LIGHTNING STRIKES –Ontario Electrical Safety Code – Info Sheet Rule 2-300 General Requirements for Maintenance and Operation
Rule 2-300 of the Ontario Electrical Safety Code requires that all operating electrical equipment be kept in safe and proper working condition. Defective equipment shall either be put in good order or permanently disconnected.
Electrical wiring and equipment is designed for specific operating voltages and when those voltages are exceeded during a lightning strike or voltage surge, the wiring and equipment may be damaged resulting in potential fire or shock hazards.
When electrical wiring and equipment is subjected to a lightning strike or voltage surge, all fixtures, switch, outlet and panel covers shall be removed and the wiring visually inspected for evidence of arcing or burning damage. Where evidence is found, then a further visual inspection of all wiring shall be done. This will likely result in removing wall and ceiling coverings to permit inspection of concealed wiring.
Where obvious visual damage is found throughout an electrical installation with appliances, receptacles, switches, fixtures, wiring or panels being damaged, then such installations shall be rewired completely.
All circuit breakers should be inspected for damage and ESA strongly recommends that any breakers that opened (tripped) be replaced.
All life safety devices must also be electrically tested and replaced where necessary. Examples are Ground Fault Circuit Interrupters (GFCI) including receptacle and circuit breaker types, Arc Fault Circuit Interrupters (AFCI), smoke and CO detectors, etc. All hard wired appliances such as furnaces, water heaters, air conditioning equipment, etc must be inspected and tested to ensure proper operation and repaired or replaced as necessary.
Measuring the insulation resistance and/or measuring the dielectric strength of concealed wiring are also tools that may be used to determine damage but are not fool proof in that a lightning strike or surge can damage cable and conductor insulation where it goes to ground when in contact with ductwork, pipes or metal structures but could have blown itself clear and may not show any damage when tested.
Rule 70-130 of the Ontario Electrical Safety Code provides guidance in doing these tests. These tests should be done by a qualified electrical contractor knowledgeable in the safe use of these test instruments and in the interpretation of the results. Where damage is limited only to electronic plug-in appliances and there is no visible evidence of damage to the electrical wiring system then no further action is normally required.
Note- An application for inspection of all electrical work including replacement of wiring, outlets, or hard-wired equipment, etc is required to be submitted to the Electrical Safety Authority.
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