Slot Outlet
Standard electrical outlet in American homes. Each of the two outlets has a long (neutral) slot, a shorter (hot) slot and a half-round grounding hole. Standard electrical outlet in American homes. Each of the two outlets has a long (neutral) slot, a shorter (hot) slot and a half-round grounding hole.
Should the ground slot of a receptacle outlet be on the top or bottom?
Wednesday, February 5, 2020
The National Electrical Code (NEC) does not specify which way the ground slot should be oriented, and there is a somewhat logical explanation for putting it on top. If a piece of metal drops down onto a slightly-loose cord plugged into a ground-slot-up receptacle, the metal will only contact the ground slot. But it will cause a short, with possible arcing and sparks, when the hot and neutral are on top. Hospitals install receptacles ground-slot-up, likely to avoid any arcing in a room with oxygen in use.
Conversely, the argument against an upside down receptacle is that if the the cord is tugged out and downward (the usual way it happens), the ground can become disconnected with the cord still “live,” resulting in an ungrounded appliance that is still working. A receptacle with the ground slot on the bottom prevents this possibility.
Although the receptacle outlets in homes are usually installed with the ground slot on the bottom, some electricians put receptacles that are controlled by a wall switch with the ground slot up as a way to indicate which receptacle in a room is switched.
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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?
T Slot 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 can I figure out what a mystery wall switch does?
• 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?
Slot Outlet In Nigeria
• 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.
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Need to troubleshoot a dead outlet? Purchasing a multimeter, the go-to tool for diagnosing electrical problems, could allow you to investigate and address outlet issues. Not sure how to test an outlet? Read on, and the experts at Mr. Electric® will help you learn how to use a multimeter to test an outlet.
What Can a Multimeter Tell You?
A multimeter can help you determine:
- If power is actually reaching an outlet
- If the outlet is properly grounded
- Whether wiring within the outlet is reversed
How to Test an Outlet with a Multimeter in 8 Simple Steps
- Learn the essentials of outlet testing safety.
Because you will be performing these tests on a live outlet, ensure safety by holding both meter probes in the same hand. This will prevent shock from passing through your body. Never allow the metal portion of the probes to brush each other or touch, as this can create a dangerous short circuit. - Get to know outlet geography.
Modern outlets have three slots: one for hot, one for neutral, and one for ground. The rounded half circle is the ground, the longer slot (left) is the neutral and the shorter slot (right) is hot. Remember that any of the three wires can carry current, so treat each one with caution. - Adjust your multimeter.
Set your meter to measure voltage. Select the alternating current (AC) function on the multimeter, which is often depicted with a wavy line. The DC function will have a solid and a dashed line. - Connect the leads.
Push the short, thick connector (called a ‘banana plug’) of the BLACK lead into the connector labeled ‘COM’ (it may have a minus “-” sign beside it). Then, plug in the RED connector labeled with a “+” or horseshoe symbol (the Greek letter Omega). - Measure the voltage to determine if the outlet has power.
Using one hand, insert a probe into each vertical slot on the outlet. Red goes in the smaller slot, black into the larger one. A properly functioning outlet will give a reading of 110-120 volts. If there is no reading, either something is wrong with the wiring in the outlet or the circuit breaker is tripped. - Determine if the outlet is properly grounded.
Keep the red lead in the small slot and move the black lead and place it in the ground (Uu-shaped) outlet slot. The reading should remain the same. If it doesn’t, the outlet is improperly grounded. - Check if the wiring is reversed.
Place the red lead into the large slot and the black lead into small slot. If you get a reading, the wiring is reversed. This won’t affect simple equipment like lamps but can cause issues for more sophisticated appliances and electronics. - Determine problems with a particular appliance.
Learn “How to Make Electrical Tests” with the help of Mr. Appliance, a fellow Neighborly® home services company.
Count On Mr. Electric for Safe, Prompt Electrical Service
Need to resolve your outlet issue? Avoid a hair-raising electrical experience. Your local Mr. Electric will be happy to help with any electrical projects you’ve been putting off. Schedule an appointment online or call us at (844) 866-1367. Contact Mr. Electric today.
This blog is made available by Mr. Electric for educational purposes only to give the reader general information and a general understanding on the specific subject above. The blog should not be used as a substitute for a licensed electrical professional in your state or region. Check with city and state laws before performing any household project.