As manufacturers on the U.S. eastern seaboard recover from Hurricane Irene, it’s important to follow NEMA guidelines to ensure the safe and effective repair of hazardous electrical equipment. Schneider Electric issued a press release to remind companies of the precautions they should take to ensure employee safety and avoid costly damage to physical equipment and the financial losses of a prolonged shutdown.
If electrical equipment has been submerged or come into contact with water, it must be replaced, according to Schneider Electric. There are exceptions to this rule for larger equipment, which might be able to be reconditioned, including switchboard enclosures and certain bus structures; switchgear; low-voltage power circuit breakers; medium-voltage circuit breakers; low-voltage bolted-pressure switches; medium-voltage switches; motor control center (MCC) enclosures and bus structure; panelboard and load center enclosures; liquid-filled power transformers; cast-resin transformers; and busways with epoxy coated bars.
Attempting to dry out the equipment (in many cases) leaves portions of the current-carrying parts with damp or wet surfaces. These surfaces may be in contact with insulators or other materials that prevent them from being properly dried out and cleaned of debris. Residual debris or wet surfaces may result in a loss of dielectric spacing within the equipment, and could present a hazard upon re-energization.
Equipment that must be replaced in its entirety includes miniature and molded case circuit breakers; molded case switches; multi-metering equipment; safety switches (ac and dc); load centers or panelboard interiors; dry-type transformers; busways with mylar wrapped bars; solid-state components; programmable logic controllers; fuses; electromechanical relays, contactors, starters, pushbuttons, limit switches, and other input logic and output controls; solid-state motor starters; adjustable-speed drives; and MCC components.
If equipment was not submerged, Schneider still recommends having it inspected carefully to determine whether moisture has entered the enclosure. If any signs of moisture or damage exist, the equipment should be replaced or repaired.
Field-replaceable interior components are generally limited to a load center or panelboard type of product where the entire assembly can be removed and replaced as a unit. In this case, there is a possibility that enclosures can be reused if they have not been subjected to physical damage and if they have been properly cleaned of all debris and foreign materials.
In cleaning equipment, do not apply cleaning agents, particularly petroleum-based cleaners, to the current-carrying portions of electrical equipment to remove foreign debris, residues and other substances, Schneider says. Some cleaning and lubricating compounds can cause deterioration of the non-metallic insulating or structural portions of the equipment.
Do not use abrasives such as sandpaper or steel wool to clean current-carrying parts of the equipment. These materials may remove plating or other conductive surfaces from the parts, which could result in a hazard when the equipment is re-energized.
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- NEMA Standard AB 4-2003, Guidelines for Inspection and Preventive Maintenance of Molded Case Circuit Breakers Used in Commercial and Industrial Applications
- NEMA Standard BU 1.1-2000, General Instructions for Proper Handling, Installation, Operation and Maintenance of Busway Rated 600 V or Less
- NEMA Standard PB 1.1-2002, General Instructions for Proper Installation, Operation and Maintenance of Panelboards Rated 600 V or Less
- NEMA Standard PB 2.1-2002, General Instructions for Proper Handling, Installation, Operation and Maintenance of Deadfront Distribution Switchboards Rated 600 V or Less
- NEMA Standard ICS 1.1-2003, Industrial Control and Systems: Safety Guidelines for the Application, Installation and Maintenance of Solid-State Controls