Why do you think that the cable connection in the house becomes dangerous during lightning?
A cloud-to-ground lightning bolt's main objective is to find the path of least resistance from the cloud to deep into the ground. Most houses are filled with many potential routes for lightning to follow in its journey. This can include gas and water pipes, electric lines, phone lines, cable TV/internet lines, gutters, downspouts, metal window frames - anything conductive in a house is for the lightning to follow. Lightning doesn't need conductive objects to reach the ground, however - it's just forged its way through miles of air, so conductive objects in a house are a mere 'convenience' that it will use if they are available.
Lightning passing through a house will often 'branch' and utilize more than one path to ground at a time. It can also jump through the air from one conductive path to another in what is called a side flash. For example, lightning may first connect to electric lines in the attic of a house, then jump to better-grounded water pipes on the first or second floor. Lightning can connect to gutters, then jump to a window frame as a 'stepping stone' to the electrical system or water pipes. All or parts of bolts have been seen jumping from wall outlets to sink faucets and even across rooms!
