And "own home" has a lot of meanings.
As I'm sure Cacher Chick knows, in the Land of Cheese, state law says that it's illegal to do any plumbing, even on property that you own, except: (1) Farmers working on their own buildings; and (2) In (A) a one family dwelling that (B) you own and (C) you actually occupy as your primary residence. Plumbing on everything else, including multi-family dwellings, vacation cottages, rental homes, etc., has to be done by a licensed plumber. And of course the stuff has to be to code. And in Wisconsin, you can't do plumbing on a house you are building for yourself.
In Illinois, the actual law is as follows; it is the exception to the otherwise-stated rule that you can't plan, install, etc., plumbing without a license:
"Nothing herein contained shall prohibit the owner occupant or lessee occupant of a single family residence, or the owner of a single family residence under construction for his or her occupancy, from planning, installing, altering or repairing the plumbing system of such residence, provided that (i) such plumbing shall comply with the minimum standards for plumbing contained in the Illinois State Plumbing Code, and shall be subject to inspection by the Department or the local governmental unit if it retains a licensed plumber as an inspector; and (ii) such owner, owner occupant or lessee occupant shall not employ other than a plumber licensed pursuant to this Act to assist him or her.
For purposes of this subsection, a person shall be considered an "occupant" if and only if he or she has taken possession of and is living in the premises as his or her bona fide sole and exclusive residence, or, in the case of an owner of a single family residence under construction for his or her occupancy, he or she expects to take possession of and live in the premises as his or her bona fide sole and exclusive residence, and he or she has a current intention to live in such premises as his or her bona fide sole and exclusive residence for a period of not less than 6 months after the completion of the plumbing work performed pursuant to the authorization of this subsection, or, in the case of an owner of a single family residence under construction for his or her occupancy, for a period of not less than 6 months after the completion of construction of the residence. Failure to possess and live in the premises as a sole and exclusive residence for a period of 6 months or more shall create a rebuttable presumption of a lack of such intention."
So, simply-put, it's similar conceptually to Wisconsin, except a lessee can do plumbing, and you can do plumbing in a one-family home you are building for yourself to be your exclusive residence, but you actually have to live there or it will be assumed that you always intended to flip it. The danger of abuse of this exception is probably why Wisconsin bans the practice outright. And Illinois makes clear that you can't hire people to help you other than a licensed plumber. While that probably technically means that you can't get your brother-in-law to help you, the real purpose of that prohibition is probably to keep you from backdooring the work of handi-hacks by saying that you are doing the plumbing and they are "helping".