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Determining Fuse Size.

The question of determining fuse size has been a common one lately so we decided to make a quick write up on choosing the correct fuse size. One common misconception about choosing the correct fuse size is that it’s dependent the load of the circuit. Actually, the load of the circuit should have nothing to do with choosing a fuse size. The fuse size should be based on the SMALLEST wire (largest gage number) in the circuit. Here is how to correctly choose the right fuse size for your circuit.

1) Determine the wire gage you already have by locating it on the package or measuring it.
2) Use the following table to determine the maximum current for whatever wire gage is being used.


Determining the Total Amperage of your Circuit

So you just bought your stuff and are getting ready to plan your installation while USPS gets it to your door. One of the first questions to ask when planning your installation is what size wire to use, which will later determine what fuse to use.

Don't worry if you're lost, you're at Civic forums, we're helpful here.

Current is measured in Amperes, abbreviated to Amps or just the letter A.

1A is equal to 1000mA

. Find the items that you are installing and their current requirements. Add the values and divide by 1000 to get your total current in Amps. You can this use this value in the table above to determine the minimum wire size required.
Here's an example.

Say you bought a cold cathode kit for each side of the dash (2 Transformers), 5 superflux LED's for your vents, and a 4.7" Flexible LED strip for your center console.

If you want to put all of these on a single circuit, you'll need to know the current. Based on the table above, each transformer draws 700mA, each Superflux LED draws 80mA, and the LED strip draws 80mA

If you add up (700*2)+(80*5)+(80*1) you would get 1880mA total.

Divide this by 1000 to come up with 1.88A.

Put 1.88A into the top table in this post. That table tells you that you should have no smaller than 21 gauge wire for your circuit.

Personally I would go with the 20 gauge wire and a 2.5A fuse.



Hopefully this guide helps you install all the products you've bought quickly and most importantly, safely.


Anyone that needs additional information or has specific or more complex installations, please don't hesitate to sign up and search, then feel free to post in the Lighting area if you still have questions.

If I've missed anything or left anything out, please correct me either in this thread or through PM, and I will correct the tables.


Props to the guys at Oznium

 
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very useful info, ive been looking for a chart like this. everyone needs to read this. most importantly, if you wire up something and the fuse keeps blowing, do not ever put a bigger fuse in unless you like starting fire. there is always some wiggle room, since wire standards are sometimes conservative. i used 14 gauge wire and a 15 amp fuse since i didnt want to go 12 gauge which was too big just for hid harness. well the fuse never blew and the wires dont get hot so i think it is safe enough.

 
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wow very nice write up this should help me whn im setting up my bigger sterio on the future..im looking at my current set up and i got 5 gauge wire and they gave me a 150A fuse with it! no wonder my amp almost fried

 
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nice post. wouldve came in handy when i wired my boat. oh well, if it catches fire atleast there will be plenty of water

 
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http://www.crutchfield.com/Learn/lea...uge_chart.html
Theres a more colorful version which also includes length <-- also effects the outcome

 
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nice