All these pictures are from Oshawa and Whitby homes with Aluminum wiring.
Aluminum wiring is a form of wiring that was used from the late 1960's to the mid 1970's. The main problem with aluminum wire is at it's connection point.
All devices need to be approved for aluminum wire and need to be torqued to the proper value.
If you suspect you have aluminuim wiring call Barrett Electric Inc. to provide a free assessment.
Here are some samples of aluminum wiring I've encountered.
This is a picture of a receptacle that is designed for copper connection only. Once the connection became loose heat was generated which cause the wire to oxidize which causes more resistance and more heat. This was caught just in time!
Dangerous Aluminum Connection
Found this in an Oshawa home with Aluminum wiring. The last person working in this junction box had used the proper aluminum compound but the wrong wire connectors and this was the result.