Driving Lights from Walmart

[cactusjack]

Originally Posted by OP

Got to avoid the snakes and roadrunners right?

Well, that and coyotes and javelinas, too.

[rksaw]

Don't forget those Arizona Alligators. Looks good CJ!
Rich

[michiganmike]

If you are blowing a fuse when the lamps are on then you have a high resistance ground someplace after the switch. More than likely you pinched a wire and a small part of the copper under the insulation is touching a grounded part of the bike.
As for putting a larger size fuse in, it was stated correctly that a fuse is used to protect the wiring, not the appliance. What I would question is the wire gauge given for an amp rating. Standard wire size for a 20 amp circuit is 12 gauge. This is for a 120 volt circuit, but it is also considered by many to hold true for 12 volt circuits. You will also find places where they consider using 14 or 16 gauge wire for a 20 amp circuit in an automotive circuit acceptable.

Here is a web site from a custom car site that gives what they believe to be correct wire sizes for amp ratings when used in an automotive circuit.

http://www.customrodder.com/tech/060.../photo_09.html

[moenko]

Mike, the reason for a higher Amp fuse is simple: On average, more Amperes flow in a 12-Volt circuit than in a 110 Volt circuit.

Remember: Amps = Watts divided by Volts

Althought the battery will provide around 13 Volts, it's prudent to use the 12 Volts for calculation purposes:

110 Watt lights divided by 12 Volts = 9.2 Amperes (steadily flowing, not peak!!!!!)

Will a 10 Amp fuse be okay? Sure, but it's too close for comfort to me. Here's the 12-Volt / wire / fuse chart that has been in circulation for a long time and is - IMHO - accurate:



The Stebel horn, for example, comes with 16 Gauge wire and recommends a 20 Amps fuse... Right On !!!! ;)

Originally Posted by michiganmike

If you are blowing a fuse when the lamps are on then you have a high resistance ground someplace after the switch. More than likely you pinched a wire and a small part of the copper under the insulation is touching a grounded part of the bike.
As for putting a larger size fuse in, it was stated correctly that a fuse is used to protect the wiring, not the appliance. What I would question is the wire gauge given for an amp rating. Standard wire size for a 20 amp circuit is 12 gauge. This is for a 120 volt circuit, but it is also considered by many to hold true for 12 volt circuits. You will also find places where they consider using 14 or 16 gauge wire for a 20 amp circuit in an automotive circuit acceptable.

Here is a web site from a custom car site that gives what they believe to be correct wire sizes for amp ratings when used in an automotive circuit.

http://www.customrodder.com/tech/060.../photo_09.html

[MikeInFla]

Thanks for the help everyone.

I am using 16 gauge wire and I will move the fuse up to something close to 14 or 15.

I'm going to wait for the weekend to look at it again, but I think I will take all the wires off and verify nothing is touching or shorting out. All my connections are soldered and shrinked just to make sure I have a good connection.

I'll let you know what I find.

[michiganmike]

The rule in wiring is if you have a 20 amp circuit, you only run a maximum of 16 amps of current through the wiring. This works out to 80% of the rating of the fuse. The wiring still has to be rated to carry 20 amps. If your circuit for the lights draws 9.2 amps, you do not want to use a 10 amp fuse. For that circuit you want to have a 12 amp fuse. But you still want to use a gauge of wire that is rated to carry 12 amps. In industrial or house wiring, this would be a 14 or 16 gauge wire. What the rules are for automotive wiring I do not know. If I remember I will ask the mechanics at work if they have a chart or can tell me what gauge wire they use for their work.

[moenko]

Mike, in residential wiring you mainly use:

AWG 14 - with 15 Amp fuse
AWG 12 - with 20 Amp fuse
AWG 10 - with 30 Amp fuse
AWG 8 - with 50 Amp fuse

But that's in a 110V (120V) circuit. Stranded (automotive) wire comes only in the gauges mentioned in the chart. You are absolutely correct, however, that you want to restrict the actual Amperage to 80% of the wire capacity at CONTINUOUS flow (as in the lights) and fuse that wire correctly to protect it from overheating. You can trust me on the chart above, bud! I don't know squad about engines, but electricity and math are not foreign to me ;)

SlowMo: AWG 16 is perfect and you can use a 15 or 20 Amp fuse and your wires will be fully protected AND the lights will not blow the fuse.

[macmac]

I run the very same lamps and on a 10 amp fuse and have for the 2nd season here in NH, with out ever blowing a fuse.. I knew i was at the upper limits when I used a 10 amp fuse, and wired all the wiring from the battery thru a relay, for just being able to run these lamps when ever I wished.

I know one day the fuse will just blow due to heat and age, and when it does I can pop in a another 10. I am wired in 16 ga now and prefer a fuse as 'the weak point'.

In other applications I have suffered wiring fry with out taking the fuse, ie Chevy van and dead shorted dome light. What a mess that was, and in OEM wire.

So it is certain one of SlowMo's lamps are the fault.

[moenko]

Hi again, mac A 16 gauge wire will never get TOO warm when only conducting 9 Amps, so you're pretty certain that the 10 Amp fuse will hold up. The key is not to use a fuse rated higher than the wire's ampacity... any smaller fuse for a given wire will be safe because, as you correctly said, it will blow LONG before there would be any damage to the wires :)

Jeez, I'm WIRED

[MikeInFla]

Originally Posted by macmac

So it is certain one of SlowMo's lamps are the fault.

I'm really starting to think it's one of the lamps. Maybe I'll go get another set just incase.

[macmac]

SlowMo, I am sure one of the lamps IS the problem. I just can't tell you which one. Pull the wire from the dual bullet connector if you used it, so one lamp only wors and see if that one blows the fuse. If it does you have the bad lamp. If not un-plug it and run the other one.

One of them has to blow the fuse.

If you do blow the fuse with both of them on a independant basis then the wiring between picking up (+) volts to the lamps is suspect, but I have my doubts in such a shor time any wire could be chaffed that bad unless, say some one really pulled hard on a wire fed thru crashbars or something like that.

I think the problem is going to be with the cloth insulation at the lamp exit for the wire.

[moenko]

If it's not the lamps are not the cause, I would bet money you have some loose connection somewhere ... something to double-check on....