# Breakers vs Fuses?



## Muddrummer14 (Oct 31, 2011)

My question is concerning overcurrent protection on a hypothetical piece of electrical equipment.

Generally speaking why and what are some instances where we as electricians protect any given piece of electrical equipment with a fuse instead of a breaker? 

Aren't Breakers more convenient in that we only need to reset the tripped breaker, where as fuses need to be completely replaced?

Feel free to call me green or bust balls on this one, just wondering and had to ask!


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## oliquir (Jan 13, 2011)

fuses are generally cheaper and faster than a breaker on short-circuit fault. some specialized fuses are able to interrupt current short circuit a lot better than a breaker.
if i check residential breaker they are generally listed at 10kA interrupting and some small CC fuse are rated at 200kA


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## wildleg (Apr 12, 2009)

breakers are known to fail (miserably)

fuses can fail, but rarely fail to open. fuses in combination with properly sized overloads IMHO are much safer than breakers, although I think breakers are more reliable nowadays than ever, and for ordinary purposes (read residential) they are fine. JMHO


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## Wirenuting (Sep 12, 2010)

Muddrummer14 said:


> My question is concerning overcurrent protection on a hypothetical piece of electrical equipment.
> 
> Generally speaking why and what are some instances where we as electricians protect any given piece of electrical equipment with a fuse instead of a breaker?
> 
> ...


Here is the simple answer. 

If your equipment is a 3 phase motor you would use the breaker as short circuit & ground fault protection. You then use fuses as over current protection. 

Care must be taken when sizing the protection needed. Keep in mind that after you leave, someone will change your properly sized fuse with what ever is handy.


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## oliquir (Jan 13, 2011)

Wirenuting said:


> Here is the simple answer.
> 
> If your equipment is a 3 phase motor you would use the breaker as short circuit & ground fault protection. You then use fuses as over current protection.
> 
> Care must be taken when sizing the protection needed. Keep in mind that after you leave, someone will change your properly sized fuse with what ever is handy.


isnt the fuse better for short-circuit and the breaker better for overload :001_huh:


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## Wirenuting (Sep 12, 2010)

oliquir said:


> isnt the fuse better for short-circuit and the breaker better for overload :001_huh:


Not in the motor example I gave. 
430 is hard to read at times, but the answer is still the same.


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## Big John (May 23, 2010)

Breakers are great for convenience and to help prevent single-phasing on 3 phase equipment.

Fuses are great for reliability and circuits with high available fault current.

It's also easier to get properly sized fuses for motor protection than it usually is to get the same size breakers.

-John


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## Muddrummer14 (Oct 31, 2011)

oliquir said:


> isnt the fuse better for short-circuit and the breaker better for overload :001_huh:


Are we still talking about over current protection here, or are we talking overload?


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## Muddrummer14 (Oct 31, 2011)

wildleg said:


> breakers are known to fail (miserably)
> 
> fuses can fail, but rarely fail to open. fuses in combination with properly sized overloads IMHO are much safer than breakers, although I think breakers are more reliable nowadays than ever, and for ordinary purposes (read residential) they are fine. JMHO


Ok, I get that when a fuse blows it opens the circuit then disrupting continuity and protecting said hypothetical piece of electrical equipment from overload possibilities; and from what i gather higher current fault possibilities call for higher overcurrent protection which are factually easier and cheaper to get your hands on in Fuses as oppossed to breakers. Am I interpreting this correct
Just one more question
Imho? Jmho? what does that mean?


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## dronai (Apr 11, 2011)

Muddrummer14 said:


> Ok, I get that when a fuse blows it opens the circuit then disrupting continuity and protecting said hypothetical piece of electrical equipment from overload possibilities; and from what i gather higher current fault possibilities call for higher overcurrent protection which are factually easier and cheaper to get your hands on in Fuses as oppossed to breakers. Am I interpreting this correct
> Just one more question
> Imho? Jmho? what does that mean?


In my freakin opinion, and Just my freakin opinion :whistling2: and oh yeah humble is the H


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## Muddrummer14 (Oct 31, 2011)

dronai said:


> In my freakin opinion, and Just my freakin opinion :whistling2: and oh yeah humble is the H


Nice! now i know!


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