Tip- Only trained professionals should perform the internal inspection process. Locate the electrical panel. Carefully remove the cover making sure not to come in contact with any live wires. Look at the main wires powering the panel and wires connecting to the breakers to see if they appear to be secured and the insulation is intact and not melted/discolored. Melted/discolored insulation is an indication of wires having too much power pulled through them or arcing is occurring which can be fire hazards. Aluminum wires should have visible antioxidant grease on the exposed wire. The grease helps prevent corrosion which can lead to arcing and can be a fire hazard. Main power lugs should only have main power wires connected to them. Wires powering subpanels or air conditioners are commonly powered from main lugs but should be ran off of appropriate sized breakers. Check to make sure all breaker screws have no more than one wire attached to them. Multiple wires connected to one screw can cause wires to be loose and arc which can be a fire hazard. White branch wire connected to a breaker should be marked with red or black on each end of the wire (in breaker box and at outlet/fixture) to indicate it is used as a power wire instead of a neutral to help prevent electric shock. Neutral (white) wires connected to buss bar are not allowed to be doubled in one screw hole. Low voltage transformers are not allowed to be mounted inside high voltage panels.