Peter McCarthy Electric Co., Inc. - Specializing in Older Buildings in Chicago
Adventures in Old House Wiring....

Time to look at your electrical service.

Here in Hyde Park, Chicago, the July heat has descended. We hit 96 degrees last week and we should be in the 90s for much of the summer. This is a good time to take a look at your electric service. If you have an antiquated service like this one, a 100 Amp service that is past it's prime in any number of ways, it might be wise to consider upgrading to a 200 Amp service. Summer is the time when multiple room air conditioner circuits become overloaded, and larger 220 lines are taxed to the limit by central air conditioners. This service is quite out of date. The cables are undersized, frayed and have been subjected to years (generations?) of sunlight and the elements. There is no grounding on this meter socket, a clear electrical safety issue. The internal components and connections no doubt have extensive corrosion on them, leading to additional overheating. The current has to fight to overcome the resistance offered by the corrosion (electrical friction) and already overtaxed connections are put under further stress. Independent of the fuses, circuit breakers or other electrical protection within, this system is long past its prime. If this homeowner added a new central air conditioner without a service upgrade, he or she would be asking for trouble.

Moreover, if there was a lightning strike very close-by, (Contrary to layman's understanding, it does not have to be a direct strike on the building, it can just be close by) like the one that hit in one of our clients' yard at 53rd and University two years ago, most of the consumer electronics in the home would be destroyed. The massive magnetic field created by the lighting that hit a tree behind the house induced a secondary high voltage current on the Edison service wire running over the yard, through the old service cable like this one, through the meter socket, panel, all of the individual breakers and branch circuits and to ground in as many routes as it could locate. The grounded neutral conductors of the individual branch circuits all offered tempting targets. The result was an extremely high voltage to the flat screen TV, computers, microwave, stereo, printer, ect. I can't remember everything that was on his insurance claim. As I recall, the replacement cost of the appliances was nearly as much as the new service cost.  But at least he had insurance.

Long story short, the NFPA stipulates these rules for a very good reason. The National Electrical Code and the Chicago Electrical Code both require a main and a supplemental grounding system for a service. This one obviously has no supplemental ground, which would be present in the form of a driven 8' copper ground rod bonded through conduit and copper cable to the meter housing. More than likely, there is a very undersized and corroded grounding connection inside somewhere. Like many on the South Side of Chicago, this is service needs to be replaced, and any legitimate electrical contractor would tell you that. Next time you are out in the yard, it would be worth taking a look at yours!
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