Fuse suggestions

I am wiring 30 leds in my jeep, 6 are going to one switch and 24 are going to another switch, what size fuse should I use for each application?

Why not have all of them run using a common power? That way you only need one fuse. As far as the size for that many LED's I would use between a 5A and a 2A depending on the current rating.

1A and a 3A

It depends on what size wire you're using. FUSE TO WIRE SIZE, NOT CIRCUIT LOAD!!!!
http://www.oznium.com/forum/topic15761

Some say, "If you only have a 1/2A load then it MIGHT not blow a 10A fuse if the circuit shorts." These people truely don't know what they are talking about. Here's an example.

Lets say you choose to wire a circuit with 18awg wire. The current capacity is 16A so you decide to choose a safe and common fuse of 15A. Now lets say you have your 15A fuse and 25 LEDs in parallel (25 LEDs at 0.02A is 0.5A) and the LEDs are wired in the back of the car so you have 20' of wire. 18awg wire has a resistance of 0.006385 ohms per foot (total wire resistance is 0.1277 ohms).

Now lets assume that you have a short circuit at the back of the vehicle. Using Ohm's Law, V = I*R. You know voltage is 12V (this is on the low side, more like 14V) and you know resistance is wire resistance of 0.1277 ohms. So, divide voltage (12V) by resistance (0.1277 ohm) and you get a current of just shy of 94A. As you can see, this will blow the correct 15A fuse and the incorrect smaller fuse.

In conclusion, a short will blow a 15A just as easily as it will blow a 1A or 3A fuse.

Except there is absolutely nothing wrong with going with a fuse that is smaller than what the wire can handle.

So, if I have a 50A fuse in a kicker fuse block, will that work for 25 blue LEDs in series on one switch and 5 blue LEDs also in series on another switch?

To me the 50 is WAY TOO BIG ... Go with the 15A as suggested

corvettecrazy wrote:

Except there is absolutely nothing wrong with going with a fuse that is smaller than what the wire can handle.

There's no issue with that if you NEVER change it in the future (if you're going to change it in the future why not do it right the first time and not half ass it?).

Lets say we have the 18awg wire and fuse w/ a 3A fuse b/c we only have 25 LEDs. It's just as safe as a 15A fuse, but no safer (they are essentially equivalent). Now, 1 year later an underbody kit, fog lights, and a bunch more LEDs are added. The fuse blows b/c it's over 3A so the fuse is increased to a 10A fuse. Then awhile later more LEDs are added to make it look like a UFO. The fuse blows again and it's increased to a 20A fuse. NOW YOU HAVE A PROBLEM. Once a fuse is established, it should never be changed unless it's completely rewired.

When you start to change fuses, you end up with potential problems. If you fuse everything the CORRECT way (fuse for wire size) you will NEVER have any safety issues. If the fuse blows from adding too many lights then you know you need new wiring or another circuit.

So, why would you ever fuse for the load instead of fusing based on the wiring? There is NO benifit to choosing a fuse based on the load than choosing a fuse based on the wiring.

The only reason people continue to fuse based on the load is b/c they don't truely understand what they're doing. They were taught it from someone and continue to pass the "knowledge" along to others. Anybody will tell you, just b/c it was done that way in the past doesn't make it the right way to do it.

Jammer wrote:

So, if I have a 50A fuse in a kicker fuse block, will that work for 25 blue LEDs in series on one switch and 5 blue LEDs also in series on another switch?

You can't run 25 LEDs in series alone. You're going to have to have 4 or 5 in series (depending on how much voltage they require) and run sets in parallel. I highly doubt you're going to want to run 8awg wire to all the LEDs either. You're most likely going to want to run something around 18-20 awg wire. If you run 18-20awg wire then you need to fuse it accordingly.

i wasnt going to run 8 gauge all through out it was only going to be to the battery

i wasnt going to run 8 gauge all through out it was only going to be to the battery

Here's everything I ordered, 30 superbright blue 5mm LEDs, 30 plastic LED holders 2ACT fuse holders 10 gauge, 2 5 Amp fuses and 2 blue LED rocker switches. Is there anything else i need to get other that the wire or is that good, like i said im going to wire 25 to one switch then 5 to another then have them go to the battery. ill do 5 in series then connect all of the series together.