Difference in MCCB.

One will withstand a prospective short-circuit current [PSC] of "35kA" and the other a PSC of "25kA>".

Really now! You got to be kidding. It's 10kA.

This really is a clear case of acronym abuse. The Michigan Community College Biologists will be baffled to hear that their acronym is used in such a cryptic fashion.

If the OP is instead referring to Molded Case Circuit Breakers rated for a hold current of 63 amperes and an interrupt capability of 35kA or 25kA, then I say put the screw driver down, close the door and walk away from the electric distribution box. If the manufacturer's data sheet does not use terms that you understand then you are likely not qualified to be working on this lethal equipment. The life you save may not be your own.

If instead you want the Mitchell County Conservation Board and want an explanation of their by laws 35KA and 25 KA, well you better contact them.

Possible to explain after studying the two MCCBs side-by-side. Costs in India $50 per hour, should take ≈ 16 hours of study, ≈ $ 750 ≈ Rs. 35000. That is what i get paid.

However, if you are working for some company, and want to enrich your own knowledge, there are many experts here on CR4 (some of them are worth $1000 per hour, believe me!) who will jump in to help you if you show some initiative to learn. We will not spoon-feed anyone.

1. You must register, with some details, where you are, what age/experience... so on. i for one, will not enlighten a complete stranger.

2. You need to analyse what is an MCCB, why it is able to break 10kA, 25kA, 35kA....200kA. We need to know that you can investigate. Then we will help.

3. You need to post this in Electrical Engineering, not here.

Am i harsh ? If so, apologies. Better you become a better engineer than i become a nicer person.

Good luck.