Fuse box fire with photos

[uksparks]

I like Hager, I've just put an Invicta 3, 4 way board, three phase in to the board then split all onto single phases for storage heaters, this is in a domestic setting. See photo below, it was obviously not complete at this point, but feel free to comment...



I am putting a metalclad MK box below for the 24 hour box. You may say why didn't i use the channel thing at the top of the Hager box, well it visually looked better doing what I did, i put 50mm pipes up the wall and put the cables in that and fed it straight into the back of the box.

 

[Taylortwocities]

I don't have a postcard handy but the load on the live and neutral is often not equal unless the load is linear. Think harmonics

I hadn't considered harmonics to be an issue on an electric shower....My
theory is that showers and immersions tend to be installed by jobbing plumbers - the little treasures!

 

[HandySparks]

I don't have a postcard handy but the load on the live and neutral is often not equal unless the load is linear. Think harmonics

In a single phase circuit, line and neutral will always be the same, won't they? Apologies if I'm taking seriously, something that was said in jest.

 

[SPARKY89]

it seems that this is a school boy error the screw terminals have not been tighten so as a result caused arcing

 

[Phoenix]

My old man told me years ago that 'most of your problems will be on the Neutral' don't know why, but to date I've found that to be good advice. I would love to know if others find this to be the case, and why...

 

[DPG]

I remember this debate years ago but relating to 13A plugs. The neutral in these was found to be loose much more than the live was. Can't remember what the outcome was and can't be ar*ed to wade through loads of tripe on Google though Daz

 

[Tiny Spark]

My guess would be that the neutral in a plug top is bent back on itself and when done by your average DIY'er nearly always across the top of the earth which puts it in a funny angle and causes stress on the conductor.

Just a theory like but I have found more badly terminated neutrals this way than any other.

 

[telectrix]

for some strange reason, it's usually the neutral that gets burnt. went today on a problem with a 2.2kW grill on a plug. customer complained that the plug was too hot to touch. on stripping down, found the N pin burnt both on the plug and in the socket. was coming close to meltdown. swapped the socket for a 20A D/P switch and hard wired appliance. ( circuit in 6mm on own 32A MCB) .

 

[DPG]

There was a theory, with the plug-tops, that the neutral connection got more stress from plugging/unplugging as it was directly onto the rectangular prong of the plug. The live on the other hand is 'isolated' mechanically by the fuse (no direct connection to the prong). Not sure I go with this, but it is an obvious difference. Daz

 

[Tiny Spark]

There was a theory, with the plug-tops, that the neutral connection got more stress from plugging/unplugging as it was directly onto the rectangular prong of the plug. The live on the other hand is 'isolated' mechanically by the fuse (no direct connection to the prong). Not sure I go with this, but it is an obvious difference. Daz

Although I can see the logic if the plug is decent then the neutral pin should not move at all.
The plugs we use have the pins locked in place by little plastic hooks, However I have seen some really **** plugs.

The worst ones being those stupid clamp down type where you have to bend the wire around the pin and then a little nut screws down ontop to hold them in place.

 

[bigdavs83]

Possibly overtightened screw on the neutral which has split the bar and over the years has eventually arced its way clear and hey presto up she goes! Seen it on 3 phase boards where the goon doing the maintenance just has to get the final tighten on the screw and splits the busbar 6 months later monitors and computers have smoke piling out of them cos there's no neutral path back to the db

 

[DPG]

Although I can see the logic if the plug is decent then the neutral pin should not move at all.
The plugs we use have the pins locked in place by little plastic hooks, However I have seen some really **** plugs.

The worst ones being those stupid clamp down type where you have to bend the wire around the pin and then a little nut screws down ontop to hold them in place.

The MK ones that use that method are good plugs. Daz

 

[Tiny Spark]

The MK ones that use that method are good plugs. Daz

Think the ones we tried were MK, Cant say I was approving.
You wrap the wire around which takes forever and fidly as hell then when you clamp the nut down the strands seperate and spill out of the side.

Duraplug is where its at

 

[brman]

I'd guess neutral at the plug for the stress reasons given and neutral at the board because it is a much smaller screw/clamp than the line which is normally a proper cage clamp in the MCB.
Just a guess though.......

 

[GLENNSPARK]

What are protex boards?? They sound rubbish

yeah they are..
check out how the breakers sit next to each other in the pics...

i had to replace an RCD on a protec last week...and it was the same...

totally crap boards these...
there were a lot of em fitted on the 16th...

 

[GLENNSPARK]

I'd guess neutral at the plug for the stress reasons given and neutral at the board because it is a much smaller screw/clamp than the line which is normally a proper cage clamp in the MCB.
Just a guess though.......

the terminal screws on these protec`s are seriously chud....
in fact the whole thing is a bunch of chud...

 

[Marvo]

I hadn't considered harmonics to be an issue on an electric shower....My
theory is that showers and immersions tend to be installed by jobbing plumbers - the little treasures!

In a single phase circuit, line and neutral will always be the same, won't they? Apologies if I'm taking seriously, something that was said in jest.

Apologies, I didn't read the post correctly, yes in a single phase supply it will be same. In these cases I guess it's a combination of an inferior connection method as already stated because the live has a caged clamp whereas the N is often directly under a screw. Secondly, especially in the UK I don't read much about a Neutral or loop impedance test being done, yes you do R1 + R2 but the neutral seems like it's pretty much exempt from testing under UK requirements so overtightened and undertightened connections are more likely to slip through the net on the neutral side.

 

[Geordie Spark]

Why is the Main Switch still closed ( piccies1 & 3 ) ??

 

[HandySparks]

Secondly, especially in the UK I don't read much about a Neutral or loop impedance test being done, yes you do R1 + R2 but the neutral seems like it's pretty much exempt from testing under UK requirements....

Yes, I've wondered about that for a while. Seems a bit of a dropoff to me that checking the neutral isn't required, apart from continuity of ring final circuit conductors. When I'm testing Zs, I'll often check the line impedance at the same time. It's a very quick test to do with my Fluke. I don't write the results down on the final EIC or EICR form because there's no space for it, but I'll check that the figure seems reasonable.

 

[uksparks]

I switched it off after taking these initial photos, believe it or not, the client had removed the front and switch the isolator off. I switched this off after i took the photos and also locked the isolator off and put a warning sign on it. I didn't get the job to fix it as they wanted it doing there and then and it was 4:30pm and I said I can do Friday, so day after next, and they didn't want that so not much I could offer really. I don't know about you but I personally wouldn't take on changing a board that late in the day when the light was starting to go. Not only that I needed my big steps to reach the high ceiling which I had not got with me.