Where to put fuses?

Hi Everyone,
I working on a project. There is external wiring and there is a chance the wiring could get cut, i would like to know if my locations of fuses is correct, or if there are any other spots I'm missing. Could you please take a look at the below diagram and let me know if i'm on the right track. Also, any help with fuse sizing would be awesome.

The goal of the project is to have 2x 5 way switches, each switch can control the behavior of some attached LED's that are being driven by a BlinkM Max M board via I2c. The LED's are connected with some decent cable (4 conductor industrial wiring cable) but they can be plugged and unplugged while the system is 'on' is this bad for the drivers? Are the drivers protected against a dead short (in case the cable gets cut?)

(the drawing is partially cut, but the only piece missing is 2 more drivers, so other wiring gack)

Cheers.
jon

What is the difference between "Fuse Supply" and "V+"? In the upper right-hand corner you have fuses pointing to lines. What are those?

Fuses should be placed anywhere short circuits could result in Death or significant circuit damage.

okay cool, that's what i thought. there isn't a risk of significant injury as all upstream power is protected by gfci's that are setup by people that know more than me. (this post is more related to protecting the circuits, than people, as giving advice on human protection opens a giant can of worms... which is not what asking about)

the arrow's are pointing to the lines asking if these lines need to be fused, as all the other lines are in the 5v range, at low mill-amp. the biggest question, the LED drivers are inside a control box, and the LED's are outside the box. How do i protect the drivers in event the cabling gets cut? each LED strip can pull 1.2 amps, from what i've read the fuse should be about the same voltage, but at 115% of the amperage rating. is this correct?

thanks
Jon

from what i've read the fuse should be about the same voltage, but at 115% of the amperage rating. is this correct?

No.

Fuses do not have a voltage rating.

The fuse should have a slightly higher rating than the expected current. However it is much more complex than this. You have to consider surge conditions and the speed of fuses blowing. It is much better to to use the current limiting circuit of the power supply that use a fuse on low voltages. You have to ask what are you protecting, most of the time a semiconductor is a device that will blow very quickly thus protecting the fuse.

Fuses do not have a voltage rating.

Well they actually do, but it's not the only specification one uses to select a proper fuse for a specific application.

Lefty

Fuse holders have voltage ratings, the fuses themselves do not.

Grumpy_Mike:
Fuse holders have voltage ratings, the fuses themselves do not.

I beg to differ. All fuses have a maximum working voltage rating.

Lefty

very good info guys, i will look into current limiting supplies, just to learn a bit. but it looks like there arent going to be very many fuses in this project. as i totally understand that the "semiconductor will protect the fuse" and relativly speaking the parts are cheap.

are there other ways of protecting circuits from wiring faults? i have very little 'theory' knowledge in this area. i'm learning as i go.

cheers-
Jon

are there other ways of protecting circuits from wiring faults?

It depends on what sort of circuit you want to protect and from what sort of faults.

Basically no, there is no way of 100% protection from a wiring fault.

If you have a power supply then an over current and/or over voltage protection circuit can be made to shut down the supply. However, while this can happen very fast you walk a fine line between what will damage a component and what you might want it to do normally.

For example no amount of protection circuitry is going to prevent a transistor blowing up if you have no current limiting in the base.