When you cut through the cable, sometimes an excess current flows, which blows the fuse and may burn the contacts on the switch or other device in the switch. When the cable is renewed or repaired the dirty contacts in the switch may prevent the m/c from working. In regard to the previous answer, there is a difference between voltage and current. Voltage is pressure and current is flow. You may have voltage from the Line (Red) terminal all the way up to the point of the open circuit which may be the dirty connection on the neutral contacts of the switch. The switch has both Line & Neutral contacts.
Jeff, November 2008
