it has all sorts of additional issues to maintain a reliable connection as it tends to compress more, has greater risk of galvanic corrosion, etc.

The spring loaded Wago style is a good start as they tend to maintain constant pressure. Other advice is to keep the joint dry (or use jointing compound) to reduce any tendency to corrosion. Still, I think Wagos are rated for Al wire (at least I seem to remember on a USA page).

For peace of mind I would check in a few days the connections are still sound (more so screw terminals on MCBs), obviously with power off! Don't over-tighten them, but make sure the are not loose. I know that is hardly a useful description but short of getting a torque screwdriver its the best I could do!

 

[Lucien Nunes]

That looks good! I would definitely use aluminium jointing paste on the incoming cable though, Wagos are suitable for aluminium provided you do so. Their product is called 'Alu-plus', it prevents corrosion and electrolysis and will reduce the chances of it going high-resistance and overheating. It comes in a syringe that you use to fill the entry hole of the connector. After cleaning the end of the cable, insert it into the connector immediately, before the oxide layer builds up. You'll only use 1% of the tube of paste but I think it's worth it and the joint should then last the remaining life of the cable.

One other subtlety to do with the neutral bar, you might choose to rework or ignore...

I think the bar is made up of three 5-way connectors linked togther. At the moment, because of the layout of the outgoing neutrals and earths, the top link adds two joints and therefore points of failure to the CNE. I appreciate it's probably the most reliable connection in the box, but if it were to fail (perhaps due to heating from the aluminium connection) two of the earths might remain connected to the earthed incoming cable while the other two are connected to floating neutrals which will become live, creating a significant shock risk between different appliances in the home.

What I would do is put all four earths in the top block, all four neutrals in the bottom, and the incoming cable in the middle. That way the two joints formed by each link only carry neutral or earth, not both. If heating from the aluminium cable joint caused a failure of the middle contact block, even if the earths become disconnected from earth, at least they remain connected together. Another advantage of placing the aluminium incoming cable in one of the three middle entry points of a Wago is that there is twice the cross-sectional area of metal inside to conduct heat away from it, helping to reduce the rate of deterioration if it runs warm.

 

[pc1966]

This is the stuff Lucien mentioned from an Estonian supplier:

http://www.westbalt.eu/store/index.php/contact-paste-wago-alu-plus-20ml.html

I was wondering if it would be feasible to run a 2nd parallel neutral/earth wire back to the incoming board? Probably too big a job really, as it looks like what you now have is a lot more reliable than the original set-up anyway.
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Also if you do get the contact paste, I would apply some of it to the aluminium wire at the MCB as well.

 

[Lucien Nunes]

I like to scrub the end of the conductor with paste and then wipe most of it off, so that the surface doesn't get a chance to oxidise before the connection is made as it is always covered in paste. This is normal practice for jointing ali busbars.

Bauhaus also have it
Alu-plus at Bauhaus

This is not advice or a recommendation to the OP but personally what I would do is to rearrange for the CNE to be one of the larger conductors, and to make two separate joints to the conductor without cutting it. I'd strip off some insulation and pass it through a clamp to which I could connect the earth, then continue the run into a second terminal for the neutral. That way although the conductor is serving as a CNE, the joints (which are much more likely to fail than the cable run) are not. I'd make a similar double-joint at the supply end, although those would be part of the CNE.

The Soviet / Russian equivalent of the European line tap is the «ореx» (orekh) meaning 'nut'. Not as in a thing you screw on like a wirenut, but as in something inside two half-shells that split apart. I rather like them. You can make a connection to an unbroken conductor which, unlike a line tap, is clamped separately to the tap so the two can be different metals. So when you have an ali CNE running up your riser, you can pass it through two oрехи, one to tap off a copper neutral and another for the earth, and in each case have the security of four clamping screws applying strong, even pressure onto the ali conductor.

Scroll down this link for pics:
Russian 'nut' tap connectors