Will standard mcbs work on 12v AC?

True if you go by the letter of the standards, but not if you actually ask the electrons - clearly any MCB that introduced  even a fraction of a volt drop resistively would soon fail, as the consumer unit is was in would catch fire - in this case a 10A MCB dropping 1 volt at 10A would be dissipating 10W - in reality dissipation has to be far less than that.


And to have such a voltage drop inductively in that volume would requires a closed magnetic circuit, but the trip has to be such that the magnetic circuit does not form a complete iron 'loop' until after the contacts have de-latched, or there would be no force to actuate the mechanism -  if you like to think of it that way, it is the desire of the system to seek a low energy state, that causes it to be favourable for the magnetic parts to move together.

Yes you are may be using them outside their guaranteed range but only because the makers never foresaw this case and never tested for it.

However, in the interests of size and sanity, I'd still suggest looking at automotive fusing techniques first, but because this is the voltage and current range they are intended for, and they are smaller and neater, and are clearly not going to be confused with mains,  not because of the MCB maker's data.


regards,

Mike.

example - takes the medium sized blade fuses.

True if you go by the letter of the standards, but not if you actually ask the electrons - clearly any MCB that introduced  even a fraction of a volt drop resistively would soon fail, as the consumer unit is was in would catch fire - in this case a 10A MCB dropping 1 volt at 10A would be dissipating 10W - in reality dissipation has to be far less than that.


And to have such a voltage drop inductively in that volume would requires a closed magnetic circuit, but the trip has to be such that the magnetic circuit does not form a complete iron 'loop' until after the contacts have de-latched, or there would be no force to actuate the mechanism -  if you like to think of it that way, it is the desire of the system to seek a low energy state, that causes it to be favourable for the magnetic parts to move together.

Yes you are may be using them outside their guaranteed range but only because the makers never foresaw this case and never tested for it.

However, in the interests of size and sanity, I'd still suggest looking at automotive fusing techniques first, but because this is the voltage and current range they are intended for, and they are smaller and neater, and are clearly not going to be confused with mains,  not because of the MCB maker's data.


regards,

Mike.

example - takes the medium sized blade fuses.