Jump to content
HybridZ

Why not circuit breakers instead of fuses?!


Recommended Posts

I am getting ready to re-wire the Z this summer.. and I really like aircraft style circuit breakers. All the airplanes i've flown obviously have circuit breakers and my intensive MD DC-10 course covered the entire electrical system in great detail.

 

I realize that the only 2 drawbacks to circuit breakers are

1) cost

2) you can reset a circuit breaker over and over again which would allow the wire's to heat up and potentially cause a fire.

 

On a track/street car however; if the breaker trips its like a fuse blowing.. FIND the source of the problem first rather than attempting to keep resetting it. Only an idiot would continue to reset the breaker and cause a fire on a road car

 

Aircrafts use circuit breakers because if the airplane is going down.. the pilots and passengers would much rather burn up the wiring but enabling an extra few seconds to run a accessory/device to save their lives than dig around for a stupid fuse and keep blowing them. Circuit breakers on airplanes save lives.

 

On a track/street car? over time I would never have to buy fuses again and carry spares, if the breaker trips its easy to see and it looks really effn cool.

 

Anyone gone with this approach before or seen it?

Link to comment
Share on other sites

I2) you can reset a circuit breaker over and over again which would allow the wire's to heat up and potentially cause a fire.

 

It is precisly this reason that I never use auto reset breakers.

 

In all my years of electrical experiance (it's lots, it's what I do for a living), I have never seen a fuse blow with out a very good reason. These reasons are usually overloading a circuit, such as plugging in a 400W power inverter to a cigarete socket and running that inverter to a heat gun set on high, or a problem with an item attached to that circuit, or the wiring in that circuit has been damaged.

 

That is why even in the long run, fuses will still usually be cheaper, since they really are rare to blow on a properly wired car, are lighter, because, hey, every ounce counts to some people, and they are a finite protection, the fuse blows that circuit is dead, no chance of the wire becoming warm and starting a fire.

Link to comment
Share on other sites

  • Administrators

That is why even in the long run, fuses will still usually be cheaper, since they really are rare to blow on a properly wired car...

 

My contention isn't with fuses as much as it is the commonly available fuse blocks. I've had some leave-you-stranded issues with aftermarket fuse blocks (again, not the fuse or downstream circuit), so I've begun avoiding them.

 

As Bo alluded, I've grown fond of CB's. They can be pretty easy to install and my confidence is greater.

 

An example installation...

 

http://forums.hybridz.org/showpost.php?p=753989&postcount=1

Link to comment
Share on other sites

I have had bad experiences with aftermarket fuse blocks when pushing more than 20 amps through a circuit. My electric fan kept melting the bus it was on.

 

Six Shooter, no one is mentioning using auto-reseting circuit breakers for the very reasons you posted. :) If the circuit trips, it is tripping for a reason. However, I can see the appeal of using a manually resetting circuit breaker. I just keep a butt load of fuses in my car.

Link to comment
Share on other sites

Let's say you're on the last lap of the Indy 500 and a fuse blows. You're done and finish 25th. If you have a circuit breaker you can reset it, cross the finish line, collect the $1M prize money, and then worry about the problem.

 

A circuit breaker in a race car is a great idea. Its also a good idea on a street car if the owner is intelligent and thoughtful. New cars with 24, 36, and 42V subsystems already have curcuit breakers installed.

Link to comment
Share on other sites

Don't some (cheaper) production cars have them as well? I can't remember if it was a Quest Minivan or Subaru Legacy Wagon that had them but I know I've encountered them before.

 

When it tripped, you would click it back to the "ON" side, just like a circuit breaker in your home.

 

Hmm... I'm getting set to rewire mine as well, I'm definitely going to look into this more.

Mario

Link to comment
Share on other sites

A lot of American cars have auto-resetting circuit breakers on the headlight circuits which cycle quickly. The thought is that it reduces full current time so the wiring stays cool (a "duty-cycle" of sorts") even with a partial short and yet you have enough light to drive on the darkened country roads.

Link to comment
Share on other sites

Let's say you're on the last lap of the Indy 500 and a fuse blows. You're done and finish 25th. If you have a circuit breaker you can reset it, cross the finish line, collect the $1M prize money, and then worry about the problem.

 

A circuit breaker in a race car is a great idea. Its also a good idea on a street car if the owner is intelligent and thoughtful. New cars with 24, 36, and 42V subsystems already have curcuit breakers installed.

 

For starters, I don't think any of us on Hybrid Z are running Indy. :lol:

 

Second of all, if that hypothetical car you speak of, opens the mystery protection device (fuse or circuit breaker), on the last lap, and then is able to be reset/replaced immediatly to complete the lap, that shows me that the circuit was improperly designed and/or protected. This shows me that the circuit in question has been runing near or at the limits of that circuit, causing the circuit and protection device to be heated at a pretty constant rate for most or all of the race, and the protection device finaly opened, protecting the circuit, just as it should. Since this protection device can be reset rather quickly (it would have to be to stay with your example, even then a few spots are guaranteed to be lost), this shows that the circuit is able to cool down quickly, and allow a shorter time than was initially seen before the protection device opens again. You start getting into heat cycling the circuit, which will also cause the wiring itself to build resistance after a few heat cycles reducing the ability for the wire to effectivly transfer power, which will cause the "problem" to show more frequently at shorter intervals, even when starting from a cold start situation.

In this example, the loads should be split up over more protection devices, to allow the protection device to perform it's intended job, protect the circuit in the event of a short circuit, or a failed device (usually also causing a short circuit). A properly designed electrical system will NEVER open a protection device under normal operation.

 

Six Shooter, no one is mentioning using auto-reseting circuit breakers for the very reasons you posted.

 

True, but it was alluded to, in the original post, with the airplane example.

 

My contention isn't with fuses as much as it is the commonly available fuse blocks[/i']. I've had some leave-you-stranded issues with aftermarket fuse blocks (again, not the fuse or downstream circuit), so I've begun avoiding them.

 

The very same thing can happen with circuit breakers, some are not made as well as others, and you do need to spend some good money a good fuse block, for it to last and be reliable. I only ever use fuses in my additional circuits and other than AGU fuses (large glass) of the last few years from a certain supplier, I just don't ever have a problem with the fuses, or fuse blocks.

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

×
×
  • Create New...