Fuse in 5 volt charging circuit?

[BabaYaga]

I use a 50W DC-DC converter to supply a few USB sockets used for 5 volt charging of phones etc.
The 12 volt feed to the converter is fused at 5A (I think), but is it essential to also have fuses in the 5V circuits? There are none right now.
If there was a short somewhere in the 5 volt wiring, would the converter be damaged before the fuse blew? Is there a fire risk?
The 5 volt wiring is 0,75mm sq and the distances quite short, less than 1 metre. Maximum current draw in each circuit is a little over 2A. The converter can supply maximum 10A@5V.
I would be grateful for any input.

 

[William_H]

One would expect that the converter would shut down or at least limit the output current to 10 amps or just fail in the case of a short on the 5v lines. So assuming the 0.75mmsq wire can carry 10 amps without incandescing (smoking) then you must be safe. Perhaps unlikely. You might also consider where these light wires lay if they do get very hot. ie can it set fire to upholstery etc. If there is a concern then a 2 or 3 amp fuse in each 5v line might be in order. Presumably it would not be convenient to use heavier wire to the 5v device. So they are the considerations to help you make the decision. good luck olewill

 

[BabaYaga]

One would expect that the converter would shut down or at least limit the output current to 10 amps or just fail in the case of a short on the 5v lines. So assuming the 0.75mmsq wire can carry 10 amps without incandescing (smoking) then you must be safe. Perhaps unlikely. You might also consider where these light wires lay if they do get very hot. ie can it set fire to upholstery etc. If there is a concern then a 2 or 3 amp fuse in each 5v line might be in order. Presumably it would not be convenient to use heavier wire to the 5v device. So they are the considerations to help you make the decision. good luck olewill

Thanks! Wire 0,65mmsq (AWG 19) seems to take a maximum current of 14A if I read the tables correctly. So in case of a short in a 5V circuit I reckon I would be protected by the converter shutting down, failing or, if not, by the 5A fuse in the 12V supply to the converter. Hopefully.

 

[VicS]

Thanks! Wire 0,65mmsq (AWG 19) seems to take a maximum current of 14A if I read the tables correctly. So in case of a short in a 5V circuit I reckon I would be protected by the converter shutting down, failing or, if not, by the 5A fuse in the 12V supply to the converter. Hopefully.

There are numerous tables of current rating vs wire x-section. The rating depends on various factors.

0.75mm² is the x-sectional area of 6 amp domestic flex .

14 amps ITYWF is the absolute maximum and is for for single conductors in free air.