Burnt neutrals

[baldsparkies]

Why is it always the neutral that overheats on shower pull switches? I've never seen a burnt live conductor.

I love shower threads so !!

Once current has flowed through a fixed resistance the returning voltage drops.
That drop in voltage creates a back emf that is harmonically amplified by an increase in current.

Now the harmonics become resonant, and over time create mechanical vibration that work the terminal screws loose.
This in turn creates a bad connection producing heat.

So effectively if line and neutral are torqued to equal values, over time it is the neutral that becomes susceptible to a loose connection. :icon12:

 

[Jonspark]

I love shower threads so !!

Once current has flowed through a fixed resistance the returning voltage drops.
That drop in voltage creates a back emf that is harmonically amplified by an increase in current.

Now the harmonics become resonant, and over time create mechanical vibration that work the terminal screws loose.
This in turn creates a bad connection producing heat.

So effectively if line and neutral are torqued to equal values, over time it is the neutral that becomes susceptible to a loose connection. :icon12:

And you win tonight's star prize for the correct answer.

 

[NickD]

Why is it always the neutral that overheats on shower pull switches? I've never seen a burnt live conductor.

Standard R1+R2 testing on a radial carries out no test on the neutral therefore no poor connection in the neutral will ever be picked up. I'm sceptical about this having any kind of statistically significant part to play though.

You have to bear in mind that on AC, if you ignore potential difference to earth, the neutral spends exactly half of its time being the 'live', really

 

[willy fixit]

Ha!

 

[NickD]

Suddenly I could murder a milk chocolate Aero.

 

[cotty]

Ha!

Haemorrhoids on the split ring

 

[Silly Sausage]

Woodchip, I'm getting a 70s flashback!!!

 

[NickD]

Who did the cutting in on that dark coloured wall paint? Awful.

 

[TJ Anderson]

Don't ya just love the insulation tape on the cpc's. Sign of a quality job right there.

 

[stevethesparks]

Next thing will be fire proof accessories - due to poorly terminated cables.:bobby:

 

[HappyHippyDad]

I love shower threads so !!

Once current has flowed through a fixed resistance the returning voltage drops.
That drop in voltage creates a back emf that is harmonically amplified by an increase in current.

Now the harmonics become resonant, and over time create mechanical vibration that work the terminal screws loose.
This in turn creates a bad connection producing heat.

So effectively if line and neutral are torqued to equal values, over time it is the neutral that becomes susceptible to a loose connection. :icon12:

You're going to have to tell me if you're joking? I don't mind admitting I just don't know if you are or not!!

I don't think I'm going to say anything else :smile5:

 

[willy fixit]

You're going to have to tell me if you're joking? I don't mind admitting I just don't know if you are or not!!

I don't think I'm going to say anything else :smile5:

Why is the word "gullible" not in the dictionary?

 

[HappyHippyDad]

Had a proper read now! pity.. I really liked that explanation..:dunce2:

 

[baldsparkies]

You're going to have to tell me if you're joking? I don't mind admitting I just don't know if you are or not!!

I don't think I'm going to say anything else :smile5:

Have you ever watched Pearl Harbour ??

The bit where he says I did it to inspire the men sir, because I wanted to be like you.
And the reply is "That's BULL **** !! But its very good bull **** :icon12:

And sometimes it baffles :conehead:

On the other hand when performing mechanical maintenance checks on composite panels and switch gear.
Have you ever noticed its always the neutrals that need tightening up, more so than anything else ??

 

[NickD]

Personally I think the Klingons are to blame here, they're always causing trouble in the neutral zone....

 

[GB.Kayak]

Standard R1+R2 testing on a radial carries out no test on the neutral therefore no poor connection in the neutral will ever be picked up. I'm sceptical about this having any kind of statistically significant part to play though.

You have to bear in mind that on AC, if you ignore potential difference to earth, the neutral spends exactly half of its time being the 'live', really

N, thanks for this ... a really useful and inspirational thought! There is so much focus and emphasis on proving the 'safety' function of an electrical installation that proving the functional aspects of the system has been lost which prevents basic errors being identified on the functional side. 'Useful and inspirational ... ' nay brilliant! I am going to pore over BS 7671 and GN 3 with a new found emphasis!

 

[Resu]

What about burnt neutral and live?

 

[telectrix]

you need to replace the accessory and back box with steel ones, sealing any holes to prevent the spread of fire... oops. it's only CUs that have poor terminations acc. to amdnt.3.

 

[Jonspark]

So if it's down to not giving neutral terminals the same attention/tightening up as lives, why doesn't it show in cu as well as shower switches?

 

[telectrix]

as Trigger (RIP) would have said...... "look after your neutral".