Wis. Stat. § 196.61
A public utility may not demand, charge, collect or receive from any person less compensation for any service rendered or to be rendered by the public utility in return for the furnishing by that person of any part of the facilities incident to the service. This section may not be construed to prohibit any public utility from renting any facility relating to the production, transmission, delivery or furnishing of heat, light, water, telecommunications service or power and from paying a reasonable rental for the facility. This section may not be construed to require any public utility to furnish any part of any appliance which is at the premises of any consumer, except meters and appliances for measurements of any product or service, unless the commission orders otherwise.
Wis. Stat. § 196.61