ANSI live-line categories

The three categories for different types of insulated aerial devices are:

Category A requires the design and manufacture to accommodate a method of work called ‘live line-bare hand' as it is practiced in the US and other parts of North America (Canada's CSA C225 standard and ANSI A92.2 were harmonized in the 2000 and 2001 editions). Devices produced under this Category must include components specifically required to meet work practices that are required by the US government's safety organization, OSHA. (In particular, boom current monitoring when a worker is bonded to an energized conductor during work; this is when the insulating boom is used as the primary protection from electrocution). One very important design component of a Category A aerial is that all conductive components at the platform end of the aerial device must be bonded together, placing all these components at the same electrical potential.

Category B is a device manufactured with components that enable the user to determine electric current levels (leakage) over the length of the boom. This allows for periodic testing or monitoring of currents should the boom be used as primary dielectric protection (the A92.2 standard allows for a Category B device to be converted to Category A). The key thing here is that a Category B device doesn't need all the conductive components at the boom-tip to be bonded together. Category B devices are mostly used to perform work on live lines either by using insulating gloves (gloving) and other ‘cover up' materials, or insulating tools (hot sticking) as primary insulation.

Category C means an insulating device that is manufactured without components to enable users to monitor boom currents and where dielectric testing is conducted without monitoring individual components of the insulating structure (boom). Category C devices are used to perform work on live lines either by using insulating gloves (gloving) and other ‘cover up' materials, or insulating tools (hot sticking) as primary insulation.