While inspecting houses I often find problems in the main electrical service panel.  The most common for me is that the breaker/fuse for the A/C has undersized wires or that the breaker amperage is too large.  But I also see on other breakers/fuses where the wire sizing for some breakers is too small.  So what does this mean?

Every size breaker/fuse has a certain minimum wire size that is needed.  If the wire size is too large for the breaker/fuse, that's not a problem, assuming the breaker size is correct.  However, if the wire size is too small the wire can scorch, melt or cause a fire.  Obviously that's a problem.  Here's an example of some wire sizes and the maximum amperage they can handle:

The problem is that someone can know the written requirements for breakers/fuses, but if they're not familiar with what they actually look like it does no good.  There are so many wires in a main electrical panel that one can easily get confused and not notice if the improper wire size is present, look at the picture below.  That's where you need a professional home inspector or electrician.

Exterior A/C condensers have data plates on them that indicate the maximum and minimum breaker/fuse sizes.  When the breaker/fuse is checked in the main panel (assuming someone labeled the breaker/fuse, which doesn't always happen) or A/C disconnect, the breaker/fuse size is many times either too large or the wire sizing is too small.  Why is this?  I really can't say.  One reason is that was the only size breaker they had left in their truck at the end of the day... so why not use it and save a trip to the hardware store?  Poor excuse of course.  The main electrical panel also should have a label that indicates the maximum service size it can handle.  The other breakers do not have official labels, so a home inspector checks to make sure the wiring is correct for that size breaker.

I hope this gives you a little more information about a home and about home inspections.