Background: Recently, I was asked to provide an electrical service inspection on a two story residence that had suffered a house fire started by an automobile that was in contact with the garage door. For a sense of scope, the fire melted the garage door and the plastic siding all the way to the roof before the fire was extinguished. The auto was totally destroyed.
Proximity: The electrical service meterbox and mast are located at the same corner as the garage door. One edge of the meterbox was directly exposed to the fire (4 ft) and the surface of the exposed edge was smoke blackened but not heat buckled. The meter glass (not directly exposed but close) was intact and working. The service drop crosses the heat plume coming from the fire at approximately 15 feet from ground level. The service wires show evidence of light frosting (reduced shine) and delamination of the outer edges of the insulation. No conductor showing in the ungrounded lines.
My recommendations were to:
1. Replace the service entrance conductor based on probable exceeding their insulation temperature limits of 75 deg C and evidence of minor delamination.
2. Inspect the interior of the meter box for wire insulation damage for those parts in contact with metal (especially on the exposed edge) and damage to the bus bar insulators.
3. Retorque all meter box wire lugs.
Problem: The insurance company representative said that no action was required. The local inspector was called yesterday to inspect the post fire service and told the owner that there was no problem with the equipment and to continue operation.
Question: I expected the response from the insurance company but was very surprised at the decision of the local inspector. Was my inspection over critical? Were my recommendations overly cautious? Is there any advice or other technical resource recommendations to guide an electrician in the inspection of electrical equipment that is still operational but suspected of heat damage?
Thanks in advance, John King
p.s. No pictures on hand now but I may get some and post tomorrow
Proximity: The electrical service meterbox and mast are located at the same corner as the garage door. One edge of the meterbox was directly exposed to the fire (4 ft) and the surface of the exposed edge was smoke blackened but not heat buckled. The meter glass (not directly exposed but close) was intact and working. The service drop crosses the heat plume coming from the fire at approximately 15 feet from ground level. The service wires show evidence of light frosting (reduced shine) and delamination of the outer edges of the insulation. No conductor showing in the ungrounded lines.
My recommendations were to:
1. Replace the service entrance conductor based on probable exceeding their insulation temperature limits of 75 deg C and evidence of minor delamination.
2. Inspect the interior of the meter box for wire insulation damage for those parts in contact with metal (especially on the exposed edge) and damage to the bus bar insulators.
3. Retorque all meter box wire lugs.
Problem: The insurance company representative said that no action was required. The local inspector was called yesterday to inspect the post fire service and told the owner that there was no problem with the equipment and to continue operation.
Question: I expected the response from the insurance company but was very surprised at the decision of the local inspector. Was my inspection over critical? Were my recommendations overly cautious? Is there any advice or other technical resource recommendations to guide an electrician in the inspection of electrical equipment that is still operational but suspected of heat damage?
Thanks in advance, John King
p.s. No pictures on hand now but I may get some and post tomorrow
