What size Fuse is best?

[patrolcarr]

I just had a minor problem with my deck lights. Basically they didnt go on when I flipped the switch, and through a little trial and error found that the fuse that regulated the lights was missing. I had some work done on my boat(19ft 1981 Grady-White) and the fuse probably just fell out or wasnt replaced during routine maintanance. My question is this: If I'm not sure what size fuse to use, should I go a little heavier or a little lighter? Although my electics arent marked well, they are actually well installed, but Im no no electrician. Are there standard size marine fuses I should have on board at all times? I just happened to have a few fuses on board from the previous owner but should probably get more. Any advice on these minor things? Thanks

 

[Squirt]

Re: What size Fuse is best?

If you can figure out how many "amps" each light pulls (ussually written on the back) add up all these "amps" and put a fuse in that size. example:4 lights at 1.2 amps each=4.8 amps so I would put a 5 amp fuse in.This is in no way advice on what"you" should to dnly a suggestion, you may check with a certified electrician for further info. Hope this helps. Squirt

 

[Xcusme]

Re: What size Fuse is best?

Squirt has good information but here's some more info for ya.<br /><br />After determining the total current draw ( Squirts post ) the next most important thing to know is the size of the wire that connects everything together. Wire is rated by how many amps it can carry. The wire can have solid conductors or it can have a lot lot of smaller wires called 'stranded' wire. Stranded wire can carry more amps and is usually the type of wire used. The important thing to remember is, don't install a fuse that exceedes the current carrying capacity of the wire you are using. <br /><br />Here's an example:<br /><br />12 lamps drawing 1 amp each. The logic follows that the fuse should be a little above that , say 15 amps. With the PROPER SIZE WIRE feeding all of the circuits, things will be fine, the wire can safely carry the total current draw for all of the lights.<br /><br />Now say you add 10 more 1 amp lights, the total current draw will be 22 amps. This will blow a 15 amp for sure. If you replace the 15 amp fuse with a 25 amp fuse, the lights will light BUT, the wire may not be big enough to carry the additional amperage and the wire will start to get hot and possibly melt the insulation and start a fire.<br /><br />The fuse is there to protect the circuit from overloads (too much current) . The fuse protects the wires. Never 'over fuse' a circuit based solely on the load ( how many lights you have) you must consider the current carrying capacity of the wires as well.