Proper grounding of the cable outside is very important. If the cable is not grounded, voltage backfeed and melted connecters could result. Wether there is a problem
with the equiptment inside the house (such as bad tv's) or something happens like a lightning strike...having a good solid ground can prevent damage to other devices.
Quite often, problems are created from poor home electrical wiring or poor house grounding. Sometimes, flickering lights or damage to other electrical devices around
the home (like air conditioner compressors) can be a sign of poor house grounding. Usually when sparks occur with coax cable, it means a grounding problem somewhere
(likely in the home electrical and not the cable itself). There should never be any voltage to speak of on the cable. What is on the cable is measured in microvolts.
Ground blocks like this should be used:
The cable should be grounded to the electrical meter box or possibly a breaker box attached to the meter. Grounding rods are also acceptable. NEVER ground to a water pipe.
Most apartment buildings and many townhomes are grounded in the MDU box where the cable taps are located.
Coax with a smaller wire attached is referred to as 'messenger cable' and is for aerial (or over head) use. This extra wire is NOT for grounding. It is for taking tension
of the line so the coax itself doesn't get stretched. This may be used as a ground for satellite equiptment but NOT for cable.