It all depends the spread which is the rate added by each bank.

HELOC or some other line of credit rates all have two components.  One is a variable rate called 'Prime Rate' and the other is a fixed rate to be added on to the Prime rate called 'Spread'.  You can do nothing about the Prime rate since it is determined by Federal Reserve Bank.  But you can shop around to find the lowest spread offered by banks.  

Bottomline, you don't have to deal with all these rates.  Just shop around to get lowest HELOC rate.  The lower the HELOC rate, the lower the spread.