The issue is that the new Lightning sync cable that comes with the iPhone 5 is very brittle. I have returned my original cable after it started working within 1 week of purchase to Best Buy where I purchased my iPhone 5. The new cable that I received again stopped working. The first cable sheathing had a cut in it. The second cable came loose at the adapter. Both cables stay in the same place at all times and is never exposed to anything that would cause these issues.
In my honest opinion the new Apple lightning adapters are Lemons and Apple should pony up and replace all of the bad adapters with a new revision of cables. I am not sure how this got through QA, but I would imagine it has something to do with where these products are being mass produced.
I purchased a new adapter from Brookstone that has a much more sturdy sync cable and power adapter. This new charger has been working like a charm, and in fact is much quicker to charge my phone.
Alan Simpson, I understand the concept of "why buy a new cable if yours is under warranty", but the problem is this. Why keep making trips to the Apple Store to get a new cable when in fact the new cable is just as bad as the cable you have. Who has the time to keep going back to replace cables.. This reminds me of the exploding batteries that Dell had some time ago (much different outcome, but same QA type of issue), and Dell actually had a plan to resolve the issue. It doesn't seem that Apple has any such plan to date, and have caused a lot of people issues with the new phones. Don't get me wrong, I love Apple products (I have 2 Macbook Pro's, 2 iphone 4S, 2 Ipads, Apple TV, and 2 iphone 5's) but this is something that needs to be brought to Apples attention.
I am even contemplating reaching out to the Attorney General's office in my state and making a formal complaint. I would advise others who have gone through multiple Apple branded lightning sync cables and charging adaptors.