These requirements cover insulating cleats@ knobs@ and tubes for the support of conductors of open wiring or concealed knob and tube wiring of circuits involving potentials of 600 volts or less@ in accordance with the National Electrical Code@ NFPA 70. These requirements do not cover split knobs and multiple-wire cleats for conductors larger than No. 4 AWG (21.2 mm?)@ solid knobs for conductors larger than No. 4/0 AWG (107.2 mm?)@ knobs not intended for over-surface wiring@ or tubes having an internal diameter greater than 2-1/2 inches (63.5 mm). A product that contains features@ characteristics@ components@ materials@ or systems new or different from those covered by the requirements in this standard@ and that involve a risk of fire@ electric shock@ or injury to persons@ shall be evaluated using the appropriate additional component and end-product requirements to determine that the level of safety as originally anticipated by the intent of this standard is maintained. A product whose features@ characteristics@ components@ materials@ or systems conflict with specific requirements or provisions of this standard shall not be judged to comply with this standard. Where appropriate@ revision of requirements shall be proposed and adopted in conformance with the methods employed for development@ revision@ and implementation of this standard. *1.3 revised July 28@ 1998*