Exclusion(s): Establishments primarily engaged in:

*constructing power and communication transmission lines (23713, Power and Communication Line and Related Structures Construction); *installing and maintaining telecommunications lines by telecommunications companies (517, Telecommunications); and *burglar and fire alarm installation combined with sales, maintenance, or monitoring services (561621, Security Systems Services (except Locksmiths)).

Exclusion(s): Establishments primarily engaged in:

*installing electrical controls for HVAC systems (23821, Electrical Contractors and Other Wiring Installation Contractors); and *duct cleaning (561791, Duct and Chimney Cleaning Services).