# AIC ratings for circut breakers

What is an AIC Rating and how is it calculated?

 CliffARobinson Posts: 1,428, Reputation: 510 Ultra Member #2 Mar 14, 2012, 01:36 PM
Quote:
 It's the Amps Interrupting Rating for the panelboard and the panel circuit breakers. This number is typically 10kA (10,000 amps) or 22kA for common panelboards and breakers and even up to 200kA for some. The AIC rating is the maximum number of surge amps that a utility can provide to the equipment and still have the equipment safely trip off.
- Source

I found a great Excel worksheet you can use free of charge that does the calculations for you as you enter information.
 tkrussell Posts: 9,673, Reputation: 3698 Senior Electrical & Lighting Expert #3 Mar 15, 2012, 04:13 AM

AIC ratings for circuit breakers are determined by the manufacturer, depending on the electrical and physical strength of the circuit brakers, and then labeled as required by Underwriters Laboratories.

The Excel calculator provided is a simple method of determining what rating the electrical equipment must meet or exceed.

For example, if the first section of calculation was performed, and the result was the available fault current at the terminals of Main Disconnect was calculated to be 12 KAIC, the electrical equipment, specifically circuit breakers, fuses, etc, at that location would need to be rated a minimum of 12 KAIC.

With this information, you then consult with the supplier of equipment and purchase equipment with a rating that meets or exceed that rating.

As an electrical system gets farther away from the Main, the calculated fault current usually gets lower, and downstream equipment may be rated lower AIC.

If a circuit breaker is installed in a system that is rated lower that the available fault current, in the event of a short circuit condition, the device can actually explode into dangerous shrapnel, along with an arc blast, capable of causing injury or death to someone close by, and fire to the surroundings, rather than simply opening normally to de-enegize the circuit.

## Check out some similar questions!

OK here is my situation I have a Siemens box in my home I'm installing GFCI breakers to bring it up to code for insurance purposes Only thing is 4 rooms in this home are for some reason wired together on 3 wires (red black and white) connected to two separate breakers (30 Amps each) (two rooms...

Circut breaker panels [ 11 Answers ]

Whenever I plug in my electric heater on one side of my house it knocks out the circut breaker.Is it possible to add another breaker panel in the box or increase the size of the panel in the box? The panels in the box are 15amps, what is the next largest size iI can increase it to?

GFCI breakers when circut lacks a ground wire. [ 1 Answers ]

Greetings, My home, built in the early 1950's, is wired with a 2 wire conducter lacking the ground wire. I believe it is 14 ga. My question is , would installing GFCI breakers provide protection from shock and fire, or would a more costly repair be in store? Thanks Sparky, Timashinkle

My circut breaker won't reset [ 2 Answers ]

Hi All you electricians out there. A light bulb just blew in my living room. Normally I would just go down to the fuse box and reset the the circut breaker. Today the circut breaker won't lift back into position. What does this mean..... I would do almost anything not to have to pay for an...