We have a power cable (AWG2) running underground from the main at the house to our barn about 800 feet away. Three wire cable brings two hots and a ground to the barn. One of the hots leaves the main but does not arive at the barn panel. I will need to find where the problem is. What is the best way? Are there any testers that I can use without stripping the insulation, or maybe without digging it out? Any advise will be appreciated.