size of fuse vs size of wire............. - Off-Road Forums & Discussion Groups
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post #1 of (permalink) Old 09-28-2000, 07:37 AM
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size of fuse vs size of wire.............

i am putting an in-line fuse in a hot wire feed to a relay which opperates an electrical cooling fan.

the fuse has blown twice. i have looked for an obvious short ie bare wire but don't find.

i wonder if my fuse is too small for the size of wire i have or wire too large for fuse.

i don't know the gauge of wire but fuse is 20 amp.

maybe this is too vague![img]/wwwthreads_images/icons/smile.gif[/img]

i'll keep trying![img]/wwwthreads_images/icons/smile.gif[/img]

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post #2 of (permalink) Old 09-28-2000, 08:04 AM
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Re: size of fuse vs size of wire.............

This is Approx.: 18awg 14amps, 16awg 18amps, 14awg 20amps, 12awg 25amps, 10awg 30amps. This also varies according to wire type Insulation and such. A 20amp fuse should be fine for you fan. Does the fuse blown right away? Is the 20 amp fuse feeding the relay? The fan? Just some question that would help.

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post #3 of (permalink) Old 09-28-2000, 10:14 AM
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Re: size of fuse vs size of wire.............

The fuse to the relay voltage should be about 5 amps.

The fuse to the Fan voltage should be about 25 to 30 amps.

Inline fuses come in "quick blow" and "slow-blow" fuses. Slow blow fuses will tollerate a small increase in amperage over their rating for a short amount of time. Quick blow fuses do not. Look to makes sure that the both fuses you are using are slow blow types.

Once installed, if the fan voltage fuse blows again, the fan is drawing way too much amperage and should be replaced. The same problem and solution will exist for the relay fuse.
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post #4 of (permalink) Old 09-28-2000, 01:48 PM
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Re: size of fuse vs size of wire.............

When I put in my fan, I had a problem with the switch that came with it. It worked for a few minutes then the innards got fried and I went throught a whole box of fuses. Then I got out a 12v test light and checked the circuit back to the switch on the dash from the fan. The switch was grounding out the circuit and was the problem, I replaced the switch and now It works fine.

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