Last year, my beeyard fence of 4  barbed wire (2 hot) was torn through
by bear(s).
 
I have replaced it with  8 wire high tensile with about 6" spacing, (3
hot) topped with a single barbed wire (also hot).  Final height is about
60".  I use a good quality charger with a face meter which tells you if
you are having contact or shortage problems.  I also use toothpicks to
attach bacon to the nose high (the bear's nose) hot wire.  The bacon
must be replaced frequently as the birds (titmice) eat it.
 
So far, so good but we are just now beginning bear damage season here in
NE Pennsylvania.  Unfortunately, one doesn't usually know if your fence
works, only when it doesn't.
 
Burns