On the left you can see some silver colored wiring. This is aluminum wiring and is highly dangerous. Aluminum wiring generally is found in homes built between 1965 and 1973. I have personally seen smoke and sparks coming from panel boxes due to loose connections and have seen homes that have had fires. Repairs are generally quite expensive. Even electricians are not always knowledgeable and may minimize the safety hazards. An excellent publication is available from the US Consumer Product Safety Commission Click on the link to learn more.