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TexasFire
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156 Posts
Discussion Starter · #1 ·
There may be a more suitable forum for this question but it has to do with lights on a '68 Ford 2000. I have bought a pair of 55 watt headlights & a 35 watt rear work light. I have 20A capable switches for both. My question is what is the appropriate size fuse for each of these loads?

TexasFire :thanku:
 

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The Magnificent
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20,952 Posts
55 watts divided by 12 volts equals 4.58 amps. You need to allow for a surge of about 10 percent, so .4 amps plus the 4.58 means a 5 amp fuse should be good for each 55 watt light. But since you no doubt will run the two front lights from a single switch then a 10 amp would be fine, and you could go to a 15 or 20 (the max capacity of the switch). DO NOT OVERFUSE AND USE THE PROPER SIZED WIRE FOR THE LOAD.

Use the same formula to calculate the load of your rear work light.

Now for the $64 question - where exactly will you be getting the power for the switches?
- Straight off the battery? (bad idea and you can accidentally leave them on when you turn off the tractor.
- Straight off the ignition switch? (real bad idea as the ignition switch isn't built for that kind of continuous current)
- Via a relay (the best idea is the relay is picked by the switch, which is in turn powered by the ignition switch. The relay then switches current to the lights directly from the battery).
 

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1981 Ford 1100 4WD
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880 Posts
If you go the relay route (which is a good idea) then you can take power for the relay coil from the ON position of the ignition switch. So when the switch is OFF so are the lights, regardless of the light switch. Then take the relay contact through a fuse and the light switch to the battery.
 

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TexasFire
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156 Posts
Discussion Starter · #5 ·
I'm feeling kinda lazy so I'll probably skip the light relays. My ignition switch DOES have an aux tab I could power them from. Using the formula you provided I plan to use a 5 amp fuse on the work light & a 10 amp fuse on the headlights. I will wire to the battery, both of my switches are lighted switches so I'll have an extra reminder that a switch is on, but don't expect I'll be accidentally leaving them on. The local parts house has aux light relays for $6 so it wouldn't cost much to add them. Maybe somewhere down the road.... I plan to use 16 gauge primary wire to the red / hot wire on each light & ground the black wire. Looking forward to having lights!!!!

TexasFire

:thanku:
 

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TexasFire
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156 Posts
Discussion Starter · #7 ·
Sorry, I stated that wrong, I would power the light relay (if I choose to run one) from the aux tab on the switch. I have no idea what its rated for, but its a brand new aftermarket switch that I picked up from Steiners that has an on - start - aux position.

TexasFire
 

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The Magnificent
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20,952 Posts
Sorry, I stated that wrong, I would power the light relay (if I choose to run one) from the aux tab on the switch. I have no idea what its rated for, but its a brand new aftermarket switch that I picked up from Steiners that has an on - start - aux position.

TexasFire
Nope, my fault. You did say you will wire straight from the battery.
 

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TexasFire
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156 Posts
Discussion Starter · #9 ·
OK, this probably sounds silly but I'm wondering what is the best way to run the wire from my work light on the rear fender to the steering cowling where my switch is. There's no body channel & I need to steer clear of the exhaust. Should I use those self-stick wire holders & just run it down the side of the transmission? There's an old wire pigtail hanging out of the old tail light fixture (light long gone) but no sign of how it was attached...

TexasFire
 

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1981 Ford 1100 4WD
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880 Posts
I worked on a 71-2000 and it had a steel tube that ran down the left side of the transmission. ending back by the rear axle housing. This is where they ran the wire for the flasher that was on the left fender.
 

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TexasFire
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156 Posts
Discussion Starter · #11 ·
Thanks Don, someone else told me about the tubing thing too.... May need to go look at some examples to see how they were attached....

TexasFire
 

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TexasFire
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156 Posts
Discussion Starter · #12 ·
OK.... Back again, I think I have this right but wanted some extra opinions! As I have posted I am installing 12 VDC headlights & I plan to used a lighted 30A switch. Obviously the switch needs a ground (it has a plastic case) so the light can come on when the switch is closed. The only wiring diagram is very small on the back of the switch. There are two opposing tabs on top & bottom of the switch & then a center tab that sticks up higher than the other 2. If I am interpreting this correctly, the 12V+ power comes in on the bottom tab, the ground is on the opposing tab & the load, or 12V+ that goes to the light hot wire when the switch is closed or "on" comes from the middle. I will probably do a test wire prior to installation before I commit to rigging it all up. Thanks for any input!

TexasFire
 

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OK, this probably sounds silly but I'm wondering what is the best way to run the wire from my work light on the rear fender to the steering cowling where my switch is. There's no body channel & I need to steer clear of the exhaust. Should I use those self-stick wire holders & just run it down the side of the transmission? There's an old wire pigtail hanging out of the old tail light fixture (light long gone) but no sign of how it was attached...

TexasFire
Greetings sir . If your looking for a simple , neat & durable solution then I would suggest using some 1/4 or 3/8 diameter steel brake lines . There are various lengths available & many have coatings to prevent premature rust . Just bend them to the shape & contours you need and attach them with whatever means thats suitable then you dont have to worry about snagging the wires with anything . The flared ends of the lines provide a smooth radius and prevents chaffing of the wires , I just cut the nuts of or grind the off .

Mike
 

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1981 Ford 1100 4WD
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880 Posts
great idea on the brake lines ! And remember, you only need to run the HOT wires not ground.
 
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