16mm 2 core swa fuse rating

[Invisible-Man]

hi, I am running approx 40m of 16mm 2 core swa, could anyone tell me what maximun size fuse I could or should use as protection via a switchfuse.

Many thanks

 

[Adam_151]

'Gut feeling' says 60A, but you'll have to do the calculations for volt drop and elfi, as well as check the current carrying capacity for the way its installed, BS1361 btw?

 

[Invisible-Man]

Thanks Adam, it will be installed in the ground and under floor boards, it will not have any derating factors that I can think of apart from the length

 

[plugwash]

that really depends, fuses are somewhat harder to calculate for than MCBs and i don't have the tables to hand.

there are 3 issues to consider when selecting a cable size/protective device rating combination

cable rating: this should generally be higher than the rating of the protective device (though there are some exceptions) and higher than the current that is expected to flow in normal use.

short circuit disconnect: you need to get the fault loop impedances (both PN and PE) low enough to ensure that the protective device trips/blows in the required time (5s for a submain or fixed appliance).

volt drop: don't allow more than 10% volt drop total in the run from intake to final load when everything in the path is operating at its maximum expected current (note that the maximum expected current may well be lower than the breaker rating).

 

[ricicle]

Surely you mean 4% Plugwash

 

[plugwash]

oops sorry