Apple Inc. announced late on Friday a voluntary recall and replacement program for the Apple USB power adapter that came with iPhone 3Gs sold in North America, Japan, and parts of South America. The company will exchange the original adapters, which carry the risk of shock, with a new, redesigned unit for free.

At issue were reports that some users were finding that the metal wall prongs on the unit were breaking off in the socket, something that could lead to an electric shock.

On its recall page, Apple said, "Users with ultracompact power adapters should immediately stop using them until they exchange them for a new, redesigned ultracompact adapter."

Apple provided this image: If your power adapter looks like this, exchange it with Apple

Until they get it replaced, Apple advised users to use the standard USB cable that also came with their iPhone 3G, or with a standard-sized Apple USB power adapter, or with a third party power adapter.

The specific adapters are those included with iPhone 3Gs in the U.S., Japan, Canada, Mexico, Colombia, Ecuador, El Salvador, Guatemala, Honduras and Peru. The same adapters were sold as a standalone accessory in Argentina, Chile, Costa Rica, and Panama.

Adapters sold in other countries throughout the world, including those in Europe, were of a different design, and are not included in this recall.

The replacement process is straightforward: You can order a replacement via a Web form on Apple’s Web site, or you can take it to an Apple Store. The replacements will be available on October 10th, 2008. You can get more details on Apple’s recall Web page.