This is good informationand thought I would share.

I also ordered a C/B for $75 because my breaker is defiantly bad. How do I know? I let all the smoke out of it. When I get the new part I will be performing this test.

At 06:26 PM 11/8/2011 -0800, you wrote:
(1) Part #: AB3-X0-00-349-3D1-C Quantity: 1 Mfgr: Carlingswitch

This is a 30A AC Single Throw, Triple Pole breaker for my A/C distribution panel on my boat. If this part is no longer available is there a suitable sub?
Thanks for your inquiry, PLEASE READ...
The breaker you're inquiring about is specific to the marine industry, typically as a 30 amp AC shore power main. Hundreds of inquiries each year, 90% of them false alarms have spawned this blanket response. If your looking to replace a part that is physically broken, burned, submerged (God forbid), spindled, or mutilated, please skip to the last paragraph and place an order through the link provided, complete with any fitting rant about how I'm an idiot for questioning you in the first place - one my old lady hasn't regaled me with already would be nice - and accept my apologies for the faux pas.
Versions of this part are made primarily by Airpax and Carling Technologies and can be either 2 or 3 poles, usually with a toggle on only one pole. The breaker functions similar to a household GFI breaker in that it has a ground tripping component. Unlike a GFI breaker, however, it's not designed to protect you but rather your boat from the effects of AC power on the bonding system which can wipe out underwater metal, not to mention the odd swimmer in short order. Any AC voltage present on the bonding system will trip this breaker in well under a second, 70 ms to be precise. If you're getting nuisance or unexplained tripping, odds are the breaker is just doing it's job. We recommend you test for voltage to ground by either removing the neutral (green) inputs from the breaker to see if the symptoms disappear, or with a meter. Our legal department recommends you put everything back exactly as you found it immediately after said test. Our legal department has no sense of adventure.
Should the problem "disappear" with the ground disconnected from the breaker the issue becomes finding the source. Unfortunately this is rarely an easy process. A meter in place of the breaker's voltage coil (green wires to the meter) will make it easier to isolate a side of the boat, outlet, or appliance. Frequent culprits of low level shorts are compressor loads (refrig, ice maker, air cond) as the surges they require at start up tend to age things faster than uncompressed loads, but they're by no means the only possibility. Battery chargers are another frequent culprit, even night-lites. The list goes on. In addition, marina grounds are sometimes common to several slips, meaning the problem could be your neighbors, though it's rare. Discovering the culprit can be a multi weekend - multi beer affair. Hang in there. These cases often give experienced electricians fits.
Having said all that, we try to keep a few of the 3 pole black toggle versions on hand at all times. They're $75 each and if you elect to buy one you get to keep it (not returnable)....since you've been "enlightened". Order them at our secure server using "marine 3P per letter" as the part number.
Hope this helps. Best regards.

Gregg Porter
POCO Sales, Inc.