Electrical Load for work lights

[crank73]

Electrical gurus. I own a MF GC 2400 and have successfully installed work lights. I tapped into a spare wire behind the seat which was factory connected to a 15 amp fuse. The two work lights I added are each 20 W, are on a switch, are attached to the ROPS, point forward and work like a charm.

Now I want to add a single 35 W light pointing backwards. I want to tap into the circuit I created for the other lights. This rearward facing light will be on its own switch. It doesn't really matter to me if I tap into the line upstream or downstream from the other switch since I will always have my forward facing lights on when I want to use the rearward facing lights.

Either way, my question is, my manual says that the spare power line that my forward facing lights are connected to should be less than 70 W. With each of them being 20 W and my rearward being 35 W, that's 75 W. Using web electrical calculators that would give me 6.5 amps. Why does the book limit it to 70 W if it's on a 15 amp fuse? Is the 70 W a total for all lights on that circuit or is it the largest wattage a single light can be?

Do I need to put this light on its own circuit? Can I safely tap into this line? or should I look for a light with less wattage to keep me under a total of 70W on that line?

Thanks in advance.

 

[Travelover]

Is the wattage limitation based on the alternator size? Otherwise I'd say it is based on wire gauge to prevent noticeable dimming.

 

[crank73]

I was thinking it might be a alternator limitation after I posted. I think I have a 40 amp alternator. Maybe I'll add up the amperage of all lights on the tractor and see what it equals. I assume if I'm less that 40 amps then my alternator should be able to charge the battery.

 

[amigauser]

Do all three lights need to be on at the same time? If not then there is no issue. You could always try it anyway as the fuse should prevent you overtaxing the circuit (if it blows you know there is to much load with all three lights running). You could also go with cheap eBay LED lights for lower wattage.