Can you help me size the fuse for my new led's?

[fiddlebick]

Spent all Easter afternoon installing my new led accent lighting on the benny. They are the 26" blue or white led strip lights from shoreline marine, purchased at wal mart. I have 5 of these wired in parallel. The package says they are 200ma. I know they draw very little current, but shouldn't I have them fused? Should I fuse the power lead that feeds the switch? And what size fuse should I use..?

 

[cwag911]

I would use a 5 amp fuse and yes, fuse the switch.

 

[kaydano]

Always fuse! You are protecting against an accidental fault that might occur someday in the wiring from causing a fire. Your fuse should be sized no bigger than the current capability of the WIRE you used to hook all this up, and has nothing to do with the size of the lights. You can look up your wire size online. The fuse needs to be as close to the battery as possible, because any section of wire between the battery and the fuse is not protected and can still cause a fire. If you are tapping an existing fused circuit, the reason to fuse the tap is so a short doesn't take out as much stuff. Or, if your tap wire is smaller than your main line, it needs to be fused smaller and match the tap wire. Hope that helps. Ask if you have further questions.

 

[fiddlebick]

Ok Kaydano, here's what I have. I am tapping directly into the hot buss bar under the console to power the switch. I planned on


using 16 gauge automotive wire for that. I assume this section is where the fuse should go, correct? From the switch, I ran 18


gauge 3 conductor thermostat wire to carry the low voltage. I know marine wire is better, but I keep my boat in out of the weather, and pretty much don't go out if rain threatens, so I felt it would be ok. So what size fuse for the 16 gauge tap?

 

[Rockie69]

http://www.oznium.com/forum/topic15761

a quick google search of "what size fuse for the 16 gauge wire" resulted in this information. Looks like 16 gauge wire they would recommend 7 amp fuse. anything smaller would just be you being "more cautious".

 

[kaydano]

I think there's a derate you want to use for the thermostat wire...  Is each conductor insulated individually, then all three are within another outer insulation sheath?  If so, it won't dissipate heat like a regular single 18 gauge wire, and thus the derate.  I have no idea what the new rating would be, but I wouldn't fuse it any bigger than 5 amps, and that might be pushing it.

Assuming the bus bar is fused (it should be from the factory) I would put the fuse right off the bus, then run the wire to the switch.  That way if the switch fails, the fuse will open and your bus bar will still stay hot and everything else will continue to work.

I wouldn't be so worried about weather being a factor in your choice of wire as much as vibration of the boat wearing through the wire insulation wherever the wire is touching something sharp like a metal corner or the tip or threads of a screw.  Not saying the thermostat wire should not be used, just pointing out the decision should be made on vibration and how or where the wire is routed and not so much based on weather.

Hook it all up.  Run the lights for 20 minutes or so, then feel the wire back by the switch (or wherever the wire is carrying the full lighting load).  See how hot it gets.  If it's hot to touch, you should probably change it out with something heavier.

Good luck!