# Are circuit breakers acceptable in place of fuses?



## psychotic (Jul 14, 2008)

With a multi-amp system, I tend to run 0 gauge from the battery, with a circuit breaker about 6 inches away, using the total amperage from all amplifiers as a guess for what amp the breaker should be. Then I run the 0 gauge back to the amps, and split it into 4 ga with a fused distro block... Now, I'm not against fuses, its just no one around my area sells them at the amperage or type I need. If I do find a place, they are extremely overpriced. I usually turn to the internet, but then if a short does somehow happen and a fuse blows, I have to go back on the internet.

I was wondering if it is acceptable to run this the same way, only use a non-fused distro block with circuit breakers immediately after with the same amp rating as the fuse that would be used. This way if there is an accidental short, I can figure it out, fix the issue so it doesn't happen again, and just flip the circuit breaker back on.

I know the main issue here is the time it takes for a circuit breaker to trip compared to a fuse to blow, and if that time difference means a significant increase in risk. I am not sure if circuit breakers trip fast enough for car audio amplifiers, or perhaps there may be some type of circuit breaker that is meant to trip immediately like quick fuses. Can someone w/ more knowledge give me some input? 

Thanks!


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## tristan20 (Nov 28, 2005)

NO plain and simple


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## Oliver (Jun 25, 2007)

Here is a waterproof 60 amp direct current circuit breaker...


Amazon.com: MinnKota MKR-19 Circuit Breaker (60 Amp Waterproof): Sports & Outdoors

Shipment Rate
$0.00 - $98.99 $6.95 + $34.67 = $41.62 ought to do it 

quote>
The circuit breaker is designed to be the weak link in your electrical system. But that's a good thing as it's designed to fail safely. When a circuit draws more current than it is designed to handle, the wiring gets hot and problems can occur including fires.
quote>
quote>
Circuit breakers are designed to trip (fuses in your fuse box are designed to blow) and turn off power when any of the following dangerous situations occur:

* Overloaded Circuit
* Short Circuit
* Ground Fault
quote>


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## shadowfactory (Oct 20, 2008)

tristan20 said:


> NO plain and simple


Why not? I have a circuit breaker on my alt + to battery + wire in my big 3, is my car going to catch fire?


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## Oliver (Jun 25, 2007)

shadowfactory said:


> Why not? I have a circuit breaker on my alt + to battery + wire in my big 3, is my car going to catch fire?


If the wire is to small to handle the current flowing thru it and the circuit breaker does not trip {for whatever reason } a fire could happen 

Make sure your auto insurance has fire protection !

With SoundSystems you can attach a rider to your insurance to protect you against theft


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## shadowfactory (Oct 20, 2008)

a$$hole said:


> If the wire is to small to handle the current flowing thru it and the circuit breaker does not trip {for whatever reason } a fire could happen
> 
> Make sure your auto insurance has fire protection !
> 
> With SoundSystems you can attach a rider to your insurance to protect you against theft


Well I did go the overkill route with 0 gauge for that wire but it sounds like I need to pick up another fuse holder to replace that breaker. 

And the only theft I've had so far is cologne...


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## Oliver (Jun 25, 2007)

from BCAE
quote>
Type of circuit breaker:

Some circuit breakers use a magnetic actuator to trip the circuit. In this type of breaker, the current flow through the electrical device (amp, fog lights...) passes through an electromagnetic actuator. When the current flow reaches a preset level (determined by the current rating of the breaker), the magnetic field in the electromagnet is strong enough to trip the breaker and allow the contacts to open. This type of breaker generally has to be manually reset. A well designed 'magnetically' actuated circuit breaker can operate very quickly (possibly as fast as or faster than a fuse of equal current rating). 
quote>

From BCAE...
quote>
Wire Gauge..........Current Flow 
0 awg.................330 amps

.............................Max Total Amp Power
Class AB (60% eff).........2731 watts
Class D (75% eff)........3414 watts

quote>


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## Oliver (Jun 25, 2007)

psychotic this place is in FL.

Eaton Corp

Address: 2250 Whitfield Ave
Sarasota, FL,
34243-3926
Phone: 941-758-7726

products:

circuit breakers, Air circuit breakers, Molded case circuit breakers


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## jrfonte (Apr 7, 2009)

i have stinger 150amp circuit breakers on my 1/0 power arent they pretty much designed for this application.
here is a pic of one
Stinger SGP90150


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## MidnightG35X (Feb 5, 2009)

jrfonte said:


> i have stinger 150amp circuit breakers on my 1/0 power arent they pretty much designed for this application.
> here is a pic of one
> Stinger SGP90150


I am wondering the same thing... I have that exact same breaker. I have a kicker fuse holder I could use, but a circuit breaker seems like a better idea if it performs the same as the fuse.


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## tristan20 (Nov 28, 2005)

a circuit breaker takes longer to trip than a fuse.

Thats why most are not recommended


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## jrfonte (Apr 7, 2009)

mine trips instantly if you ground out the power cable. but its only there to protect the main power wire the amps all have there own fuses built into them so its not there for the amps just the power cable. if your amps dont have fuses built into them then you need fuses in the distro block right before the amps to protect them. but i would rather have the breaker on the main power simply because i dont like buying and having to replace those expensive fuses i would rather just flip a switch and reset it. but i have one in my car and one in each truck and have never had a problem out of any of them.


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## socal28 (Nov 14, 2008)

I'm using a circuit breaker by the battery and fused (mini ANL) distribution by the amps.
From this thread, this is not a good idea?
Or we are just talking about using a circuit breaker by the amps?


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## jrfonte (Apr 7, 2009)

the op was talking about using a breaker by the battery and fused distro blocks at the amps. which some one said there was a problem doing that but there are some that are designed for this application. so what is the problem with using it as long as you have another fused distro block at the amps or if your amps have built in fuses in them? some breakers are made to trip instantly and yet there are a lot of those big fuses that are made to be slow blow.


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## HIS4 (Oct 6, 2005)

tristan20 said:


> a circuit breaker takes longer to trip than a fuse.
> 
> Thats why most are not recommended


Aren't the most common fuses time delay so they take a little longer to blow. Breakers are instant. Regardless, either one is fine because wire can withstand a transient overcurrent condition without burning up the insulation. I used breakers both at my battery and in front of each amp (which didn't have internal fuses) in my last install. It made it easier for me to disconnect power to only certain amps during testing.


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## tristan20 (Nov 28, 2005)

Circuit breakers usually take much more current to trip than a fuse.
Also a longer tolerance level


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## bboyvek (Dec 16, 2008)

circuit breaker>Fuse

Plain and Simple


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## tristan20 (Nov 28, 2005)

fuses or circuit breakers?

Circuit breakers behave similarly to fusetrons - that is, they tend to take longer to trip at moderate overloads than ordinary fuses. With high overloads, they trip quickly.


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## Mark Eldridge (Jul 23, 2008)

A good quality circuit breaker will be fine. IF you understand the ratings for fuses and circuit breakers, and use the appropriate one, it will not matter which one you use... They can both work equally well. 

Circuit breakers are not inherently designed to take longer to trip than a fuse. 

All fuses like the ones we use (ANL, AGU, ATC, etc), as well as circuit breakers, are required to meet UL listing rating standards at 100%, 110%, 135%, and 200% of rated current. 

But, the specific ratings at each over current level are determined by the voltage and current rating of the device, as well as what it is designed to protect. 

In general, (and these are not specific numbers, because the ratings vary depending on the specific device design parameters) fuses and CBs are required to carry 100% rated current indefinitely and not have a rise of more than 75 degrees C, must carry 135% rated current for an hour, and must open within a couple of minutes at 200% of rated load (specific time depends on actual current rating). 

Fuses and CBs can carry far more than their rated load for very short durations. In the charging system class I teach, we charge and discharge a 1 Farad capacitor through a 40 amp fuse with a direct short many times, and the fuse doesn't open. The capacitor is discharging several hundred amps of current through the fuse, but it does so in such a short time that the fuse doesn't get hot enough to open. 

As long as you choose a circuit breaker that is rated like the fuses you are replacing, you will not have any problems. And, yes, the magnetic circuit breakers are far better devices than the much cheaper thermal CBs, and the hydraulic magnetic CBs are even better. But, a magnetic circuit breakers will be significantly more expensive than comparably rated fuses. 

I use strictly magnetic hydraulic CBs on all the high powered equipment in my own system. They are far easier to use, because they can be manually connected or disconnected when servicing the system, and if they do trip, once the problem is fixed, they can simply be reset. 

Buy good CBs, and you'll be just fine. Get the wrong CB or fuse, and you might end up having a really bad day...


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## Monte B. (Aug 12, 2008)

Mark-
Where do you get your hydraulic magnetic CB's?


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## psychotic (Jul 14, 2008)

Thanks for the information...

I want to clear some things up for some confused people...

It IS ok to use a circuit breaker near the battery, and then run it back to a fused distro block.... because the fuses are still protecting the amps, and the circuit breaker would obviously trip if the 0ga wire accidentally grounded. 

The circuit breaker I used before has to be manually reset, it will stop the circuit immediately in case of a short circuit, this post was mainly asking if it was also ok to use AFTER a distro block IN THE PLACE of fuses.

the magnetic CB sounds like the best solution, as mark elridge said, fuses blow due to heat... 

Earlier it was said that...
"If the wire is to small to handle the current flowing thru it and the circuit breaker does not trip {for whatever reason } a fire could happen 

Make sure your auto insurance has fire protection !

With SoundSystems you can attach a rider to your insurance to protect you against theft"

the amperage of the CB should be the same as a fuse you would use.... if the wire is somehow too small to handle the current, but the CB or fuse CAN handle that current, then your wire itself becomes the fuse (fire).... this is very unrealistic.... 

For those who use CB's by the battery only, that is fine if you have fuses closer to the amplifier(s), because the CB is just there to protect from a short circuit (HIGH overload, instant trip), not really to protect the amps (may just be moderate overload)... instead you have fuses protecting the amps... 


"I use strictly magnetic hydraulic CBs on all the high powered equipment in my own system. They are far easier to use, because they can be manually connected or disconnected when servicing the system, and if they do trip, once the problem is fixed, they can simply be reset."

This is exactly why I wanted to use CBs.... it is not because I always blow fuses, its for accidental shorts mainly, that I can just fix the problem and reset the CB...

Mark, I have a magnetic CB, but haven't heard of hydrualic CBs..... can you at least post a link to one, or mention where you can find these??

one other question, even though my CB is magnetic... are the thermal CB's going to be approximately equal to time it takes to trip for an equal amperage fuse (which also relies on thermal overload)?

And a$$hole, thank you for that business info... thats only 20 min from me!

Thanks everyone for the info


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## Oliver (Jun 25, 2007)

Hydraulic-magnetic circuit breakers | Machine Design

Carling Tech: Hydraulic, Magnetic & Thermal Circuit Breakers

http://www.eaton.com/ecm/groups/public/@pub/@eaton/@ee/documents/content/pg01100001e.pdf

P&B W69-X2Q12-15 Magnetic Hydraulic Circuit Breaker - eBay (item 360143488610 end time May-15-09 09:28:21 PDT)

You'll find something above...mebbe ^^^^


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## m115919h (Jun 12, 2008)

As long as the amperage rating of the circuit breaker is suitable for use on the wire that will be running to it, I don't see any problems with use a circuit breaker. Basically if a wire is suitable for 60 amps then a 60 amp circuit breaker would work just fine. Sorry I don't have a NEC book in front of me right now, so I can't give the exact wire size that is suitable for 60 amps. 

In short if you are replacing a fuse with a circuit breaker with the same amp rating, I don't see a problem with that.


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## psychotic (Jul 14, 2008)

jrfonte said:


> i have stinger 150amp circuit breakers on my 1/0 power arent they pretty much designed for this application.
> here is a pic of one
> Stinger SGP90150



Both of the circuit breakers you have posted are not like the one I bought from.... audiopipe?? I dunno if they still exist... but anyways, both of those posted are the typical design of circuit breakers. The one I have is designed the same way a waterproof fuse holder is... There is a 0 gauge terminal on each side, which you tighten with hex screws, then the ends have the plastic screw-on cover with an O-ring to seal it.... so if you can imagine a regular straight fuse holder, and replace the middle tube with a square circuit breaker... that is the design of mine. It is definately made for car audio (no connectors needed, the hex screw in design, the waterproof cap to screw on after, etc). Mine is 200 amp though, as my last system had an amperage total of 240.


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## tinnitus (Apr 28, 2009)

psychotic said:


> With a multi-amp system, I tend to run 0 gauge from the battery, with a circuit breaker about 6 inches away, using the total amperage from all amplifiers as a guess for what amp the breaker should be. Then I run the 0 gauge back to the amps, and split it into 4 ga with a fused distro block... Now, I'm not against fuses, its just no one around my area sells them at the amperage or type I need. If I do find a place, they are extremely overpriced. I usually turn to the internet, but then if a short does somehow happen and a fuse blows, I have to go back on the internet.
> 
> I was wondering if it is acceptable to run this the same way, only use a non-fused distro block with circuit breakers immediately after with the same amp rating as the fuse that would be used. This way if there is an accidental short, I can figure it out, fix the issue so it doesn't happen again, and just flip the circuit breaker back on.
> 
> ...


not unless it is specifically designed for 12 volt car audio use,,,,

car amplifiers that say they are rated for lets say 500 watts rms,, at certain frequencies can produce a trasient output almost double their rating for a very short period of time,,, sometimes shorter than the human ear can hear,,, and breakers that are too sensitive can trip even when they shouldnt,,

breakers that are not sensitive enough will trip too slowly and you can have problems....

fuses go by heat,, and thermallity is pretty constant with fuses,,, so when they pop.. they were supposed to...


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## HIS4 (Oct 6, 2005)

psychotic said:


> With a multi-amp system, I tend to run 0 gauge from the battery, with a circuit breaker about 6 inches away, using the total amperage from all amplifiers as a guess for what amp the breaker should be. Then I run the 0 gauge back to the amps, and split it into 4 ga with a fused distro block... Now, I'm not against fuses, its just no one around my area sells them at the amperage or type I need. If I do find a place, they are extremely overpriced. I usually turn to the internet, but then if a short does somehow happen and a fuse blows, I have to go back on the internet.
> 
> I was wondering if it is acceptable to run this the same way, only use a non-fused distro block with circuit breakers immediately after with the same amp rating as the fuse that would be used. This way if there is an accidental short, I can figure it out, fix the issue so it doesn't happen again, and just flip the circuit breaker back on.
> 
> ...


I had my previous system setup exactly this way. 150A breaker at the battery with 1/0 AWG going from the battery to a 5F Alumapro cap. Then from the cap I had 4 AWG going through a 100A breaker for each amp. The amps had no internal fuses so the breaker served as both protection for the amp as well as the 4 AWG conductor. I never had any problems. The breaker was rated below the maximum recommended overcurrent protection for the amps which was 125A so it would have tripped before the maximum current draw for the amp was reached. I never tripped the breaker for as long as I had that setup. The amp gains were set at minimum so it was highly unlikely that I would ever reach the max current draw.

In the case where the amps have their own internal fuses, you're not even worried about the breaker protecting the amp because the internal fuses serve that purpose. All you're worried about is protecting the conductor from an overload condition. Conductors can withstand a transient overload condition without burning up. It when there's a long term overload that the insulation starts burning up and the risk of fire increases. The breaker will trip long before that happens provided that the breaker rating is within the max current ampacity of the conductor.


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## less (Nov 30, 2006)

First of all, thanks for this question. I was actually getting ready to post a related question and found this thread.. searching... it works! I think the answer to my question resides in the fact that no one mentioned it in any post so far. I'd heard that people were having issues with breakers made for car audio - in that they were only working for a year or so, and then malfunctioning. I don't want to spend the $ for a good one - made for the elements - and then have to do another one later when it breaks.

Perhaps this is the "old man" in me, but it is REALLY DISCOURAGING to see people post opinions here without adequate information. Personally, I try to limit my posts to things I actually know, and while there are a lot of things I think I know... I don't answer peoples questions unless I am genuinely informed - or I at least state the fact that I might be wrong, if there is a shred of doubt.

In this case, there is some room for debate, sure, but flat out saying circuit breakers are out and don't work fast enough - only to see others posting that there are many types designed to work quickly - just shows that someone doesn't have their facts straight. Iinstead of being helpful, they're actually confusing the issue! While I understand that it is much less likely for a fuse rated a certain value to actually cause a trouble by not opening the circuit at that level - than it is for there to be a similar issue with a circuit breaker, simply because of its more involved mechanical build, creating panic about good circuit breakers being unsafe is probably an overstatement, right? 

Yes, one can fail to go off - but a fuse can be mismarked at the factory, trust me! Hell, I had a surgery and had green ink written over the spot they were to cut... and they cut and went down the wrong side!!! So don't think a run of 80amp fuses never left the manufacturer with a 40amp plastic case around them <WINK>!

Thanks to those with well informed input for chiming in. I'm finally going to change from a run of 4ga and a run of 8ga to a single run of 1/0 - and I am building a spiffy little cubby to hold my rear battery, relay box and fuse block... and I am looking very closely at breakers (appropriate ones). Has any CB user ever had trouble with "early failure" on a breaker? I was told it was common, but the source was suspect.

Thanks
Less / Jim


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## keep_hope_alive (Jan 4, 2009)

fuses > breakers as far as the time-current trip curve is concerned. 

breakers are easier and better for 3 phase motors - not applicable here.


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