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:
• What is the difference between what trips a GFCI (ground fault) receptacle and a circuit breaker?
• What is the code requirement for GFCI protection for receptacles near a wet bar sink?
• What is the requirement for a service receptacle outlet for heating, air conditioning, and refrigeration (HACR) equipment?
• Why is an opening in the wall around the side of an electrical receptacle outlet a safety defect?
• When was GFCI-protection for kitchen dishwasher receptacle outlet first required?
• What is allowable voltage range at a wall receptacle outlet in a house?
• When should I replace electric receptacle outlets?
• Does an electric receptacle outlet in a storage shed require GFCI protection?
• What are "self-contained" electrical receptacle outlets and switches?
• What is the difference between an electrical receptacle, an outlet, and a plug?
• Does a washing machine receptacle outlet require GFCI protection?
• What is the building code requirement for receptacle outlets at stairs and stair landings?
• Can I remove a 240-volt range receptacle and hard-wire the range?
• What is a "backstab" receptacle outlet?
• Why are some electric receptacle outlets upside down (ground slot up) in a house?
• What is the height requirement for an electric receptacle outlet?
• Where are GFCI receptacle outlets required?
• When were GFCI receptacle outlets first required?
• Does a home inspector remove receptacle outlet cover plates?
• What is the minimum height for an exterior receptacle outlet?
• When was the current receptacle/outlet spacing of 12-feet first required?
• When was the three-slot (grounding) outlet/receptacle first required?
• Why does painting an electric receptacle (outlet) make it unsafe?
• Why are electrical outlets and plugs polarized?
• How many electrical receptacles (outlets) are required in a hallway?
• What problems does having too many electric receptacle outlets on a single circuit cause?
• Is a house required to have outdoor electric receptacle outlets?
• How I can tell if a receptacle outlet is tamper resistant?
• Why is there a GFCI breaker in the electric panel for the bathroom shower light and exhaust fan?
• What is a false ground, bootleg ground, or cheated ground receptacle?
• How can adding wood paneling or a wainscot create an electrical safety hazard?
• How far apart should kitchen counter receptacles be spaced?
• How far above a kitchen countertop do electrical outlets have to be?
• What is reversed polarity at an outlet/receptacle? Why is it dangerous?
• How high above the floor do electric outlets/receptacles in a garage have to be?
• How far apart should electric receptacles be spaced in a bathroom?
• Is an ungrounded electric receptacle outlet dangerous?
• My bathroom electric receptacle/outlet is dead and there are no tripped breakers in the electric panel. What's wrong?
• Is there an adapter that can be placed on a two-slot receptacle to make it safe?
• How do the new tamper-resistant electric outlets work?
• Why is there no bathroom electric receptacle in this old house?
• How can I tell if the electric receptacle outlets are grounded?
• How far apart should the electrical receptacles be placed?
• What are the most common problems/defects found with electric receptacle outlets during a home inspection?
Visit our ELECTRICAL page for other related blog posts on this subject, or go to the INDEX for a complete listing of all our articles.