Abbreviation for demarcation point
: Interface between customer-premises equipment and network service provider equipment.
For residential telephone
or cable television
, this is a small junction box
or ground block
which delimits the threshold
between 'Your Problem
' and 'Their Problem
'. I t will usually be located near your electric utility meter
or circuit breaker panel
Before calling the utility's service technician, take a known good device to the demarcation point, unhook 'your' side's wiring and hook up the test device (nothing else) to 'their side' (You may need alligator clips). If it stills doesn't work, it's 'their problem', otherwise it's 'Your Problem', don't bother calling them unless you want to pay the utility to fix your house wiring.