One of the major differences between renting a space and owning it outright is who is responsible for repairs and improvements. With a commercial or residential property that one owns, they would shoulder full responsibility. However, depending on the terms of the rental contract, a landlord/property manager may need to authorize and pay for any changes or improvements. In some cases, in order to lock up a certain tenant, the landlord may need to make set changes to a property, like new wiring or network capability. These changes fall into the category of tenant improvements.
Tenant improvements present a great opportunity for electrical contractors. If you were to say, work with a landlord of an apartment or office building, this could represent a steady stream of work from a single client. Of course, you need to be able to provide a full suite of services said tenants would be interested in.