Burning neutral connections

[electric will]

Hi, just been over the road to look at a neighbours cooker not working, font the neutral in the cooker control unit burnt, load side, most likely caused by loose terminal as the others wasn't very tight.
but how come it seems to be normally the neutral connection that burns first, ie shower pull cords, consumer unit neutral bars? This is only single phase I'm talking about
the current is the same as on the line.

 

[Octopus]

Loose connection probably

 

[Darkwood]

Its just your own findings that suggest this ive seen equal quantity of live and neutral overheated cables over my 20 odd years, poor termination will lead to heat damage more so with heavier loads but if you find your experiencing a neutral trend then i suspect coincidence on your part as with the many thousands of sparkies on here i would have expected many similar threads if it were the case.

 

[electric will]

It was a loose connection im sure but what I'm saying is im finding it's nearly always the neutral that fails in say shower pull cords etc

 

[SPARTYKUS]

Maybe people view the neutral not quite as important as the scary bright red one! And therefore don't tighten it up properly.


When I say "people" really I mean "performers of muppetry"

 

[electric will]

Maybe people view the neutral not quite as important as the scary bright red one! And therefore don't tighten it up properly.


When I say "people" really I mean "performers of muppetry"

Yeah bit like the it's only the earth attitude

 

[Darkwood]

Yes understood what you are finding but just expressing in the examples you give its just coincidence you have had a trend in favour of the neutral..... had it been the incoming neutrals on busbars, submains or certain circuits in commercial and industrial then my answer would have been different as the neutral becomes suseptable to burning out due to issues like Harmonics which is becoming a growing issue due to the heavier use nowadays of electronics in everything from computers to lighting and speed controls of motors.

 

[sparks1973]

Yeah bit like the it's only the earth attitude

na...they tend to just snip them off.....

 

[sparks1973]

Yes understood what you are finding but just expressing in the examples you give its just coincidence you have had a trend in favour of the neutral..... had it been the incoming neutrals on busbars, submains or certain circuits in commercial and industrial then my answer would have been different as the neutral becomes suseptable to burning out due to issues like Harmonics which is becoming a growing issue due to the heavier use nowadays of electronics in everything from computers to lighting and speed controls of motors.

from what i`v heard DNOs are getting in a real flap about this as well Dark...

 

[Darkwood]

Yes it can burn out the transformers and creates network issues too but up to press they seem to be coping, i requested a supply upgrade for three large machines i was wiring and now it down to me to either work out any possible Harmonic issues and or have a analysis done to ensure the company isn't sending Harmonics into the network as its now in their submission paperwork that it down the requester to confirm Harmonic compliance.

 

[Dooby]

Maybe people view the neutral not quite as important as the scary bright red one! And therefore don't tighten it up properly.

When I say "people" really I mean "performers of muppetry"

Oh I was just about to reply just this thinking I could seem a total genius, but you got in first dammit.

I've found in a box like a cooker where it's just load/supply the neutral isn't given the same rigourous tightening. Though in something like a coffin box with loads of connections, if the neutrals are loose they're all loose, that's just someone who can't be arsed.

 

[ayjay]

i think -a lot of the time, the hole in the term is too big-and the conductor is too thin, the poor method of a simple screw that tightens up, goes to one side of the conductor
the conductor in some cases can be pulled out even if the screw is tighned
--------------
take 25mm tails for instance-tighten the terms as much as you can on a c/u -then
pull on the bug---s they come out!
i installed a new c/u once and tightened the mainswitch hexagon screw so tight with a hexagon wrench the whole teminal snapped off

 

[DPG]

I've heard stories years ago about the same thing happening, ie. loose neutrals, in the old-style mains plugs (the knurled-screw MK type). I can't remember what the theories were but I'll try and search on the web for it. Daz

 

[malcolmsanford]

DW is spot on with harmonics, and what we have to remember is that single phase systems are also susceptible to Triplen harmonics especially today where so many domestic/commercial pieces of equipment utilize switch-mode power supplies. This is a good read

REO UK - Taming Harmonics