Vehicle electrical questons

[Mex-Busnut]

Dear Friends,

I am certainly very grateful to all of you who have kindly educated me on various and sundry bus-related matters.

I would like to ask the experts about the vehicle electrical system. We are completely rebuilding ours, as the 30-year-old installation was a terrible mess of melted cables, multi-patched wiring and long runs of cable ending in bare wires that created some awesome sparks against the center frame rails. No wonder I couldn't keep my vehicle batteries charged when parked!

1. Which vehicle systems would you use a thermal breakers on, as opposed to fuses?

2. Can somebody give an idea of good amperage size for these breakers?

3. How many amps do you consider for the Jake Brake? This line had neither fuse nor breaker.

4. In what cases is a fuse preferable to a thermal breaker?

Thanks in advance, and be blessed!

[zubzub]

The buses I have worked on only had thermal breakers (by this I presume you mean auto reset breakers).  I think they are great.  I doubt I would use fuses anywhere, though perhaps on a system where I would not be aware of the breaker cycling (water heater?) they could be a good idea.  I'm pretty sure if it wasn't for their size and expense, cars would have auto resets ('cept then owners would just drive around with cycling breakers until something caught fire).
Anyhooo the AR breakers are great they speed up trouble shooting, and get to the side of the road safely.
As to amps/wire guage etc there are charts online, many here just wire in 12 gage so they don't have to worry about the 10 amp loads, but everything is relative, the resistance of long runs requires bigger  gauge etc....  There are many here who know this stuff by heart, I don't, I always need to look it up.

[Busted Knuckle]

Steve again I am going to praise Setra coaches! On the '86-'02 "200" (215-217 here in N. America) Series models they use breakers exclusively! And I have come to love them!
However on the '03 and up "417's"they have many many blade type fuse that I am not so fond of!

And our '97 Dina uses a fair amount of the blade type fuses too.
 BK  

[pvcces]

If you think about the effect of something turning off and not turning back on again, I think that you will see that some things ought to have the AR breakers. Required vehicle lighting comes to mind, and perhaps the Jake brakes. A DVM will show you how little current that they draw.

Convenience lighting would be another matter. What about the stepwell light? That could be a liability item.

What about your heating and cooling equipment?

I understand that vehicles and boats are supposed to have a minimum 16 gauge wiring.

That's probably good up to 10 amps or so. Chassis wiring limits are different than house wiring. You should check that out.

Then, there's the field circuit for the generator or alternator.

As far as I know, our GM did not have any fuses. And our wiring is still good after 47 years.

A good plan would probably not have loads exceeding 80 % of the circuit breaker protection.

Good luck.