My wife has her tubes banded, can she be pregnant?

Uh HIGHLY unlikely.

When I had mine tied/ burnt 13 years ago I had to sign a paper stating that there was a small chance that I could still get pregnant( I think that this was just a formality, just to cover the doc in case a mircale happened and the grew back together) but I had a aunt that had hers tied and they came loose and she had a couple more children. That was prob. 30 or so years ago.

I have seen somewhere in my travels around the web that one in one hundred women will repair a tube within 14 years. How long has she had her tubes tied for?

A pregnancy can happen but it could be an etopic pregnancy. Dr. Donnica Moore is a practicing OB/GYn and here is her website with that very question:

Tied Tubes and Ectopic Pregnancy - DrDonnica.com - The First Name in Women's Health

From what I have read about pregnancies after a tubal ligation, the chances are 1:400 that a woman can conceive.

Tubal ligation

My sister had her tubes tied after she had her second child then about two months after she had it done she got pregnant