Here is a thread that got a little heated but not too bad. It discusses the pros and cons of an electric wire and also the buried type.
Everyone here knows that I use and electric wire and it works just fine in our home. It hasn't worked in probably a few months and isn't even plugged in anymore but knowing it is there has kept Rebel in the backyard where he belongs.
This thread is 9 pages long but is a good read...
http://www.yorkietalk.com/forums/sho...light=electric