Domestic CUs have built in wiring of 16mm2 but...

[Eddiesparks]

...what if you had a 100a cutout?!

So for e.g your tails (consumer and dist.) are both 25mm2 and you have a cutout fuse that is 100a - technically the cutout fuse is the only thing protecting from itself to the bottom of your mcbs. Most consumer units have the "built in" cables that are 16mm2 (from bottom of main switch to top of RCDs) - The CCC of these cables is 85/87ish amps so isnt that a problem?!

I'm curious!

Thanks

Ed

 

[ian.settle1]

...what if you had a 100a cutout?!

So for e.g your tails (consumer and dist.) are both 25mm2 and you have a cutout fuse that is 100a - technically the cutout fuse is the only thing protecting from itself to the bottom of your mcbs. Most consumer units have the "built in" cables that are 16mm2 (from bottom of main switch to top of RCDs) - The CCC of these cables is 85/87ish amps so isnt that a problem?!

I'm curious!

Thanks

Ed

And the question is?

 

[telectrix]

the CU tails are tri-rated and will withstand higher currents than the same csa of 7 strand, notwithstanding that they may have a higher max. temperature, which should be limited to the temp. rating of the main switch/RCD/s etc.

 

[Eddiesparks]

The 16mm2 cable would fail before the 100a fuse. ISNT THAT A PROBLEM AND WHY ISNT IT IF IT ISNT?!?!

 

[DNS1]

I asked this exact question a few weeks back...

as Telectrix says, the internal cables in a CU are not standard tails.

 

[Eddiesparks]

Ok, having a stab it's conductors in parallel as load is balanced from both rcd protected sides. Am i right?!

 

[Eddiesparks]

Ok just read your posts. Thanks all!!

 

[GLENNSPARK]

...what if you had a 100a cutout?!

So for e.g your tails (consumer and dist.) are both 25mm2 and you have a cutout fuse that is 100a - technically the cutout fuse is the only thing protecting from itself to the bottom of your mcbs. Most consumer units have the "built in" cables that are 16mm2 (from bottom of main switch to top of RCDs) - The CCC of these cables is 85/87ish amps so isnt that a problem?!

I'm curious!

Thanks

Ed

oh man!!
lol...lol...
what happens to current in parallel circuits eh eddie?

 

[Darkwood]

Your forgetting that their are normally doubled up sets, one set to each of the RCD units thus the load is shared down 2 sets of 16mm... as above the cable is tri-rated and unless you know the manufacturer then you cant gage its rating which well come down to 3 factors
-Core arrangement
-Size
-insulation

 

[Eddiesparks]

Can you buy the tri rated cu tails without buying a CU? Daft question i know

 

[Richard Burns]

Can you buy the tri rated cu tails without buying a CU? Daft question i know

https://www.electric-cable.com/tri-rated-cable.php

 

[Darkwood]

As above any wholesalers will supply it but its use may have restrictions like panel wiring etc as its insulation has differing properties...

 

[Eddiesparks]

Thanks i will 'tri' and get some

Groan...

 

[telectrix]

have used tri-rated for meter tails in the past (coz. it was free from where i worked). bear in mind you need to fit crimps to the ends.

 

[Engineer54]

...what if you had a 100a cutout?!

So for e.g your tails (consumer and dist.) are both 25mm2 and you have a cutout fuse that is 100a - technically the cutout fuse is the only thing protecting from itself to the bottom of your mcbs. Most consumer units have the "built in" cables that are 16mm2 (from bottom of main switch to top of RCDs) - The CCC of these cables is 85/87ish amps so isnt that a problem?!

I'm curious!

Thanks

Ed

I wouldn't worry your head about it, not just because of the internal configuration of dual RCD CU's, but the fact you'll probably never see 100A being drawn through a typical domestic/commercial CU. ...I know that i never have, and not even close either!! lol!!

 

[Amp David]

Ok just read your posts. Thanks all!!

Ha Ha, it does help sometimes