Do I need license to do electrical work in any residential home?
The general answer in most parts of the US is YES. The exceptions, generally, are:


Work on your own home
Limited "handyman" work - e.g., replacing receptacles or light fixtures, but not replacing breaker panels (with the line somewhere in between)


However, the specifics vary tremendously around the country (and even more around the world). Some places require a license to do just about anything. Others are far more flexible.

The requirements to get a license also vary quite a bit. Typically some combination of experience (which you have) and knowledge test (of code &amp; best practices).