starter switch

Im not exactly familiar on the 88 wiring without looking at a schematic, but normally the #10 at the dash is the feed to all the fuses which one of them should be for ignition. Certainly having the #10 wire hook to the ign key input is incorrect, and like you mentioned, its unprotected (If you call 50A unprotected). If it were hooked up like that and something either shorted or failed, you will need the fire extinguisher!!

Do you have the engine wiring diagram as well?

             Jeff...

   Sounds good!! A rule of thumb for wiring to be safe is always fuse the lines at the wire size capacity, as well as the device load. You should use a little larger than #18awg to feed the ign switch. #14awg would be my choice. Good luck!!!

Jeff and 79 are right on here. The wire has to be big enough to carry the current with as little as possible voltage drop, and the fuse has to be sized smaller than the ampacity of the wire (but larger than the current level drawn by the device). In other words, if your wire is rated at 30 amps your fuse MUST be smaller than 30 amps. The purpose of a fuse, no matter what anyone else may say, is to protect wire. With wire, bigger is always better as long as it is not so big the wire lugs cannot fit on the device terminal. Use as large of a wire as you can fit onto your device terminal.

Believe it or not, the primary purpose of a circuit breaker is not to protect wire. One of the primary purposes of a circuit breaker is to automatically break the circuit when an overcurrent is detected. This may sound, at first, as the same thing, but it is not. Circuit breakers are relativly slow acting when compared to fuses. A fuse will limit current - circuit breakers will not limit current. Until the circuit breaker heats and trips it will pass all the current made available by your voltage source (the battery in the case of a boat). For protecting wire (and preventing a fire) fuses are king. The best protection is to have both a circuit breaker and a fuse. Sadly, this is rarely done.

Don't you just hate it when someone starts lecturing?

BTW, the National Electrical Code (which DOES NOT apply to boats) rates #10 copper wire, like the wire used in buildings and residences, at 50 to 55 amps depending on the wire insulation and the installation. I would assume, wire for marine installations carries a higher amp rating but I don't know this. I would not however, use wire smaller than #10 on a 50 amp breaker unless the wire had some super-duper high temp insulation raising it's rating to 60 amps or more. #8 would be better, if you can properly fit it to the device terminal.

If you have wires smaller than #10 connected to your 50 amp breaker it would be smart to fuse those wires.

   J-I-H, as far the NEC goes, a #10 CU wire must be protected at a maximum of 30 amps, #12 CU wire at 20 amps, #14 CU wire at 15 amps etc. Of course aluminum wire is different. Also, you are only allowed 80% of the maximum current continuously (thats why you will never see a device draw 15 amps with a 15 amp cord cap). Also, just to clarify things about fuses and breakers, they in fact do the exact same job. The purpose is to open the circuit if it exceeds the cuurent of the protector. Where the confusion seems, its the time and percent overload allowed before opening a circuit. They make low voltage breakers that are fast acting as well like a fuse. They also make time delay fuses.
The silver can breakers for marine and auto use are very crude and should be illegal. Auto reset is also a problem because if there is a problem, the last thing I want is for the breaker to kick back in and fry things even more until it burns up.

PS: no hard feelings JIH. Sorry..

Wow you guys must be smarter than ole jbear. All I'm gettin is a headache. Almost as bad as that stereo and amp post a couple a days ago. Better have a cold one. I'll feel better in the AM.

john

Jeff; I think I got whatever you might need to enjoy them cold ones. I sure do enjoy to evesdrop on you guys discussing tech thing, even if I don't understand.

john

Jeff,

About you headlight brightness. You may have had another problem like a faulty connection which you repaired when you replaced the wiring.

Although the difference in wattage at the bulb is admittedly impressive the gain in wattage by going from #16 to #12 wire is actually only about 7.1136 watts. Based on your claim that the lamps pull 12 amps (which sounds about right) your lamps on high beam consume 144 watts. 7.1136 watts represents a 4.9% improvement. Personally I think that is impressive and more than I would have guessed. I based my calculations on an assumed total wire length of 20 feet and #12 wire ohming out to 1.62 ohms per thousand feet and #16 ohming out to 4.09 ohms per thousand feet. The voltage drop of the #12 is .3888 volts and #16 is .9816 volts for a difference of .5928 volts. .5928 volts x 12 amps = 7.1136 watts (total wattage gain).

But then again, maybe there is a non-linear relationship between wattage consumption and brightness but I doubt it. If there is a non-linear relationship it is probably regressive.

Sorry

   tonydjd, I will get to you soon, sorry, I want to clear things up w/JIH first. Ok jbear, I just poured myself a tall glass of Kahlua especial for a cold one.
   JIH, I dont mind telling you that you are certainly knowledgeable with this as well. Yourself, Jbear and I need to get together someday!!
   Anyway, article 310 your referring to is correct. The current a wire can carry is based upon heat factor of the insulation, its location, and number of current carrying conductors. Of course, being AC, the number of conductors allowed in a raceway is limited due to the magnetic field-not the case with DC. Also conductor length due to voltage drop is a factor, take a look at article 210.19 and FPN#4.
   As far as fuses and breakers go, I see what you are thinking. A breaker (generic) has a time period of connection before it "opens". Well, technically, fuses are in sense like a filament of a lightbulb. When cold, the resistance is near zero, but as it heats up, it passes liss current because the resistance goes up. Now, during a direct short, there is still a time period of non-current limiting until it heats up. Like my headlight deal, filaments (like a fuse) are a non-linear device. Take a ohm meter and read the resistance of a 100W 110v household bulb, take the reading, and figure the current using Ohms law. The bulb should read around a little less than 100 ohms, but it doesnt.
   They also have breakers that are magnetic where they are the MOST percise and used in sensitive electronic equipment. It opens the circuit with no time delay or overcurrent(practically speaking). Also, read ARTICLE 240.20(A) where fuses and breakers serve the same purpose.
   Anyway JIH, you think we should UPS Jbear some harder cold ones after he reads all of our debates and runs for another????
   You are a hell of a guy and fun to debate with!!!
                            

Jeff, I think we are arguing of the meaning of the word "is".

We sure derailed Tonydjd's thread didn't we. That will teach him to ask an electrical question. Sorry Tony. I will back out of here.

But first Jeff, are you saying the heating of conductors in an AC circuit is the result of induction and that conductors in DC circuits will not heat up as much? Is that what you are saying?

79: These guys lost me awhile ago, I'll admit. I don't understand a thing they are talkin' about but I sure do enjoy reading them.

Besides, I always like your answers 79. I can usually understand them.

john

    Yes, BKHP, I agree!!
    JIH, we are not arguing are we?? I hope not. You are very intelligent, and where the heck did you learn all you know?? Around here, its difficult to find someone who doesnt give me a blank look when I mention Ohms Law. Any way, I certainly dont want to destroy anyones post, so I will get back to the topic. As far as your question goes about induction in AC circuits, go to article 300.20 and I will keep this post short. Would be neat to meet in person someday, could talk for days I bet!!
                          Jeff..

BKH; Forgot most of it the day I walked out the door. Don't mind at all either, now if I could only remember where my keys are.

I bet tonydjd will think twice before he starts another thread.

It is fun how these things take off.

john