Loose Connections in the Electrical Panel
Loose connections can cause problems such as lights not turning on fully or at all; outlets may lose power; power bills could be more than they should be. Loose hot, neutral or ground wires in the electrical panel are a common problem. In this case it is an easy fix being that all of the connections are in the same area and are accessible. To check for loose connections in the electrical panel, turn off the main breaker and drag a screwdriver over all of the wire connections and watch for any movement of the wire. If its secured properly the wire won't move when touched by the screwdriver.
Loose Connections in the Electrical Boxes or Fixtures
A more difficult problem to solve is loose connections inside of the electrical boxes themselves. Because all of the electrical boxes have devices installed in them --- outlets, lights or switches --- you can't see inside of the box to check for loose connections. The only way you will know that there is a loose connection is when a problem shows up. For example, if you turn on a light and it flickers on and off. The problem could be in one of the switch boxes, the light fixture box or the electrical panel. Loose connections lead to heat, heat leads to arcing and arcing leads to fire.
Lack of Antioxidant on Aluminum Wiring
Antioxidant is supposed to be applied to any connection with aluminum wires per UL recommendation to the NEC. The NEC doesn't actually require it but it is something inspectors look for. If none is used on a connection, given time the wire connection can corrode and oxidize breaking the connection or causing it to arc, running up your power bill.
When two different types of metal are connected together, oxidation can occur. Oxidation is most commonly seen on the negative and positive terminals of a car battery's connections. The white-greenish powder that forms on the wires and posts is oxidation. The same happens to aluminum wire connections without antioxidant.
Worn Out or Damaged Electrical Panels
After many years of use, an electrical panel can become worn out. The main breaker on older electrical panels can eventually lose its grip on the buses inside of the panel where the breaker makes contact. When this happens, it begins to arc to complete the circuit; in the process it heats up both the buses and the breaker. Eventually the arching can burn through the bus completely and cause the breaker to lose connection to one or both legs of power being fed from the utility company.
If any arching or fizzing sounds are coming from your electrical panel, it is a good idea to have an electrician check it out and perhaps save you from having to replace the whole panel and bus work.
A stray current is when current takes an unintended path; ground faults are a common example of this. Any wire, hot or neutral, that makes contact with the ground wire or any conductive material is considered a ground fault. These can happen inside of electrical boxes or anywhere along the run coming from the electrical panel.
If a wire is installed without considering where it is routed, such as across a nail plate or in pinch points of trusses, the wire and insulation could be damaged and create a short or fault. Ground faults are a major cause of electrical shock. When a neutral comes into contact with a ground or metal enclosure, the uninsulated ground or the enclosure itself can become energized and will shock you if touched.