Hello,i need some help.I want to install a 70amp subpanel in my detached garage,and i want to bring it from my main panel.I want to install a 70amp double pole breaker in the main to feed the subpanel.The main is a 30 space 150amp panel and there are 6-15amp...7-20amp...3-30amp...1-40amp...and 1-50amp breakers there now. Do i have enough left to put in a 70amp.I plan on using #4/3 with a grounding rod at the subpanel.It's about a 60ft.run.