There are two things here to consider.
If this a water intrusion issue, then you need to keep the water out. Did you use twist on connectors, or professional exterior connectors? Twist on will work in a pinch, but are not a long term solution. Water tight connectors sealed with rubber boots or water proofing tape is standard for professional installers.
If you can install the ground block in a box that would be the best.
As far as over voltage, that would not cause the center conductor to break. The center conductor does not break when exposed to water, it corrodes away. Usually it takes months to disintegrate, but you loose picture long before that.
If you do have some weird ground fault issue, the best thing to do is unplug your receiver and test the outlet for proper wiring. You can buy a tester for a couple bucks. If you find the outlet NOT wired correctly, remove the ground wire from your ground block and call an electrician. A satellite system cannot be grounded safely if the outlet powering the receiver is not wired correct.
There is no amp or power inserter used for satellite or off-air that can cause a cable to break. Coax is rated for 60 volts, however, any water intrusion will cause problems.