Never worked with 208V!

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From qcroanoke's post the difffence nin the breakers is the AIC rating with deals with fault current. With "fault current" you are entering an entirely different world :D
Your engineering folks should be able to give you some of the basics and/or you can search "fault current" on this site and gain a lot of insight. It normally takes extensive study or training to master the concept.
Although it puts you in a position of trusting someone who previously designed/selected the panel you are working with, you are relatively safe matching the existing breakers.
 
Forgive my bluntness, but your post #13 and #23 show an almost complete misunderstanding of the relevance of fault-current ratings in this situation.
I do not want to discourage your participation in the Forum and encourage to continue to ask questions, but at the same time recognize your limitations.
 
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augie47 said:
Forgive my bluntness, but your post #13 and #23 show an almost complete misunderstanding of the relevance of fault-current ratings in this situation.
I do not want to discourage your participation in the Forum and encourage to continue to ask questions, but at the same time recognize your limitations.
Click to expand...

I am here to learn!

I have no peers to work with and my engineer is swamped. This is my first attempt at using a forum. I appreciate everyone's working to keep only professionals in the forum. I will address my limitations when I find out what they are. I won't know my limits until I test my knowledge. I will now be reviewing AIC.

Thank You!
 
blupony96 said:
I am here to learn!

I have no peers to work with and my engineer is swamped. This is my first attempt at using a forum. I appreciate everyone's working to keep only professionals in the forum. I will address my limitations when I find out what they are. I won't know my limits until I test my knowledge. I will now be reviewing AIC.

Thank You!
Click to expand...
once you have a decent understand, teach me :D
 
Understand the acronyms.
AIC = Amps Interrupting Capacity: the amount of current a protective device has been tested to safely interrupt. This value cannot be determined in the field. It is based on the manufacture of the device. It is possible to have AIC series-combinations ratings based on testing of specific devices.
SCCR = Short Circuit Current Rating: the amount of current equipment can withstand while waiting for a protective device to operate. Each piece of equipment has different methods and tests used to determine their rating. UL508A is a commonly referenced standard for field determinations, although it only applies to control panels built to the standard.
SCA = Short Circuit Amps: this is the amount of current that will flow through a short circuit. This value is calculated based on the actual installed equipment and conductor impedances. Finding information on the source of short circuit currents (e.g. utility data) is usually the most difficult portion of determining an SCA

NEC 110.9 requires protective devices to be chosen such that their AIC is greater than the calculated SCA.
NEC 110.10 requires equipment to be chosen such that its SCCR is greater than the calculated SCA.

Chosing an AIC without knowing the target SCA is kind of like choosing conductors without knowing the load and any applicable deratings.
 
Installing a 120/240 breaker on 120/208 service is perfectly fine. It's voltage rating supersedes. Cheers :-D
 
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