breaker switch*


  #1  
Old 05-28-02, 04:03 AM
damn*thats*hot
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Question breaker switch*

on the breaker switch it reads * 10,000 ALC *... what does this mean.
i flipped it off to see what it was "'hooked" up to i, and it was just about everything.
i haven't had any problems, just wandering
 
  #2  
Old 05-28-02, 12:08 PM
Wgoodrich
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That number is called an interupting rating. This means that your breaker will trip if a short circuit sudden impact load exceed 10,000.

A breaker trips for two reasons first a breaker trips if a wire it is protecting exceeds in amp load the maximum ampacity of that conductor to avod fires which protects buildings.

Often times if you have a larger amp rated branch circuit suddenly obtain a dead short either phase to phase or phase to ground you will hear a hum. This hum represents one bunch of current flowing where it is not supposed to be flowing. The equipment grounding conductor completes a circuit from your noncurrent carrying metal parts all through your house. When this hum is sounding off either two hot phases are shorted together, or a hot and a neutral conductor is shorted together or a hot is touching a metal frame of an appliance etc. When this happens one big pile of current suddenly flows. If that hot wire is shorted to say a plumbing pipe the hot current flows from your hot conductor through that metal plumbing to an equipment grounding conductor that is connected to you electrical panel's grounding bar. This causes that pile of current to pass through that breaker causing it to trip due to that second reason called the interupting rating of your breaker.

This interuppting rating is rather high to avoid an unneccessary interupption of power when a motor starts, etc. Causing what is called a normal inrush of electricity when a motor startes etc. This would be normal. Yet a shorted circuit would create current much higher than that the interuppting rating is supposed to make the breaker give in these impact loads of amps get high enough.

Normally the interuppting rating is set below the capacity of hte service transformer so that the breaker will trip due to interupting rating before the transformer is damage or the wires start showing damage.

A wire can take a huge amount of current in short bursts. The interupting rating makes sure that it remains only SHORT burst of load allowing that breaker to trip before damage to the transformer or the conductors in your home has a chance to heat up to a level that would cause damage to that equipment due to that heat if over a sustained period of time.

Hope this helps

Wg
 
  #3  
Old 05-28-02, 12:47 PM
damn*thats*hot
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wgoodrich

thanx for the info. good buddy...
 
  #4  
Old 05-28-02, 01:37 PM
resqcapt19
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wg,
I think that 10,000 AIC on the breaker indicates the maximum amount of fault current that the breaker can safely interrupt. A breaker should never be installed on a system where the maximum available fault current exceeds the AIC rating. This rating has nothing to do with the time current trip curves of the breaker.
Don(resqcapt19)
 
  #5  
Old 05-28-02, 05:08 PM
Wgoodrich
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resqcapt19, thought that was what I was saying. Maybe it wasn't properly worded to understand what I was saying.

I just tried to show how a breaker trips by two reasons as well as show the Utility equipment rating dictates the AIC rating. If you have a 10,000 rating on the utility transformer you can melt down that Utility equipment if you have a 20,000 rated breaker in the structure if it does not trip on the short circuit operation properly.

Must have rambled too much and confused the issue.

Wg
 
  #6  
Old 05-29-02, 04:33 PM
resqcapt19
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wg,

The breaker has nothing to do with the protection of the utility transformer. The breaker AIC or AIR rating must always exceed the fault current that the utility can provide. There is no problem using a 22,000 or even a 65,000 AIC rated breaker on a system where the utility transformer can only source 10,000 amps of fault current. Look at the rating of time delay fuses, they are rated at 200,000 amps. These are not trip points and have absolutely nothing to do with the time/current trip curves. These are the values that the breaker can safely open up. If you apply a 10,000 amp AIC breaker on a system that has a 22,000 amp fault current and there if a fault, it is very likely that the breaker will explode when it tries to clear the fault.

Don(resqcapt19)
 
  #7  
Old 05-29-02, 06:14 PM
Wgoodrich
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resqcapt19, what you said is correct. What I said was exactly backwards. When I said you could have a melt down the melt down would be where the breaker interrupting rating is smaller than the rating of of the serving utility. Actually the intent is to protect the equipment in the structure not the utility equipment located outside. For some reason I am saying certain things backwards on this post. I think it one way and discribe it backwards. Must have my brain somewhere else other than on my fingers.

Wg
 
  #8  
Old 05-29-02, 07:07 PM
M
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Perhaps you have your hot and neutral reversed somewhere between your brain and your fingers....
 
  #9  
Old 05-30-02, 11:10 AM
Wgoodrich
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Nope Mike I think I may have had a case of low voltage to the brain. Maybe I was worked too hard and put up wet too many times over the years. I'll see if I can charge my batteries in a day or two. Ha Ha.

Wg
 
 

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