How long does an electrical outlet last before it needs to be replaced?
The electrical outlet has become an essential part of modern life. Whether renting, owning, or at work, many people interact with electrical outlets dozens of times a day. Through repetitive use, electrical outlets are subject to a high amount of wear and tear. Inserting prongs from electrical cords in and pulling them out of outlets over and over causes parts inside the outlet to wear.
Electrical outlets do wear out depending on the frequency of usage and will need to eventually be replaced. But why do they wear out? Let’s explore that question.
How Electrical Outlets Work
Alternating current (AC) is the type of electricity that powers homes. Without getting too in-depth, direct current, or DC (like a car has), is better suited for short distances. Once the distance that the electricity needs to travel becomes great, DC voltage loses it’s “umph” and does not provide adequate electricity at the destination. Alternating current was developed for that specific purpose- to travel long distances without a significant loss in the ability to power homes (and do so cheaply).
Think of a circle with a starting point at the top. To make a complete circle, the start and end need to touch. The same is true for AC electricity. For AC electricity to work, it needs a complete circuit. Power is sent out on the hot wire, travels through the piece of equipment, and flows on the neutral wire back to the source*. It can be thought of as a continuous loop.
*For the sake of the explanation being suited for DIY home enthusiasts, I am leaving out AC voltage that has 2 or 3 hot legs and focusing on 110-120v single-leg voltage with a hot, neutral, and ground.
Who Created the Electrical Outlet
Since I geek out over knowing as much as I can about random facts, I can’t possibly leave out this fun fact about the electrical outlet. If you aren’t interested in some electrical outlet history, skip ahead to the Composition of an Electrical Outlet section.
Harvey Hubbel II was a brilliant entrepreneur and inventor who specialized in the invention of electrical items. Out of his 45 electrical-related United States Patents, his two most notable were the separable attachment plug and the pull-cord light switch.
Hubbel’s separable attachment plug (SEP) was the first version of the modern United States electrical outlet. Since the SEP was created in 1904 and the National Electrical Manufacturers Association (NEMA) was created in 1926, the SEP did not fall under NEMA standards or receive a NEMA code.
Hubbel’s design sparked massive growth in electrical receptacles and also in electrical safety. Since the SEP no longer required items to be hardwired to the electrical source, the SEP provided a safer alternative for people to attach anything using electricity. His electrical outlet design still saves lives to this day. Another additional thing of note about Hubbel is that his design and name are so ingrained in the electrical community that Hubbel is still one of the most common names in the electrical industry.
Composition of an Electrical Outlet
Electrical outlets are not complex. Their purpose is to allow an easy, quick way to connect a piece of equipment to a power source. Whether the outlet is for residential (your home) or commercial (buildings), the basics of the electrical outlet are the same.
The image above shows a cutaway of a basic self-grounded outlet*. On the left is the back-view of the outlet which shows the terminal contacts that an electrical plug’s prongs would slide into. The contacts are friction-fit, meaning each time the electrical plug is inserted into the outlet, it pushes the contacts apart. This action in addition to heat cycles from electrical current flow weakens the contacts over time.
On the right is the back view of an outlet with a three-prong plug inserted. When comparing the hot and neutral contacts of the left to the right, it can be seen that the plug prongs spread out the outlet terminal contacts. When the plug is removed, they return to their beginning width.
When inserting and removing plugs hundreds or thousands of time, the tabs become weaker and not able to completely return to their beginning width. Also, each time a plug is inserted, a very tiny amount of copper is worn off of the outlet’s contact. Lastly, heat from the flow of electricity adds to the weakening of the contacts.
While the effects mentioned above are very small, but they add up over time and result in the plug feeling loose when inserted into an outlet.
*The ground terminal for the ground wire on this particular outlet is permanently attached to the metal backplate, which is why it isn’t seen in the picture. The backplate clips in with the ground strap in the center of the outlet, providing grounding protection.
Description of Above Outlets
- Hot Side- Most modern outlets have one side on the back of the outlet labeled “Hot” to help identify the side of the outlet where the hot side wiring should be connected. Most outlets also have copper-colored wire connection screws, giving a visual indicator of the hot side of the outlet.
- Neutral Side- Most modern outlets have the side opposite the hot side on the back of the outlet labeled “Neutral” to help identify the side of the outlet where the neutral side wiring should be connected. Most outlets also have silver-colored wire connection screws, giving a visual indicator of the neutral side of the outlet.
- Contacts- Copper tabs spaced apart to allow a press-fit when a plug is inserted into the contact.
- Ground wire connection – provides a place to securely fasten the ground wire to the outlet. The wire is generally wrapped in a “C” pattern and clamped down with the screw.
- Screw-down wire terminals – wire is generally wrapped in a “C” pattern around the screw and clamped down with the screw.
- Back Wire Terminals- Not shown in the picture, but is common to most 15 and 20-amp home outlets. It provides a quick way to attach the wire to the outlet and comes in two types for 125v-rated home outlets, as explained later in this article.
Go onto the next page to see how to tell the hot and neutral side of an electrical outlet easily without having to remove it from the wall.
How to Tell Hot and Neutral Side of Electrical Outlet Easily
Outlets in the home can have the hot, neutral, and ground terminals easily identified from looking at the front of the outlet. The smaller blade terminal is hot, the larger is neutral, and the round (or tunnel-shaped) middle terminal is the ground. I know, some people are thinking that’s way too simple. I agree.
Description of Outlet Front
- Hot terminal – The National Electrical Manufacturers Association’s (NEMA) standard for 125v outlets and grounded plugs is the hot terminal must have a smaller prong size than the neutral prong.
- Neutral terminal- NEMA’s standard for 125v outlets and grounded plugs is the neutral terminal must have a larger prong size than the hot prong.
- Ground terminal- NEMA’s standard is a ground terminal will always accept a round or u-shaped prong which is ⅛” longer than the hot or neutral prongs. This allows for the ground prong on a plug to make contact before the other prongs, and to keep contact after the other prongs have been disconnected.
Little Known Fact: NEMA’s standards for grounding of outlets calls for the ground terminal on the outlet to be higher than the hot or neutral prongs, so if an object falls and makes contact with a plug while inserted into an outlet, it makes contact with the ground first. Then no matter which way the object continues falling and makes contact with the other prongs, it will safely short to ground.
Having the ground on the top of the outlet is not common in the home for aesthetic reasons, but is a safer configuration for outlets. A good example of where properly installed outlets can be seen are in hospitals.
Continue to the next page to learn how to properly wire outlets.
How to Properly Wire Terminals
To know the proper method of back wiring an outlet, you must know what type of back wire terminals the outlet has.
Two Types of Wire Terminals
There are two types of back wire terminals: Quickwire, and screw & clamp wire terminals. The back of the outlet will be labeled with the word “Quickwire” if the connection is Quickwire.
Which Type is Better?
Quickwire terminals aka “back wire” or “back stab” clamp the wire with only tension from a copper tab built into the contacts of the outlet. These tabs are not adjustable and have a high likelihood of getting loose over time if the following occurs: the wire is removed and reinserted, the outlet is not securely fastened to the wall, or the tab is subjected to excessive heat.
When the outlet is not secured to the wall properly and a plug is inserted and removed, it causes the potential for the wire to shift in the Quickwire connection, weakening the connection over time. A weak connection can cause excessive heat and/or arcing at the connection point.
Screw & clamp terminals
Screw & clamp terminals have an extra plate inside the outlet that is attached to the side screw terminal. When the wire is inserted into the back of the outlet and the side screw is tightened, it pinches the wire between two plates.
The screw & clamp terminal is a better alternative to the Quickwire terminal because the clamping force of the screw & clamp terminal will no fail from heat or outlet movement. Additionally, the screw & clamp terminal can be periodically checked for tightness and adjusted if necessary.
Important Tip for Both Terminal Types: Use the outlet’s built-in wire strip gauge to know if you’ve stripped the wire far enough to make a proper connection when back wiring an outlet. The gauge is always located on the back of the outlet, and looks like a rectangular box with some variation of the phrase “strip gage” or “strip gauge”.
Now that you’ve identified the correct type of terminal, ensured the wire is stripped properly, and know which side of the outlet the wire will be inserted into, insert the wire into the hole in the back of the outlet. Do the same for the other wire.
If the connection is Quickwire, all that needs to be done after pushing the wire in is to hold the outlet and pull the wire. This checks that the wire has a good connection and will not pull out of the outlet.
If the connection is screw & clamp, insert the wire and tighten the side terminal until it is tight. Then hold the outlet and pull the wire. This checks that the wire has a good connection and will not pull out of the outlet.
Now that electrical outlets are de-mystified and you have an in-depth knowledge of them, understanding when they are worn and need to be replaced will be much easier. Don’t forget, the single most important thing to do before repairing any outlet is to ensure the breaker is turned off and to double-check with an electrical meter that there is no power at the outlet.