Why do cars still have fuseboxes?

It used to be that in houses all the electrical systems were wired through a fusebox.

But now they’re all circuit breakers, which are easy to reset and don’t require buying and installing a new fuse. They’re also safer, because with fuseboxes people sometimes wedged a coin into a burned-out fuse “temporarily” and caused a house fire.

So I guess I have two questions here:

  1. When did fuseboxes give over to circuit breakers?

and

  1. Why don’t modern cars have circuit breakers now?

My only guess as to the latter is that cars bounce around more than most houses, so circuit breakers could trip accidentally. But that just seems like a design feature that would be easy to work around.

1. When did fuseboxes give over to circuit breakers?
Sometime around WWII.

2. Why don’t modern cars have circuit breakers now?
The loads on home circuits are changed whenever anyone plugs in a new load. With a 1500 Watt hairdryer drawing almost fifteen amps, it is easy for a homeowner to plug enough stuff into a circuit to overload it. The loads on most auto circuits do not change after the car leaves the factory, and the fuses can be sized for a specific load.

To expand on that answer:

When a breaker trips in your home, it’s because you plugged too many things in to one circuit. You then unplug or turn off something, then reset the breaker - much more convienent than getting a new fuse.

When a fuse blows in a car, it’s because something in the car’s electrical system is shorting out. In that case you don’t want the power to be re-applied to the load until the car has been checked out and repaired. So having circuit breakers wouldn’t be much use, since you’re looking at repair work anyway.

>> When did fuseboxes give over to circuit breakers?
>> Sometime around WWII.

Really? I doubt it. I think circuit breakers have become widespread much more recently.

At any rate, circuit breakers are bulkier and more expensive than fuses. For reasons already said, in a car fuses very rarely blow and when they do it usually means a trip to the garage anyway.

But they have circuit breakers on aircraft (well, aircraft made after about 1980 in my limited personal experience).

I think sailor nailed it; circuit breakers are more expensive. Given the number of cars produced, car manufacturers are loathe to increase the cost of a car by even a small amount per car, because it really mounts up.

On the other hand, (as the owner of an '88 Caddy), I still don’t know why car manufacturers make the fusebox so damned hard to get at.

My house (#1) built in the 50’s had fuses so maybe CB’s were available around WW2 but they weren’t standard.
My parents house was built in 72 and had CB’s.

So CB were standard between 50 and 72

Bottom line is this: There is absolutely no advantage to using circuit breakers in a car. When compared to a fuse, a thermal or magnetic circuit breaker is:

  • Larger
  • Heavier
  • More expensive
  • Less reliable
  • Less accurate
  • Slower actuation time

Sure, a circuit breaker is more convenient, but this is not factor on an automobile (unlike your home).

While a blown automobile fuse can mean a problem in the circuit, this is not always the case. They occasionally fail from apparent “old age,” in which case replacing the fuse is all that is needed. Many cars provide a spare fuse of each size (amp rating) in the fusebox for this purpose.

If the second fuse fails, it’s testing time.

Usually when I blow a fuse in my car, I just replace it. And that’s all that was needed.

I did own a truck once that blew every fuse I put into it almost immediately, and it did in fact have a bad wiring harness. But that’s unusual.

Crafter_man has it right.

Scruff, the reason they make the automotive fuse panel so hard to get at is:

  1. They need the easily-accessable room for the stereo/EQ, climate control panel, cup holders, ash tray, and other luxury/convenience items.

B. Nobody ever looks at fuse panels when thy’re buying a new car.

III. Automakers are the leaders in the conspiracy to destroy my spine.

If power goes out to an essential system in a car, you coast off the road and replace the fuse.

If power goes out to an essential system in an airplane in flight you die a flaming death.

It seems most of the replies have assumed that cars don’t have circuit breakers. But some in fact do.

A car I bought new in 1987 had a circuit breaker for the A/C unit. It tripped a couple of times during the few years that I had the car.

The car I have at the moment, made in 2000, has a similar device except that it resets itself after a few minutes. I don’t have to do it manually.

So yes, you do find circuit breakers in cars.

car voltages arent constant so the amps must not be either
old type fuses are insensitive and take a while to blow …millisecond wise
cb’s are very sensitive and could blow everytime a bulb went leaving you completely in the dark
this is what happens in my house if a bulb blows
easy to pop down stairs and flick the switch back up
but a bit disconcerting on a fast bend in the dark if a tail light goes
imo only :slight_smile:

Our house was built in '55 and has circuit breakers.

I will say that circuit breakers and breaker boxes did get quite a bit nicer since this one was made.

In most small aircraft, a total electrical system failure would not bring the plane down.

They generally run on dual magnetos, and these require no outside power to operate. If the engine is spinning, there is ignition.

As Desmostylus pointed out, circuit breakers are used in cars, but only in a few applications. Every car has an array of fuses, some cars have a few CB’s (typically 1-3). Power window and A/C circuits seem to be the most common place for them.

Every automotive CB I’ve seen is self-resetting. They are available in different amperages and can be installed in place of fuses, though I don’t recommend that as a matter of course. One situation where it could be helpful, though, is with an intermittent short circuit that occasionally pops the fuse but then functions OK for a number of weeks or months. Until it’s feasible to find and fix the short, a CB is a lot more convenient than fuses. Don’t use one if the short recurs in a brief time period, there’s a risk of causing damage.