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Dryer Outlet - 3 prong or 4 Prong?

Electrical Repair and Service Greenville SC

Dryer Outlet - 3 prong or 4 Prong?


So you moved into a new home, and your dryer plug does not fit the receptacle. Either your dryer cord has too many or too few prongs to fit. This issue is common and doesn't mean your home has Bad Wiring, and it certainly doesn't mean you need to buy a new dryer. Homes built before the mid 90’s only required 3 prong receptacles, but in 1996 the National Electrical Code (NEC) mandated all new home wiring use a neutral for Dryer and Range electrical circuits. The change like most code changes was made to increase safety by limiting the potential for electrical shock, and this why your new home has a 4 prong dryer outlet and your dryer cord won’t fit.


Fact: The first Electric Dryer sold to the public was in 1938


Why was a change needed?


The potential for electrical shock was starting to become more and more of an issue with the rise of digital displays and components utilizing 120v for their operation even though the dryer circuit was 240v without a neutral. This condition becomes dangerous because the voltage is cycling back and forth on a ground wire instead of the required neutral wire. Since the metal frame of the dryer is bonded to the incoming ground wire, there was a potential to be shocked by stray voltage when touching the dryer. People are much more at risk if they are barefoot while using the dryer. What is the difference between 120v & 240v?


Fact: The term “220 volt circuit” is not accurate in the United States, we use 240 volts as a standard although most appliances still run off 240v or 220v. A dryer using 5000 watts when supplied with 240v draws 20.83 amps while a dryer using the same 5000 watts when supplied with 220v draws 22.73 amps. The 240v system is much more efficient.


What was the solution?


The obvious solution was to add a neutral wire so the 120 volt components could operate safely without being used as a neutral path. Modern homes are wired using 10-3 NM Cable (Romex) and have four prong dryer receptacles installed. This wiring method safety carries all voltage back to the main electrical panel where the ground and neutral are bonded together. Any faults that occur use the grounding path to The Ground Rods or Grounding System and voltage travels into the Earth instead of energizing the metal frame of the dryer.  


Fact: Your dryer circuit should be supplied from a 2 pole 30amp Breaker. If it is more than 30 amps, the Wrong Breaker was installed. If your panel doesn't have breakers and still uses a cartridge and screw-in fuse it is time to think about a Panel Upgrade. Call an Electrical Contractor in Greenville for an evaluation.


What can you do?


Adding a 4 Prong Dryer Cord is the recommended course of action. With the average cost of a new cord being less than $25 and the installation involving the removal of a cover plate, 3 termination screws, and 1 ground connection this qualifies as a DIY project with many YouTube Videos offering advice. Although this is a moderate DIY project if you a are the least bit uncomfortable or unsure, please consider Hiring an Electrician in Greenville for assistance. Always turn off power and verify the power is off before working on any electrical system.


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