And another mad question ("minimum current")

[Wes1000]

I’ve read your post Richard but surely the very fact it is the current carrying CAPACITY implies a maximum. And the cables capacity must be above that of the protective device.
It just doesn’t work as a minimum?

You take a protective device of current rating C, the minimum current carrying capacity of a live conductor connected to this protective device is C

Surly if a protective device is C then the CCC of cable has to be above C but as for the minimum, it could be anything you want just so long as the protective device will trip before the maximum is reached.

Maybe we are getting at the same thing and I’m missing your meaning? Maybe it’s time for another glass of red. Now where did I put the other bottle.

 

[Deleted member 26818]

Whilst the rating of the protective device should be no greater than the CCC of the cable, the tripping current of the device should also not be greater than 1.45 times the CCC of the cable.

 

[Wes1000]

Too late I’ve opened the 2nd bottle now. This makes no sense any more.

 

[Richard Burns]

The current carrying capacity of the cable must be greater than or equal to C, e.g. if C is 10 then CCC could be 10, 20, 540, 2340. However the minimum value is 10. It cannot be lower than this.

 

[rich3009]

Ohhh I see so by minimum they are talking what's the minimum that will do the job, the wording is bad it should say calculate the minimum required capacity live conductor current for the circuit.

 

[Wes1000]

The current carrying capacity of the cable must be greater than or equal to C, e.g. if C is 10 then CCC could be 10, 20, 540, 2340. However the minimum value is 10. It cannot be lower than this.

Yes, on a sober mind this morning it all becomes clear. I completely agree.

 

[Wes1000]

@Amp David why do you disagree? You need to know the size of protective device so you can select a cable that will carry a current capable of tripping the device safely if your going to design a circuit.