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What problems does having too many electric receptacle outlets on a single circuit cause?
Thursday, July 12, 2018
Older houses are especially prone to having too many outlets on one circuit, usually because of adding more outlets and lights for a home addition or conversion of a garage to living space without running new circuits to the panel. Overloading branch circuits can cause problems in four ways:
1) If too many appliances are turned on at the same time, the circuits may be so heavily loaded that the voltage drops significantly. A voltage drop of up to 10% below the nominal 120 volts of the circuit is acceptable but, when it drops under that, you get a situation similar to an electric utility brownout. Low voltage makes it difficult for electric motors to start up and many other appliances will simply not work properly.
2) Too many outlets can also cause “nuisance tripping” of a circuit breaker, when a breaker trips repeatedly due to excessive current flow from too many things plugged into the circuit and on, even though there is nothing wrong with the wiring.
3) The wire itself has a certain amount of electrical resistance for each foot of length. Although small, it adds up incrementally, and an additional 50 feet of cable run adds 100 feet to the circuit because of the round trip of the current, which can result in an unacceptable voltage drop—and poor performance of some appliances.
4) Every wire connection along the way at each outlet also adds resistance, with the same consequence.
There is no limitation for the number of general purpose outlets on a circuit, and an excessive number of receptacles does not automatically create a safety problem. However, a professional electrician takes into consideration the length of the cable runs and allows a reasonable number of receptacles based on anticipated usage in laying out the circuits around the home.
While too many outlets on one circuit can be problematic, checking for it requires troubleshooting that is beyond the scope of a home inspection.
Also, see our blog posts When should I replace electric receptacle outlets? and How can I tell if the electric receptacle outlets are grounded?
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To learn more about electrical wiring, devices, and receptacles, see these other blog posts:
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