This standard provides for the application of impedance heating systems for steel or steel alloy pipe and equipment. It provides recommendations for design@ installation@ maintenance@ and repair of these systems in general industry applications. This standard applies to impedance heating systems intended to be installed in ordinary and hazardous locations with explosive atmospheres. The hazardous locations include the following: - In Canada: Zone 2; Zone 22; or Class I@ Division 2; Class II@ Division 2; Class III@ Division 2 as described in CSA C22.1; and - In the USA: Class I@ Zone 2; Zone 22; or Class I@ Division 2; Class II@ Division 2; Class III@ Division 2 as described in the NEC. This standard@ when used with other recognized codes and standards@ is intended to cover impedance heating systems in their entirety@ including system design@ specification@ installation@ operation@ testing commissioning@ and maintenance. This document also addresses the following associated systems that are important to the performance of impedance heating systems: a) Thermal insulation systems; b) Electric power supply systems; c) Electric grounding systems; and d) Control and monitoring systems. Purpose This standard is intended to aid the user in specifying@ installing@ operating@ testing during commissioning@ and maintaining impedance heating systems that: a) Maintain design temperature; b) Provide electrical@ thermal@ and mechanical durability and reliability; and c) Reduce hazards to the user and the surroundings. Design information@ selection parameters@ and data in this standard are not intended to provide a complete design primer for impedance heating systems. The information presented provides guidelines for the following: a) Selecting the optimum impedance heating system design; b) Establishing design criteria and constraints for the heated pipeline or equipment to help ensure system compatibility; c) Preparing specifications to obtain quotations for impedance heating systems; and d) Developing information on installation@ operation@ testing@ commissioning@ and maintenance of the impedance heating system.