[HomeBrew] AC vs DC Breakers

[James Kearman]

rbethman wrote:
> Your site would seem to defeat your statement.
>
> The same breaker is used for AC or DC.
>
> I submit that a 120VAC 30A circuit breaker WILL interrupt 12VDC 30A.
>
> The arc distance built into the breaker is far more than adequate for 12VDC.

A breaker that can safely handle dc should be able to handle the 
equivalent ac current, for reasons stated in my original email.

The opposite is not necessarily true, as there is no zero crossing with 
dc -- it's continuous current by definition. Dc breakers have larger 
contact spacings or internal designs to inhibit the arc. It stands to 
reason they'd work fine on ac.

 An ac breaker may work fine on dc 99% of the time. As I mentioned, 
however, _under short-circuit conditions_, the arc may not extinguish. 
Then either the source or load blows up or the breaker catches fire. 
Guess how I know that? Given that the function of a circuit breaker is 
protection, pay the money and use one designed for the task.

73,

Jim, KR1S
http://qrp.kearman.com/