Good morning! That's a tough situation for your customer. Flooding and electrical systems don't mix well. Here's a breakdown of my recommendations, focusing on safety and long-term reliability

General Principles:
Safety First

Prioritize safety above all else. Water and electricity are a deadly combination. Even if something seems dry, hidden corrosion and damage can create future hazards.

Corrosion

Saltwater (if present, even a trace) is particularly corrosive. Fresh water is less damaging, but still problematic.

Professional Judgment

This is a situation where your professional judgment is key. If you have any doubt about the safety or reliability of a component, replace it. The cost of replacement is far less than the potential cost of a fire or electrocution.

Documentation

Document everything you do, including photos and a detailed description of what was affected and how you addressed it. This will be helpful for insurance claims and future reference.

Coordination

Coordinate closely with the sheetrockers and the electrical inspector.

Warranty

Any electrical work performed should be warrantied. Consider the liability associated with warrantying equipment exposed to flood waters.

Specific Components



Circuit Breakers and Panel



Replace any circuit breakers that were submerged. Even if they appear to function, water can corrode the internal mechanisms and compromise their ability to trip properly in an overload or short circuit. Inspect the main electrical panel thoroughly. If the bottom of the panel was submerged, replace the entire panel. Corrosion can quickly spread, and the risk of future problems is too high. If the panel was not submerged

Carefully inspect all wiring connections inside the panel for corrosion. Clean and tighten connections if needed. Check the panel enclosure for rust. Consider applying a corrosion-inhibiting compound to the interior of the panel.

Receptacles, Switches, and Wiring Devices



Replace all receptacles and switches that were submerged. Water can damage the internal contacts and create a shock hazard. Test any receptacles and switches that were above the water line for proper grounding and operation. Wiring (EMT, MC Cable, THWN)



EMT Conduit



If the water line was above any horizontal runs of EMT

Assume that water entered the conduit.

Remove any junction boxes or fittings along the horizontal run to allow water to drain completely. Vacuuming

While vacuuming can help, it's difficult to ensure complete removal of water from EMT, especially if there are low spots or debris inside. Consider using a wet/dry vacuum. Be careful if water gets into the vacuum's motor housing.

Drying

After vacuuming, use fans and/or a dehumidifier to encourage further drying.

Inspection

After drying, inspect the wiring inside the conduit for signs of damage or corrosion. If in doubt, replace the wiring.

Consider

Replacing the EMT if the corrosion is severe.

MC Cable (Metal Clad Cable)



If the water line was above any significant length of MC Cable

Replace the affected section of MC cable. Water can wick inside the cable's armor, causing corrosion of the conductors. It is very difficult to get the water out.

Fans

Pointing fans at MC cable might help, but it's unlikely to dry it out completely, especially inside the armor.

THWN Wiring (Inside EMT or MC)



If the THWN wiring was submerged

While THWN is water-resistant, it's still best to inspect it carefully.

Visual Inspection

Look for signs of damage to the insulation (cracks, swelling, discoloration).

Megger Testing (Insulation Resistance Test)

This is the best way to determine if the insulation has been compromised. A low insulation resistance reading indicates that the wiring needs to be replaced.

Lighting Fixtures



Replace any lighting fixtures that were submerged. Water can damage the ballast, sockets, and wiring. Inspect lighting fixtures above the waterline for corrosion.

Answering Your Specific Questions



EMT/MC Cable - Replace or Dry? It depends on the severity of the flooding and your comfort level with the risk. In general, replacing MC cable is the safer option. For EMT, thorough drying and inspection are necessary, but replacement might be necessary if there's significant corrosion. Fans for Drying? Yes, fans can help speed up drying, but they are not a substitute for proper inspection and possible replacement. Vacuuming EMT? Yes, you can use a wet/dry vacuum to try to remove water from EMT. THWN Identification in Panel? Yes, THWN (or THWN-2, THHN/THWN, XHHW, etc.) will be printed on the cable's insulation. Look inside the panel where the wires enter and exit. You can also often see the printing on the wires in junction boxes.

Additional Considerations



GFCI Protection

Consider installing GFCI protection for all receptacles in areas that are prone to flooding.

Surge Protection

Recommend surge protection at the panel to protect sensitive electronic equipment.*

Future Flood Prevention

Discuss options for preventing future flooding with your customer. This might include improved drainage, flood barriers, or raising electrical equipment above the flood plain.

Important Note: This information is for guidance only. Always follow the National Electrical Code (NEC) and local codes, and consult with the electrical inspector to ensure compliance and safety.Good luck with the project! Flag for review