Mechanical Consulting Group Inc.
2208 Magnolia Lane
Elgin, IL 60120
Ph: (630) 830-2083
Fax: (630) 830-0630


1. Find out if there are any other appliances that have been damaged, such as stereo equipment, televisions, ceiling fans, computers, cash registers, video recorders, alarm systems, clock radios, clocks that plug into the wall, garage door openers, control boards in furnaces and rooftop heating and cooling equipment, or other electronic equipment. Electronic equipment is far more susceptible to power surges or lightning damage than compressors or well pump motors. The possible exception would be if the insured has purchased a good surge protector for electronic equipment.

2. Find out if the neighbors have had damage due to lightning or a power surge. If lightning or a power surge came in on the power line, then all people off of the same utility transformer should have been affected.

3. Burned insulation on electric wiring is not necessarily an indication of a power surge due to lightning. Most of the time burned insulation on electric wiring is a sign of a loose connection. This is especially true if the wiring is burned at the connection. This is particularly true if the insulation is only burned in one location. Burned insulation on wiring is common at contactors (relays) for air conditioners. Burned insulation is also common at connections to fused or non-fused disconnects, and air conditioning compressor terminals. This is due to the large current draw and the loose connection which causes intense heat to be generated. The insulation is generally burned at the point of the connection and for a distance of up to two inches from the connection.

4. Many times an air conditioning compressor will pull a large amount of current due to mechanical problems which will cause the circuit breaker to trip or the fuses to blow. If the compressor cannot turn it will pull locked rotor amperes. The locked rotor amperes (LRA) is generally written on the unit and compressor name plate. If the compressor does not have oil, the bearings will seize and the compressor cannot turn. The locked rotor amperes of a compressor are typically three to five times the amount of running amperes. In other words if a compressor pulls 20 amperes while running it can pull as much as 60 to 100 amperes if the bearings are frozen and the compressor cannot turn. This can burn the contacts on a contactor and if there is the slightest loose connection it will burn the insulation at the point of connection.

5. There are companies that monitor lightning strikes. Price Hollingsworth and LWG are two companies that monitor lightning strikes. I have had varying reports on the success of these companies in tracking lightning strikes. Check with your employer to see if they have a company that they prefer you use.

6. A power surge due to lightning will generally cause the insulation to be burned in a number of areas. A power surge will generally cause a small arc from the wiring that runs against the metal cabinet to the case. Generally the arcs will be where the insulation was the weakest such as at a wiring bend or near a sharp edge of the cabinet. The amount of burned insulation on the wire depends upon the size of the power surge on the electric line. The size of the power surge is typically dependent upon how far away the lightning hit the power line and how much power the lightning strike had when it hit the power line. If there are lightning strikes on the power line it will generally trip the utility company circuit breakers and the utility company is aware of the lightning strike on their line.

The Engineering Committee for the Electrical Apparatus Service Association, Inc. has prepared a brochure on typical causes of winding failures in three-phase stators (motor windings) for three phase motors. Most of the members consist of companies that rebuild electric motors. The brochure lists 12 different failures (with large color photographs) of three phase motor windings. One of the failures is winding damage by voltage surge. This guide is used in investigation of all lightning claims for three phase motors.

If the insured is interested, the procedure of the investigation is explained in detail before the investigation is started. A copy of the investigation procedure is provided to the insured which explains what indicates lightning damage and what does not. The insured is welcome to watch the investigation and ask questions if necessary. The investigation will be done without bias.





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