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 ATI Technical Services Group

Guide to Restoration of Electrical Power after Water Damage


Entering or inhabiting a building without the proper safeguards in place to the electrical system is extremely hazardous and not recommended.  If a building has been flooded from rising water or saturated from above and the electrical distribution system was wet, or if the power company, local electrical inspector or building code official has “red tagged” a facility or placed a notification stating “electrical power is off and/or unsafe” – you should never attempt to operate electrical equipment or to turn on the electrical power. Even if someone tells you power is off you must confirm for yourself that power has been isolated and locked out.


Restoring power to flooded homes and buildings without proper assessments, testing, mitigation measures and restoration/refurbishment is detrimental and should not be done by anyone who is not electrically competent.  Risk of shock and fire to the buildings’ inhabitants or business employees is the obvious issue.  Buildings that have been inundated with water pose an immediate deadly threat to anyone just by entering the space.  Standing water can potentially become a source of electrocution if any live power is present.  Attempts to energize the electrical circuits or power electronics or equipment can kill.  Restoration of electrical systems and electrical powered equipment requires a special set of skills that are only available from skilled electricians, trained restoration professionals, technical specialists and engineers.


The potential for explosion, short-circuiting and electrocution from electrical power distribution systems that have been wet, flooded or rained upon is very high.  Even secondary moisture known as “high condensing levels of humidity” (which is outside of OEM specification) has had negative impacts and ongoing adverse consequences.


Action items if a facility or home has been wet or flooded:

First and foremost- if the branch feeders, main feeders or main panel is wet the power must be shut off by the utility company.  Confirmation that the utility cut-outs are open and/or the meter has been pulled cannot be assumed.  The building meter, disconnects or other mechanical means of opening the circuit so that power lines are open or disconnected to assure primary power is safely isolated or de-energized.


After verifying that utility power is off, only electrically trained persons should clear the building by first turning off the main breaker and/or removing the main fuse. Three-phase systems with low, medium and high voltage main breakers should be removed and un-racked.  Following standard Lock-Out/Tag-Out procedures for the electrical equipment according to OSHA guidelines is a must.

Wet resort and office buildings


After secondary power is confirmed off and properly tagged out, qualified and trained persons should visually inspect the wiring and distribution system for subsequent damages.


Wet residential panel board (breaker box)


Immersed appliances in homes should be unplugged and evaluated, restored and tested or replaced.  Fixed and movable machinery should be isolated from all electrical sources, and then capped off to ensure that, until properly serviced, accidental energy that would cause fire or failure is avoided.  Properly evaluated and mitigated equipment can then be serviced.  Guidelines and standards exist for restoration and refurbishment of electrical equipment. Low-end less expensive equipment should probably be replaced.  High value assets and “one-off” equipment require consideration for restoration versus replacement; often needing only decontamination, motor refurbishment, control panel repair and peripheral devices replacement.  Re-commissioning of this equipment should only be done by qualified persons after following guidelines.


Initial mitigation steps to building and control wiring recovery include gross contamination removal, dewatering and drying.  Initial steps are removal of panel covers, breaker box covers, wiring trough covers allowing for exposure and drying of wiring as well as troughs, conduits, panel boxes and j- boxes.  Removal and capping off and replacement of damaged devices are common.  Often this work requires a building permit and/or electrical permit.  Adhering to the local jurisdiction’s protocols is a must to proceed with this work.  A pre-inspection or initial inspection with local code officials is always suggested after the initial drying and stabilization has been performed to explain the steps, protocol and results of mitigation prior to moving forward.  Code officials who understand the scope of work often ‘bless the project’.  When the code official is ignored it can result in “red tagging jobs,” thus “shutting the site down”.  In some jurisdictions severe electrical damage may result in condemning the entire electrical system or, worse yet, condemnation of the entire structure.  Though electrical equipment and wiring can be successfully restored with some replacement, skipping code consultations and inspections is the wrong way to kick off a project.  This improper action could prove very costly and delay the project schedule, as well as continue to interrupt normal business activities.


Electrical equipment refurbishment with OEM intervention requires replacement of certain damaged   electrical devices according to UL and NEMA guidelines.  Once enclosures and wiring have been decontaminated and dried wiring must be tested according to OEM or NETA acceptance testing standards.  Only after passing appropriate testing should the necessary devices and components be replaced.


Subsequent to best practices of restoration and testing must be adhered to; a final electrical inspection must be conducted by local, state or any jurisdiction having authority.  After approvals and inspections, the final inspection authority can grant authority to re-energize the facility back to utility power.


Flooded main gear and power distribution system in industrial plant


Other life threatening caveats to consider:


  • Equipment that has been wet can hold hidden pockets of water which can short circuit causing failure or even electrocuting personnel.
  • Dry and wet transformers can be hazardous if re-energized resulting in explosion or fire.
  • Elevator and escalator equipment areas – Exposed motors and controls contain high voltage equipment and power in these areas that can kill.  In addition, moving parts are often exposed that can grab and pull a person into the equipment.  Keep unauthorized persons from entering these areas.
  • Fire Pumps – which are often fed from another power source can remain energized even if building power is off.  If a room is inundated with water you can be killed by opening a metal door or stepping in the water.
  • Back up Batteries and UPS systems can continue to power equipment even though the main power is off.
  • Backup Generators and Back UPS battery systems – can continue to feed a building if the main power is off.  The energy can feed down line and cause electrical shock and fires just like main utility power.  If the electrical system or building is wet the generator needs to be turned off and isolated from providing power.
  • Back feeding a building with a generator yourself without proper primary power isolation and disconnection from the grid can prove fatal for you or others on the system. 
  • Proper sizing generator, regulator and temporary cabling are a must.  Never do this yourself.
  • Low voltage communication control wiring and CAT 5/6 cables may appear impervious to water, but the water will migrate causing failure.  These cables must be treated and tested or data loss and intermittent faults are inevitable and wiring will need replacement.
  • Certainly just turning on the power (also called smoke testing) without proper mitigation and assessment is never recommended when equipment is wet and should never be done.  This will fail or shorten the life of all components, wiring, motors and devices.  Powering wet equipment and wire will advance corrosive activity.  Energizing a wet electrical system will compromise the integrity of the system and wiring and potentially damage components that could have been restored.

·         Untreated electrical systems are even more compromised by saltwater intrusion than by regular water, but both are a problem.  Fire suppression water is fairly dirty with hydrocarbons and oxides coupled with acid soot can be aggressive and cause corrosion. The flood waters (disregarding what other environmental waste may be in the rising floodwaters) is extremely corrosive and many times more aggressive than fresh water.  The effects on conductors made of copper, aluminum and base metals is a corrosive galvanic reaction. 

·         Untreated equipment and wiring results in future ongoing issues: nuisance trips, premature breaker replacement and untimely failure of electrical equipment.  Presently testing and restoration may be attributed to the event but, if ignored, will result in ongoing and unscheduled future maintenance issues paid for by the building owner, if not restored properly now.