15.13.1 The high-voltage circuits shall be designed so that any discharge produced when the charging electrodes of the bed are approached or contacted by a grounded object cannot produce a spark that is capable of igniting the most hazardous powder–air mixture likely to be encountered and so that they cannot result in a shock hazard. 15.13.2 Transformers, power packs, control apparatus, and all other electrical portions of the equipment, with the exception of the charging electrodes and their connections to the power supply, shall be located outside the area classified as hazardous or otherwise shall conform to the requirements of Section 15.7. 15.13.3 All electrically conductive objects within the powder coating area, except those objects required by the process to be at high voltage, shall be electrically connected to ground with a resistance of not more than 106 ohms (1 megohm). This requirement shall also apply to any personnel who might enter the area. The powder coating equipment shall carry a prominent, permanently installed warning regarding the necessity for grounding these objects. 15.13.4 Highly resistive objects (i.e., surface conductivity between 108 and 1011 ohms per square) that exhibit a surface voltage below 2500 volts, as measured using a nonloading kilovoltmeter and when subjected to coronal current not less than that expected in the application process shall be considered adequately grounded. 15.13.5 Objects or material being coated shall be maintained in electrical contact [less than 106 ohms (1 megohm)] with the conveyor or other support to ensure grounding. Hangers shall be cleaned to ensure effective contact. Areas of contact shall be sharp points or knife edges where possible. 15.13.6 The electrical equipment and compressed air supplies shall be interlocked with the ventilation system so that the equipment cannot be operated unless the ventilation fans are in operation.
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