Overloaded cable, or not ?

[SLIPSHOD & SLAPDASH]

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.

 

[SLIPSHOD & SLAPDASH]

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. 

 

[Andy™]

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

 

[kerching]

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

 

[kerching]

And that concludes the evidence for the prosecution

 

[sparky308]

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.

 

[Evans Electric]

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 . 

 

[SLIPSHOD & SLAPDASH]

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

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

 

[roys]

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

 

[SLIPSHOD & SLAPDASH]

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.

 

[binky]

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.

 

[Doc Hudson]

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

Doc H.

 

[kerching]

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

Doc H.

And Torque drivers

dont forget about Torque drivers

 

[Evans Electric]

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

 

[SLIPSHOD & SLAPDASH]

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

 

[Tony S]

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

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.

 

[Evans Electric]

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 .   

 

[SLIPSHOD & SLAPDASH]

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

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

 

[Evans Electric]

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

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.  

 

[kerching]

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.  

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!