Hi, i bought a whole heap of rice for my car and im gonna make like a little switch panel to enable me to turn all the different lighting on and off independantly so im going to run a power line from the battery so its got power all the time but people say use fuses and i was wondering what sort of fuse i'd have to use for this?

I added this link (http://www.x.xstreamhost.com/irr/HTML/gallery/neons.htm) and described with fotos on my site so maybe it will be a bit clearer what im planning to do incase this needs to be known.

You should always install a fuse on any power line that runs directly from the battery. This will protect you from potential fire hazards, and avoid damage to your battery in case of a short in the system.

You can get excellent in line fuse holders designed for this purpose from your local auto accessory store. Get one of the heavy duty ones that accept a blade type fuse.

For effective protection, the fuse should be installed as close as possible to the battery's positive terminal.

To determine the rating of the fuse to be used, you need to establish how much current you will need to draw on this line. (This will also help you to determine the rating of the cable to be used).

Power is expressed as Watts (W), Current is expressed as Amps (A), and voltage is expressed as Volts (V).

Your car runs at around 13.8V when it is running, but we can use a figure of 12v for the purpose of our calculation.

You should be able to read from the package how many watts each of the lights you are going to run is, then total them up to get a total power figure.

Let's say all of the lights together will be drawing a total of 120W (watts).

The formula for power is: VxA=W (voltsXamps=watts)

So therefore, if you have a total of 120W, you can work out the current drain because you also know the voltage (12V).

120 (watts) / 12 (volts) = 10A

So in this case you will be drawing a total of 10A through the line.

I would recommend using 20A cable in this case to allow some flexibility in your power requirements and ensure the cable doesn't overheat.

I would recommend installing around a 15-20A fuse in this example. This will allow some flexibility in your power requirements, and protect you from fires etc, as the fuse will blow if there is a short in the system (ie, if the current going through the fuse is greater than the rated 15A or 20A the fuse would blow. This would very quickly be the case in the event of a short).

I hope some of this helps.

Cheers,

Luke.

myTE, some good information there reaffirming like high school physics (shoulda paid more attention), but a question, say he has the 10a runing through and a 20a cable, what would be the downside to using a 20a fuse? would u lose some power or something? cheers

your neons should already come with a fuse. just use the same size fuse than the one it came with, or if ur running two at a time, maybe a little bit bigger fuse

TRav

myTE, some good information there reaffirming like high school physics (shoulda paid more attention), but a question, say he has the 10a runing through and a 20a cable, what would be the downside to using a 20a fuse? would u lose some power or something? cheers
The fuse should be the weakest part of the system, this is done for safety reasons, you don't want to burn your wires out (and you whole car if it starts in the wrong place) so you have a fuse that breaks if anything shorts! no power will be lost using a smaller fuse but the maximum output will be 10A!

(oh and you've done well myTE... its all good, except for a bit of the labeling... i'll add this in just to save the confusion when you go down to Jaycar/Dicksmith etc, or read the destructions on the neons)

Power (P) is in Watts (W)...
Ampage (I) is given in Amps (A),
Voltage (V) is given in Volts (V),
Resistance (R) is given in ohms (Ω, sometimes R instead)

this gives us... V=IR and P =VI (= V²/R = I²R)

Oh and Nick, by your pics, i'm guess the lights are going on the inside, underneath.... cos its illegal to have them directly visable!

Yeh thats why im also looking to pinch some white elante side skirts so i can hide side neons under there cause theres no room to but them in at the moment, penty of room under the from and back but not the sides and **** you guys have confused me, who lives in brisbane, ill just give you my card and you can go buy everything i need for me haha.

The fuse should be the weakest part of the system, this is done for safety reasons, you don't want to burn your wires out (and you whole car if it starts in the wrong place) so you have a fuse that breaks if anything shorts! no power will be lost using a smaller fuse but the maximum output will be 10A!

(oh and you've done well myTE... its all good, except for a bit of the labeling... i'll add this in just to save the confusion when you go down to Jaycar/Dicksmith etc, or read the destructions on the neons)

Power (P) is in Watts (W)...
Ampage (I) is given in Amps (A),
Voltage (V) is given in Volts (V),
Resistance (R) is given in ohms (?, sometimes R instead)

this gives us... V=IR and P =VI (= V²/R = I²R)

Oh and Nick, by your pics, i'm guess the lights are going on the inside, underneath.... cos its illegal to have them directly visable!

Thanks Dingo, I didn't want to get into VIR etc and Ohms law too much. Just thought I'd keep it to fairly simple Power equations - but of course, you are quite right on the labeling stuff.

Dingo is also right about the fuse being the weakest link. In the hypothetical example, my fuse recommendation would be 15A. This will give you some flexibility over your forecast load, and the fuse will blow before exceeding the cable's rating. A 20A fuse would also work IMHO as the cable will only start to get a little warm if it's rating is exceeded by a small margin, and the 20A fuse will blow before any detrimental condition occurs. Anyway, 15A would be my pick (remembering that's for my hypothetical example and you'll have to perform your own calculations).

Cheers,

:dancin:

Luke.