It could be many things. 1  Gather facts. 2  Rule out equipment... 3  Back to gathering facts... 4  Call Comcast.  Good 1  luck. Have your problems always existed (with your current installation/configuration)?  When speaking with anyone...
A maximum-phase system is the opposite of a minimum phase system. A causal and stable LTI system is a maximum-phase system if its inverse is causal and unstable. That is, 1  The zeros of the discrete-time system are outside the unit circle.
For ungrounded systems, the greatest voltage between the given conductor and any other circuit conductor is also the phase-to-ground voltage. On a 480V, three-phase, 3-wire, ungrounded delta system, the phase-to-phase voltage is 480V. Based on the definition, this is also the phase-to-ground voltage for this system.