Overloaded cable, or not ?

Whilst retro fitting a rcbo i spotted this cable. Its feeding a kitchen ring but only a dish washer and occasional sockets. 

The ring tested out fine, low value  end to ends etc.  Only 1 cable has overheated, i recon it was loose or even had missed the cage in the breaker. Whats everyone elses view.

Also, the breaker had thermal damage so that was swapped out.

The double tails stuffed in the main switch are nothing to do with me, i just didnt fancy  peeling that tape off to even have a peek. I was working on a different circuit. 

where is the damage? if its limited to just the first few inch then id say loose connection. if its throughout then overload

Right.....

have a look at this blow up

the OK cable is bent over and has the end running N-S

tye melted cable has the end running 'flat'. I.e. E-W

if the cage is slightly curved then the ok cable will have tightened and the melted one will be loose

of,course this would NEVER have happened if a torque driver had been used

And that concludes the evidence for the prosecution

Perfect demonstration of why you should never double back the cable if there is more than one cable in the connector.  Straight cut cable ends would have avoided the problem.

Some MCBs  seem to be notorious for NOT catching all the cores in the box terminal ,  Crabtree  I think , is one of them .        Three 2.5s  specially vulnerable ...one is always loose until you've checked them 500 times . 

I think, M'lud  that my learned colleague  for the prosecution is correct in his summing up . 

kerching said:

Right.....

have a look at this blow up

the OK cable is bent over and has the end running N-S

tye melted cable has the end running 'flat'. I.e. E-W

if the cage is slightly curved then the ok cable will have tightened and the melted one will be loose

of,course this would NEVER have happened if a torque driver had been used

View attachment 9421

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Well spotted. I took that pic holding the camera over my head as the board was near the ceiling and my steps wern't tall enough

Probably a standard tug test would have found that fault though.

Damage already done and cable welded in, first thing after turning off  was to give them a tug and they didnt budge even giving a yank with pliers.

probably been like that for years and now working fine, not sure I would leave it though - last one in and all that...

I've always had a theroy old electrics have welded the contacts together, I find old houses tend to test-out better than newer houses, but that might be something to do with quality slipping.

Don't worry men, Metal enclosures solve all of these problems!

Doc H.

Doc Hudson said:

Don't worry men, Metal enclosures solve all of these problems!

Doc H.

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And Torque drivers

dont forget about Torque drivers

How did I manage without a torque driver   :C    Dunno but I still do  

BTW, Its been fixed. It was fine last time i worked at that board about 2 years ago.

Evans Electric said:

How did I manage without a torque driver   :C    Dunno but I still do  

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I must get my wrist recalibrated.

The only time I’ve torqued up anything was on vibrating feeders, 600 Ft Lb takes some doing even with a 4 to 1 torque multiplier.

I think ,  as we've said before ,  a few basics seem to be lacking these days .   

A couple of basic things with consumer units .     ( For  newbies to the trade )           

Fix to a flat surface or they'll distort and you struggle to get the cover on . 

Double check those "hard a iron"  meter tails in the box terminals  after bending & twisting them.

Count off the bus bar terminal screws  to be tightened & make sure all the "fingers" are in the boxes. 

Make sure you tighten up   ALL  the terminals  with a (+) (-)  screwdriver .    

As said above ....give 'em a tug when finished  specially 2.5 solid cores .   

And a personal  idiosyncrasy .....    some boards have bare bus bars ...insulate them with some tape .   

Evans Electric said:

And a personal  idiosyncrasy .....    some boards have bare bus bars ...insulate them with some tape .   

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I do that, even when behind the slot in plastic cover. Also, Wylex for one say to use a P2 driver for all terminals.

SLIPSHOD & SLAPDASH said:

Also, Wylex for one say to use a P2 driver for all terminals

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I  mean those ones ...the name of which always escapes me  .... Modulo   :C     half Phillips -half normal   .. I call them mad drivers . 

All the ones I buy  have snapped off   ...just one  left  seems to be tempered properly .     Phillips  / Pozi   usually work as well TBH.  

Evans Electric said:

I  mean those ones ...the name of which always escapes me  .... Modulo   :C     half Phillips -half normal   .. I call them mad drivers . 

All the ones I buy  have snapped off   ...just one  left  seems to be tempered properly .     Phillips  / Pozi   usually work as well TBH.  

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I,connected a cooker up for a mate a few months ago...........it needed 4 different screwdrivers!!!!!!!!!! WTAF is going on

flip,off cable cover.....flathead

cable clamp................torx

L-N...............................6mm hex

earth.............................5mm Hex

luckily all are in my WIHA interchangeable set but WTAF!