1. The crimping screws of the plugs are somewhat loose, and the connecting wires and plugs are in poor contact.
2. The root power cord of the plug is broken inside the insulating skin, which leads to a break in the work.
3. Five hole outlet is too loose or the position of the socket to offset, so that the plug contact.
4. Five hole socket lead and socket crimping wire screw is not tight, only to cause bad contact.