How Does Water Get Into Electrical Panels?
As part of the requirements for a properly performed New Jersey home inspection the electrical panel box cover has to be removed (if it can be removed safely) so the interior of the panel can be viewed and inspected. The New Jersey home inspector is required to inspect the internal electrical connections, breakers, grounding, wire type, wire size, box condition, wire condition, main breaker, and panel condition. One of the problems or conditions that I often discover while performing home inspections is rust inside the electrical service panel. Finding corrosion and rust is actually quite common.
Most of the moisture that finds its way into the electrical service panel is from rain water.
A poor seal at the top of the outside electric meter and/or a frayed main electric service cable (service drop) are the main causes for the moisture problems in the panel boxes.
Water can travel down the interior of the coated electrical wire and then can enter the panel. The service wire will act like a sealed pipe bringing moisture into the panel box. If the electric meter is not tightly sealed at the top where the service cable enters. Wind driven rain can also infiltrate a frayed or damaged main service cable and travel down to the panel box. A frayed or damaged lower service entrance wire will also contribute too the cause of moisture issues in the panel.
During the NJ home inspection we will inspect for this type of water infiltration and electrical panel damage. Often the terminals and the circuit breakers will become rusted and corroded due to the moisture in the panel box. Many times the bottom of the metal service panel will be rusted. Sometimes water is found in the bottom of the electrical panel box. On at least one inspection water was dripping from the bottom of the panel box. I did not remove the panel cover because of the unsafe conditions and electrical shock hazard.
Other less common causes of corrosion and rust are from water infiltrating or seeping through the basement foundation walls at the location where the panel box is attached. This in itself is a hazard because of the potential damage that can be caused by water seepage through the walls. Panel boxes should not be attached to stone, cement or masonry walls directly. Also interior condensation caused by high moisture levels in the home can contribute to panel box corrosion. High humidity levels can be caused by basement water infiltration or through other water leakage in the house.
A licensed electrical contractor should be called in to fully evaluate and correct the condition. The electrical contractor will have to locate the source of moisture and make required repairs or replacements. Often the panel box and wiring is very damaged and corroded, thus replacement will be required. Sometimes the panel box can be salvaged, in any event the origin of the moisture must be determined and repaired in order to avoid causing more damage.