# Twin and Earth



## RIVETER (Sep 26, 2009)

meadow said:


> What is the ampacity of 1.5, 2.5 and 4mm2 twin and earth?


 6.35 amps


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## Meadow (Jan 14, 2011)

RIVETER said:


> 6.35 amps


:laughing:

Ill just put it on what ever looks good then:whistling2::laughing::jester:


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## chewy (May 9, 2010)

IIRC 2.5 is good for 20A.


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## Aussielec (Apr 1, 2012)

It would really depend on the derating factors applied to the cable and the maximum temperature rating of the insulation.

V90 cable (maximum temperature rating of the cable insulation) hanging in the air will get you around 20amps for 1.5mm, 25amps for 2.5mm and 32 amps for 4mm.


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## Meadow (Jan 14, 2011)

Aussielec said:


> It would really depend on the derating factors applied to the cable and the maximum temperature rating of the insulation.
> 
> V90 cable (maximum temperature rating of the cable insulation) hanging in the air will get you around 20amps for 1.5mm, 25amps for 2.5mm and 32 amps for 4mm.


Good so far. When T&E is in wall, what would be the de-rated current rating?


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## chewy (May 9, 2010)

meadow said:


> Good so far. When T&E is in wall, what would be the de-rated current rating?


There is a table we use that has its ratings for 60 degrees celcius, Ill see if I can dig it up.


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## Meadow (Jan 14, 2011)

chewy said:


> There is a table we use that has its ratings for 60 degrees celcius, Ill see if I can dig it up.


That's what I need


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## Pharon (Jan 20, 2014)

This might help - says it's referenced from the BS7671 17th edition:

http://www.lightwiring.co.uk/lighti...-cables/twin-and-earth-cable-current-ratings/


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## Meadow (Jan 14, 2011)

Pharon said:


> This might help - says it's referenced from the BS7671 17th edition:
> 
> http://www.lightwiring.co.uk/lighti...-cables/twin-and-earth-cable-current-ratings/


The thing about the table is it doesn't mention the OCPD requirements. Ie, if a non standard sixe comes up do you round up or down?


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## Pharon (Jan 20, 2014)

I'm not that familiar with how Limeys do it across the pond - where are you working right now that you need to know all this?


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## Meadow (Jan 14, 2011)

Pharon said:


> I'm not that familiar with how Limeys do it across the pond - where are you working right now that you need to know all this?


Its top secret :laughing::jester:


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## TOOL_5150 (Aug 27, 2007)

RIVETER said:


> 6.35 amps


are those metric amps?


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## Shock-Therapy (Oct 4, 2013)

Sounds like drunken ramblings.


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## chewy (May 9, 2010)




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## Meadow (Jan 14, 2011)

IS this table relevant to all installations or are those ampacities just for wire clipped to the surface of the wall?


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## Meadow (Jan 14, 2011)

So its safe to run 20amps on 2.5mm2 twin and earth when within a wall cavity?


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