# Which fuses?

#### vincerules

##### Full time elf
I am trying to figure out which fuses to get to fuse all my power injection lines.

I use this 18awg wire for my power injection runs.

I have both 5v and 12v lights so I'll break it down by type:

This is the 5v strip: 30 leds/meter, each strip is 3 meters long. At 7.2w/meter(1.4a) that's ~4.3amps/strip

I am looking at these fuses, they are 250v 5a. I am confused about the 250v part, is that a max voltage? Would these fuses be fine for this?

Next is my 12v:
Strips: 3.2amps/5 meter, but on some runs I power 2 strips. I could use the same fuses about (5a) on the single strip runs and these 10a fuses on the double strip runs.
Rectangle modules: .72w/module. The most I have is 30 in 1 run (21.6w) = 1.8amps. Probably would use the same 5a fuses above.

Does this all check out? I've never dealt with this before.

Thanks for your time and any help/input you can give.

#### ԆцряєсϮ

##### Senior elf
Either way the fuse only needs to be low enough that if a fault occurs causing higher currents then the fuse blows before any thing turns to burny smokey!

#### vincerules

##### Full time elf
ԆцряєсϮ said:
Either way the fuse only needs to be low enough that if a fault occurs causing higher currents then the fuse blows before any thing turns to burny smokey!
Thank you for the reply. So I should be fine just putting 10 amp fuses on every power injection line? Just to have that extra layer of safety.

#### ԆцряєсϮ

##### Senior elf
Should be fine as long as both the cable and whatever is connected can handle 10 Amps

#### damo1271

##### Full time elf
The voltage rating is important once the fuse has blown! The voltage rating determines whether the fuse will actually block current and stop arcing across the blown contacts - in effect continuing the current flow. Therefore a 250v fuse will be suitable for a lower voltage system. There is some theory on AC vs DC voltage ratings but I cant remember.
The 250V should be OK to use. (I use them, not that that means much!)

The current rating should be high enough that they don't blow in normal circumstances - which is plain annoying. On the "positive" side to this, a 1A fuse normally doesn't blow at 1 amp! It will often be more than 1amp.
For the numbers you quote I'd probably look for a 6A or 7.5 amp fuse for a 4A current draw. That gives bit of a buffer with the current (no nuisance blowing) without being to high current and risking melting wires if there is a catastrophic short.

Fuses are better than nothing, but they wont automatically save your equipment (lights or power supplies) if something goes wrong! Fuses are designed to stop wiring from melting (or creating additional light via flames ), not to save your lights.