The defects listed below are ones I have commonly found in the Electrical panels of homes .
Overfusing
Overfusing is one of the most common electrical problems. Recently I have come across several instances of a 40 amp. breaker being used for a Dryer circuit with 10 AWG wire. This breaker could allow more amps to pass through it than the wire or outlet could handle.
The only way to verify the problem is to take the cover off of the electrical panel and compare the wire size to the size of the breakers or fuses. I would not recommend the homeowner take off the panel cover but rather have an electrician check for any concerns.
Double Taps
Double tapping is the term used for attaching two wires to a single breaker or fuse. Most of these terminals are not designed to accommodate two wires so a risk of a poor connection is much greater. Often you will find double tapping on a panel that is full when someone wants to add an additional circuit.
There are special breakers that are designed to hold two wires. As a home inspector I need to make a note of all double taps in my report and defer this problem to an electrician to make the final decision as to whether the installation is acceptable or not.
Openings in Panel
With the front cover installed a person should not be able to reach into the panel. The two areas I have found to be of concern are the knockouts at the sides of the panel and the breaker or fuse slots at the front. A person could insert a finger or a screw driver through these openings and electrocute themselves. There are plastic covers available for both of these situations.
Poor Access or Location
Electrical panels should be readily accessible and in an area that is appropriate. The panel should be at eye level and have adequate room in front for servicing. I have found on my inspections that panels are located in bathrooms, closets, stairwells or inside a kitchen cabinet which is inaccessible and inappropriate.