Fog Lights

[NancysToy]

If the manufacturer included a 15 amp fuse, I would guess that the fog lights need to be fused at 15 amps to work reliably. If you are scaling back to 35 watt lights, the 10 amp fuse should work without any issues.

My experience with these indicates that there is a lot of variation by manufacturers in selecting fuse and wire size. Some cut it close, and some go the extra mile. Most fusing seems to be based on wire size, and not necessarily the load involved. If this manufacturer used a 15 amp fuse and correspondingly heavier wire for a 10 amp load, that is good.

These types of lights are usually prone to substantial heating while in use. That reduces the circuit's ability to carry the load, so heavier wiring and fusing may also be adviseable from that standpoint. A 10 amp fuse would leave insufficient margin with a 9.2 amp cold load. At any rate, don't increase the rating of the Spyder fuse without verifying that the wire size is adequate for a larger load. I would also advise against wiring straight to the fusebox with a 15 amp fuse there, since that leaves the remaining, standard harness inadequately protected. Better to install an auxilliary fusebox and ground bus, or the Evoluzuion power block, and tap in there. Best advice, switch to 35 W bulbs. It will simplify your life.
-Scotty

 

[BRPjunkie]

Thanks everyone for your input.

 

[Spanky]

I deal with this type of specmanship every day.

A 10 amp fuse for 9.2 amps load is not the ideal condition. The is no headroom for surges. Everyone is saying 55 Watts at 12 volts. That is the rating of the lamps at 12 volts and that wattage will increase as voltage increases. These things magneto will put out anywhere from 13 to 14.5 volts. Then voila you are over 10 amps.

In this case I would put a minimum of a 12 amp fuse and I would be very comfortable at a 15 amp fuse. It is not an unusual to to fuse at 150% of rated load.

I hope this helps....

 

[pphantom538]

Scotty & Spanky,
Thanks for the advise.

 

[SpyderMark]

The 55 watt lights I bought have an in line 15 amp fuse, that's why I thought it might need a 15 at the fuse block.

The fuse is there to protect the wiring, not the component. If the component (or any other part of the power circuit) shorts to ground, you want the fuse to blow BEFORE the wire burns.

Current handling (amperage) of the wire is based on its size (gauge), and whether or not it's part of a bundle. Send a current thru a wire and it begins to heat. For a given gauge wire, the more current, the more heat. A wire in free air can handle more current than a wire that's part of a bundle because it can radiate the heat away.

Bottom line; if the wire as installed in the circuit can handle 35 amps at 14 volts without burning, a 30 amp fuse is perfectly acceptable -- even if the component connected to the circuit only draws 2 amps. Conversely, if you install a 30 amp fuse to "protect" a component which draws only 20 amps, but the wire can only handle 25 amps, the wire will smoke before the fuse blows.:shocked:

Letting the smoke out of a wire (or other electrical/electronic component) renders it inoperable. Also, once you let the smoke out, it's nigh impossible to get it back in...

The wire that comes with most aftermarket light kits is typically hardy. Since the fuse in the inline holder that comes with such kits is designed to protect the wiring, one might make the assumption the kit manufacturer appropriately sized the inline fuse, but you can check for yourself.

Click here for an excellent thread on wire size and fuse selection.

Regards,

Mark

 

[ataDude]

...Letting the smoke out of a wire (or other electrical/electronic component) renders it inoperable. Also, once you let the smoke out, it's nigh impossible to get it back in...

Mark

Bahawaaaaa!

 

[bjt]

The fuse is there to protect the wiring, not the component. If the component (or any other part of the power circuit) shorts to ground, you want the fuse to blow BEFORE the wire burns.

Current handling (amperage) of the wire is based on its size (gauge), and whether or not it's part of a bundle. Send a current thru a wire and it begins to heat. For a given gauge wire, the more current, the more heat. A wire in free air can handle more current than a wire that's part of a bundle because it can radiate the heat away.

Bottom line; if the wire as installed in the circuit can handle 35 amps at 14 volts without burning, a 30 amp fuse is perfectly acceptable -- even if the component connected to the circuit only draws 2 amps. Conversely, if you install a 30 amp fuse to "protect" a component which draws only 20 amps, but the wire can only handle 25 amps, the wire will smoke before the fuse blows.:shocked:

Letting the smoke out of a wire (or other electrical/electronic component) renders it inoperable. Also, once you let the smoke out, it's nigh impossible to get it back in...

The wire that comes with most aftermarket light kits is typically hardy. Since the fuse in the inline holder that comes with such kits is designed to protect the wiring, one might make the assumption the kit manufacturer appropriately sized the inline fuse, but you can check for yourself.

Click here for an excellent thread on wire size and fuse selection.

Regards,

Mark

This has turned into an electrical design thread...

 

[retread]

Wow, reminds me of trade school days.opcorn: