Hurricane season is over, and the inundation of floodwaters in many parts of the country has likely receded by now. However, evaluating electrical equipment that has been subjected to water and determining whether to recondition the equipment or replace it remains a serious issue. Electrical equipment that has been exposed to water can be extremely hazardous if the equipment is re-energized without proper reconditioning or replacement. Water from floods can be contaminated with chemicals, sewage, oil, saltwater from the ocean, and other materials that can damage the electrical equipment and can affect the integrity or operation. (See Jeff Griffin’s “Buyer Beware” and “Disaster After The Disaster?”)

Section 110.12(B) of the 2011 National Electrical Code (NEC) states that internal parts of electrical equipment, such as busbars, wiring terminals, conductors, insulators and other parts of the electrical equipment must not be damaged or contaminated by foreign materials, paints, plasters, cleaners, abrasives or corrosive residues that may adversely affect the operation of the equipment. This section was inserted to specifically allow the electrical inspector to reject any electrical installation or electrical equipment where there is damage or possible deterioration from corrosion and chemical action or reaction.
The National Electrical Manufacturers Association has issued a publication that provides information and advice on how to evaluate electrical equipment that has been exposed to water through flooding, firefighting activities, hurricanes or other water-related issues. “Guidelines for Handling Water--Damaged Electrical Equipment” is available to distributors, electrical contractors, inspectors and residents in water-damaged regions online at www.nema.org or can be downloaded at www.nema.org/stds/water-damaged.cfm.

The electrical equipment covered in this NEMA document includes electrical distribution equipment; motor circuits; power equipment; transformers; wire, cable and flexible cords; wiring devices; ground-fault circuit interrupters (GFCIs) and surge protective devices; luminaires and ballasts; motors; industrial controls; and cable trays. It also provides recommendations for electronic products such as signaling; protection systems, such as security and fire alarm systems; and communications systems. Each type of electrical equipment must be treated individually and differently based on the potential hazard or exposure, and working knowledge of the electrical system and equipment is a must. Where the electrical system is complex or intricate, consulting the equipment manufacturer is imperative so that properly trained personnel can assist in reconditioning it. Remember, the possibility of reconditioning electrical equipment varies with its function, degree of flooding, age of the equipment and length of time it was exposed to the water.

NEMA recommends the replacement of molded-case circuit breakers and low-voltage fuses (those operating at 600 volts or less) and any Mylar-wrapped busways. Busways that have powder-coated busbars may be reconditioned where the possible damage has not affected the overall coating on the busbars. Any low-voltage electronic trip power circuit breakers must be replaced since the internal trip solid-state components are very sensitive to corrosion, and the breaker may fail to operate properly. The same replacement requirement applies to any motor-control equipment that contains semiconductors or transistors, overload relays or electronically controlled solid-state contactors and starters. Any dry-type transformer, regardless of kilovolt-ampere rating, must be replaced since the water will have compromised the insulation integrity of the windings, and core corrosion has likely occurred. The liquids within liquid-filled transformers will most likely have been contaminated by chemicals, saltwater, or other similar materials that will have affected the windings, the core and the insulation.

Wire or cable listed for use only in dry locations, such as NM-B or AC cables, must be replaced since the metallic components enclosing or within the cable will have been subjected to corrosion. In addition, the paper wrap inside the cable will have been saturated with water, possibly affecting the deterioration of the conductor and accelerating insulation failure within the cable. Metal-clad cables or the metal jacket or armor on similar types of cables are subject to corrosion with serious ramifications to the effective bonding and grounding capacities of the armor or cable assembly. The corrosion of wire and cable terminations is a very serious concern since deterioration is usually most evident at those points, and overheating and short circuiting can occur at these locations.

Wiring devices, such as arc-fault circuit interrupter circuit breakers; GFCIs; surge-protective devices; and electronic components for fire alarm systems, security systems and other life safety systems, generally contain electronic components where the exposure to contaminants and water may adversely affect the reliability of these systems. These devices must be replaced, since the proper operation of this equipment is critical to safety and must not be compromised.


ODE is a staff engineering associate at Underwriters Laboratories Inc., based in Peoria, Ariz. He can be reached at 919.949.2576 and mark.c.ode@us.ul.com.