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Where to put fuses in a dc circuit? Answered

Say I have a 12 volt battery and I want to connect a light and a radio.  Should I put a fuse next to the positive or negative terminal of the battery?  Or should I fuses in front of everything.  DC current flows from pos to neg right?  so I would put the appropriate fuse on the positive side of each electronic device?    



Best Answer 7 years ago

All my equipment is fused individually on the positive (red) wire.
If you want to fuse the Positive side wire off the battery too its OK.

VOLTAGE FLOWS FROM NEGATIVE TO POSITIVE, AND I JUST USE A 60 AMP FUSE IN A CLEAR COVERED BOX ON THE NEGATIVE SIDE HOOKED UP TO THE BATTERY BEFORE IT (BATTERY) IS GROUNDED TO THE FRAME, SO EVERYTHING I PUT ON THE POSITIVE SIDE IS FUSED UP TO 60 AMPS AND SOMETHING LIKE A RADIO SHOULD BE FUSED WITH A LOWER AMP FUSE WHICH YOU COULD PUT A LOWER AMP FUSE ON THE RADIO ON ETHER SIDE (+) or (-) If You know the amps on everything on it which I don't know what this applies to, You can put in a fuse box to fuse everything on it separate circuits. YOU COULD JUST PUT A 60 AMP FUSE TO GROUND THE NEGATIVE TO THE FRAME, and just a couple lower amp fuses for things like a radio, which can be installed in line on ether side of the item You want to protect from too many amps thus burning it out.

Seconded. It will work on either side, but in series with + is most common.

"current flows from pos to neg right?" -- Depends, current 'technically' flows from - to + (electronis are negative, and they are the part that moves). In the old days it was thought that there was a positive particle that moved so "conventional current" is + to -. These days many schematics use the same old symbols that indicate the direction of conventional current (transistors, diodes, etc) but it's important to understand the difference.

That is good to know man. Thanks for the help I was wandering the same thing, and its working, so I am happy with it.


Tut tut. Are you talking about majority or minority carriers ?Conduction in solid metals is by electron flow sure, but not for a lot of other things.



. Is fusing the positive side a standard (a Q&D search didn't turn anything up) or just convention?

Every fuse I've seen has been on the hot side of AC, or non-ground side of a DC circuit. Probably just convention.

Fuse goes in series with the load, to protect the power supply if the load shorts out. Positive or negative side doesn't matter; fuse responds to excessive current, not voltage or polarity.

In a circuit like this it doesn't matter.