What sized Fuse is required for added gauges?

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What sized Fuse is required for added gauges?

Unread post by Rambo351 » May 6th, 2018, 11:08 am

Hey guys I have a 2008 triton that I would like to add a volt gauge for.
It is a 12v digital gauge
I want to know what size fuse I should run.

I measured the gauge resistance and came to about 17.3ohms what should I do next ?

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Re: What sized Fuse is required for added gauges?

Unread post by Boots33 » May 8th, 2018, 7:58 am

Ohm's law will give you the equation needed to work out the current draw. The basic formula is Volts divided by Ohms equals Current. So if you work on around 14v that will be 14/17.3 so around 800mA . I would have thought a volt gauge would draw a lot less than that so you may want to check your ohms again 170 Ohms or even higher would seem more likely .

In any case if there is nothing else being connected to the circuit then a fuse of around 2A would be ok and offer
suitable protection. Remember the fuse needs to be as close as possible to the supply connection.

The volt gauge should also be switched with the accessories or ignition circuit to avoid drawing from the battery when the vehicle is not turned on.

V Williamson
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Re: What sized Fuse is required for added gauges?

Unread post by V Williamson » May 11th, 2018, 8:20 pm

Yeah I would have thought that a digital voltmeter would have a lot more impedance than 17.3 ohms - more like several megohms (millions of ohms). Usually the current draw under those circumstances is negligible and almost any small fuse in series would do the job. The fuse would blow in the event of suchlike as a failure in the wiring such as a breach of the cable insulation for whatever reason.

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