breaker amp rating?

I am rewiring a 1977 VW Golf from the ground up.  My cousin is the head aviation mechanic for a health insurance company.  Long story short, he handed me a box full of 2-3k worth of aviation circuit breakers that were speced out and pulled out of a jetliner.  Anyone not familiar with aviation mechanics, they throw out tons of good parts everyday simply because of the amount of hours on them increases their failure potential. 

The big question...  Aviation electronics run off of 28vdc.  Automotive is 14vdc (for all intents).  I am a wizard at wiring stuff up, but once Ohms Law is involved, forget it.  But studying for a little while I come to the conclusion that a 28vdc crcuit breaker rated at 5 amps, will not trip until 10 amps when used in a 14vdc application.

Is this conclusion correct? 

Current is current.  It is not affected by the voltage.  The following breaker does not say it is rated at different current for different voltages.  It is a 20 amp breaker from 5 to 50 volts. 

thats not true IAAI. think of it like this........we know by using Ohms law that if you run  2 35watt lights in a 24v system, the lights will draw nearly 1.5amps of current each. a total amp draw of 3amps. connect that to a 10 amp toggle and a 5amp circuit breaker and no problem. now.......connect the same 35 watt lights to a 12v system and the total current draw is near 6amps. no problem for the switch, but now the circuit breaker trips all the time.

that is what he was asking about earlier.

which i should have been more clear in my answer before, sorry.

t3bunny, if you use the Ohms law chart at the top of the page, youll be able to calculate all the stuff you need.

I have played with the Ohms law calculator but might have been going about it wrong.  Even amongst ones smarer in such thn I am, there also seems to be cofusion.  I seriously have issues getting my head around power, current, amps, watts and all this so staring at the calculator realy isn't giving me any numbes that I can fathom.

First lets discuss the breakers.  I do not see in any datasheets anywhee that they are 5-50vdc (btw firgive me if my tone sounds... bad.  Its confusion and lack of understanding).  They are rated for 28vdc.  Now looking at these does bring up the fact that nowhere did they mention differant amp ratings for dfferant voltages...  Most of the ones  happen to have are 5amp breakers with a small number of 7 1/2amp, 15amp, and maybe a couple 20amp.  Lets ignore all the values except the 5amp as I have the most of these.

The variable on my car is the voltage is lower that what these breakers were itended for at 14vdc.  I was talking to a customer the other day about his drag racing setup he wants me to install a new harness on.  His system is setup to run 16vdc and according to his research he has to rn bigger fuses/breakers to power the same systems.  Not sure thats relivant or even true but lets look back to this. 

Lets use a 100watt lightbulb as our test supject.  Now my uderstandign of why somebody would up the voltage on a race car is it takes less energy to drive everythign and its more efficiant.  So would a 100 watt bulb always consume 100 watts in any voltage system???  Anyways lets plug in numbers assuming this is so. 

14 vdc with a 100 watt bulb generates 7.1 amps 

16 vdc with a 100 watt bulb geneates a lower 6.25 amps

28vdc with a 100 watt bulb generates an even lower 3.57 amps. 

In my first post I was thinking that a breaker rated at 28vdc for 5 amps could replace a 10 amp fuse in my automotive application running 14 volts.  I think I was playing with making the current match up.. not sure. 

So I am seeing this...

Oops hit a bad button..  Anyways...

If electricity were a fluid like water then:
 
Volts = PSI
Amps = GPM potential
Watts = GPM delivered
Wire size = Pipe size
Ohms = Friction losses due to length + diameter of pipe
 
With more PSI you can pump more fluid through smaller pipe.
That is why lower voltages require larger wire (larger pipe) size.

Now things start to make some sense.  Avionics uses miles and miles of wire.  Running higher voltages could substantualy lower the weight of a plane by allowing smaller diameter wire to be used. 

It also seems that increading voltage loweres the amp load.  So this would DEFINATLY seem to point out to me that running a 5amp/28 vdc breaker on a circuit that originaly was running a 10 amp/12 vdc fuse is way out of line.  Nor does it seem that a breaker listed at 5 amps on a 28vdc system could ever be used for a 10 amp breaker on a 14vdc setup. 

Rewiring this car is going to be extensive.  Is ther any way to make use of these 5amp breakers?  The vast majorit yof these circuits are 10 amp fuses.  Can I run two breakers in parrelell? 

If not, looks like I either scratch the idea all together or I would have to split most of these circuits.  Or increase my voltage but thats not very practical...  ugh forgve my spelling errors.  I want spellcheck and sleep lol.  This problem is g=keeping my brain working at full speed.

Breakers (and fuses) have no reference to ground, and therefore have no way to determine "voltage". 

The voltage rating is the max amount of voltage the overload device can safely (and reliably) break at x amps (consult data sheet).  To test this theory run the breaker at 5A at 14.4vdc for 5 mintues and then run the breaker at 10A at 14.4vdc until it trips.  It should take anywhere from 10-60 seconds to trip at 10A (maybe more or less, again check datasheet). 

You can wire the breakers in parallel to achive 10A, but why would you want to do that?  Free is great and all, but if you are going to rewire the entire car I would recomend that you focus more on "right" then "free"

Thanks guys!  I really appreciate all the help and I think I have a MUCH better idea of whats going on now too. 

As for right vrs free, I have a few options available to me.  I can actually replace the whole car harness with one from a newer car I have that I know is good.  Needs some work to fit it and make it work, but not a big deal.  Still the weak point in any setup is using an old fusebox.  If I rewire the car from the ground up running all new stuff, then I can split up the circuits and get around most of these concerns.  Theres only 1-2 circuits I can think of that might need to run parallel breakers. 

So whatever I decide to do I now have a better understanding of whats going on and can make an intelligant choice in the matter. 

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The tounge does not make a good test light...