THAT’S just ridiculously overly-complicated …without some math done beforehand. The ‘lightbulb”….What, exactly, is the “wattage” you recommend? it’s a 12-14 volt system…. why didn’t you specify what you meant?
You did not specify the AMPERAGE of the fuse which is blowing hence I am unable to specify the WATTAGE of the bulb.
My goodness, basic electronics is not rocket science. There is nothing special about using a lightbulb to replace a fuse to troubleshoot problems.
This is how many 12v electronics circuits are troubleshot when a fuse is blowing.
Generally, a fuse amperage is specified approximately 3x of the expected current. (30% rule)
As an example, if it is a 10A fuse which is blowing, 1/3 of that is about 3 amps.
We know
WATTS = AMPS x VOLTS ...hence 3Ax12V=36Watts
Any bulb below 36W would be 'safe' to use.
You need to do your own calculation based on the amperage of the fuse which is blowing.
I keep old 12v bulbs which I replace in my vehicles to use as troubleshooting aids. Simply solder on a couple wires with clips so it is easy to clip to a fuse.
It should go without saying that too HIGH a wattage bulb may not protect the circuit and too LOW an amperage bulb may not allow enough current thru it. (it would be lit all the time...even if circuit is working as expected)
There are other ways to troubleshoot the issue you describe... but the one I have explained above is simple and provides a visual aide (a lit bulb) to help isolate a problem.
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Other troubleshooting methods would include:
- Using an OHMmeter. (resistance) [disconnect battery before using this method]
- Using an AMPmeter (not recommended unless one is VERY aware of electron-flow dynamics)
- Disconnecting things to see the results (may not isolate the problem)
- Guessing (blindly replacing parts hoping it works) [most expensive way to fix something]