Work performed by a person that is licensed as a mechanical contractor
in a classification described in section MCLA 339.5807(2)(a), (b),
(d), (e), and (f), a person that is licensed as a plumbing contractor
under Article 11, and employees of those persons, while performing
maintenance, service, repair, replacement, alteration, modification,
reconstruction, or upgrading of control wiring circuits and electrical
component parts in existing mechanical systems defined in the Michigan
mechanical code and the Michigan plumbing code, including, but not
limited to, energy management systems, relays and controls on boilers,
water heaters, furnaces, air conditioning compressors and condensers,
fan controls, thermostats and sensors, and all interconnecting wiring
associated with the mechanical systems in buildings that are on the
load side of the unit disconnect, that is located on or immediately
adjacent to the equipment, except for life safety systems wiring.