Silly question from a not so hot electrician. Was going to run 12/2 with ground. While I was looking at the breakers I'll have to admit I'm stumped. Every breaker is marked 120 vac and 10ka. Would somebody tell this ignorant old farmer what that means. Are all those breakers 10amp? Even the microwave and ac and all that high amp stuff? Mine up north are all marked 15 or 20. Thanks for the input in advance.
                                         Denny

 

This may be more information than you're asking for, but here is a site:

http://www.iaei.org/magazine/2006/1...kers-mean/

Denny

KA stands for kilo-amps or in thousands of amps. 2KA breaker will trip when the load exceeds 2,000 amps.

Scooter, you are wrong. Home panelboards don't come with 2,000 amp breakers.  (Yes, "ka" does mean kilo-amps, but it is not related to the trip rating.  It is the interupting rating.) 

Denny, the 10ka designation means that it will open a fault that is up to 10,000 amps. Above that it is questionable whether it might explode but 10ka is a safe rating for just about any household service. 10ka is generally the smallest interupting rating you'll find on a breaker but it is also the most common by far.

Of course, the 120 volt rating indicates it is only to be used on either 120-240 volt, single phase panelboards (like most households have) or on 120-208 volt, three phase panelboards like you will find in many commercial buildings. It is not to be used in a 277-480 volt application.

On the handle of most household breakers you will find designations like 15, 20, 30, 40 .... This is the trip rating, in amperes, of that particular breaker. Since you are running 12/2 plus ground, the most likely breaker size will be 20 amps. It could also be used on a 15 amp breaker, but not on anything larger than 20.

Thanks guys

Excuse me for commenting on this supposedly closed thread, but in support of Bompa's answer, please see Number 3 in this thread.

Posted By bompa on 02-03-2012 08:24 PM
Scooter, you are wrong. Home panelboards don't come with 2,000 amp breakers.  (Yes, "ka" does mean kilo-amps, but it is not related to the trip rating.  It is the interupting rating.) 

Denny, the 10ka designation means that it will open a fault that is up to 10,000 amps. Above that it is questionable whether it might explode but 10ka is a safe rating for just about any household service. 10ka is generally the smallest interupting rating you'll find on a breaker but it is also the most common by far.

Of course, the 120 volt rating indicates it is only to be used on either 120-240 volt, single phase panelboards (like most households have) or on 120-208 volt, three phase panel boards like you will find in many commercial buildings. It is not to be used in a 277-480 volt application.

On the handle of most household breakers you will find designations like 15, 20, 30, 40 .... This is the trip rating, in amperes, of that particular breaker. Since you are running 12/2 plus ground, the most likely breaker size will be 20 amps. It could also be used on a 15 amp breaker, but not on anything larger than 20.

    Poor choice of word?

  Wasn't pinning anything down.

   Just what KA stands for and what it means.  

  Siemens uses the word trip.

    Siemens Sentron Series circuit breaker capable of interrupting 10000 amps at fixed instantaneous trip point of 10000 amps trips the breaker automatically

I probably should keep my mouth shut, but. Most home breakers are rated at 10kA. This is it's Arc Fault Rating.

I was working on a panel box when a lineman hit the high voltage lines when pulling a service entry cable which was probably around 30kVAC possibly even 60kVAC. In any case, the entire panel box blew up. I woke up in the hospital lucky to be alive. The bottoms of my feet had 3rd degree burns and my mouth was welded together.

Although there was no loading on the house yet, 30kVAC was greater than the breakers in this panel could handle and they apparently arced over.
I never saw the remains of the box or what the area looked like afterwards because I was out of work for quite some time.

Now just perhaps, if home breakers were rated high enough, or at least rated above the high tension line voltage, this may have not happened. But the likelihood of a service entrance coming in contact with the high tension lines is so remote that the added expense of requiring same in all homes is just not feasible.

But the 10kA rating is the point at which the breaker itself is considered SAFE and will not Arc Over or Blow Up!
It technically has nothing to do with the designed Amperage Trip parameters of the device, which is to protect the branch circuit connected to it.

There is a very good reason why high tension wires are spaced as far apart as they are, and some are suspended by very long insulators away from the metal supporting structures.

OK, now I'll go crawl back into my hole, hi hi.....

TTUL
Gary

I've seen the show when really high winds gets high tension wires swinging close enough to arc.