When did polarized plugs come out?
Although polarized outlets and plugs were introduced in the 1880s, they were not popular at first and did not become standard until the mid-20th century. What is the point of a polarized plug? Most appliances would work if they were plugged in "upside down."
Why are electrical plugs polarized?
Polarized outlets and plugs are used primarily as a safety feature to help prevent the danger of electrical shock. On such a device, if the plug were non-polarized, electrical components would likely retain an electrical charge even if switched off, producing a severe risk of electrical shock.
Which leg is neutral in a polarized plug?
With a NEMA 1-15 polarized plug, there is no ground terminal, only line and neutral. The neutral blade is wider than the line (hot) blade is. In the socket, the slot is wider. “If all the wiring is done to the national code, the neutral polarity is connected in a known condition.
What is the purpose of polarized electrical plugs?
Why Do Some Electrical Plugs Have Polarity?
- Identification. Polarized plugs are designed to be used in only one orientation, meaning that each blade of the plug is supposed to be inserted into a specific hole in the ...
- Purpose. Polarized outlets and plugs are used primarily as a safety feature to help prevent the danger of electrical shock.
- Non-Polarized. ...
- Warning. ...
Are polarized plugs required?
Non-polarized outlets were common in older homes, changing any non-polarized outlets you may have in your home will keep your house current on safety codes. Every outlet should be replaced with a polarized outlet in an up-to-date home sale for safety.
When did grounded plugs become standard?
In 1971, the US National Electrical Code (NEC) required grounded receptacles in all locations of the home (effective January 1, 1974).
Why are some plugs not polarized?
Plugs with the two of the same-sized prongs are considered non-polarized because there is no clear distinction as to which prong is for the “hot” side and the “neutral” side.
Can I replace a polarized plug with a non-polarized plug?
replacing a functioning non-polarized plug with a polarized plug will not make it safer. However, the opposite (replacing a polarized plug with a non-polarized plug) could make a device unsafe to operate.
What happens if a 3 prong outlet is not grounded?
An ungrounded three-prong outlet increases the potential for shocks or electrocution, and prevents surge protectors from doing their job, which may allow for damage to electronic components.
Are ungrounded outlets legal?
If an ungrounded outlet has GFCI protection, it is legal to put a grounded receptacle there. However, the receptacle must have the "GFCI Protected" label, and it must also have a "No Equipment Ground" label. So that settles it. It's legal if those labels (and GFCI protection) are present.
How do you wire a non polarized plug?
If the plug is polarized, put the hook of the neutral wire over the silver screw in the plug, with the hook going clockwise around the screw. If the plug is not polarized, hook the wire around either prong. Tighten the screw, making sure to sandwich as much copper as possible under the screw when completely tightened.
Are 2 prong outlets legal?
Are Two Prong Outlets Legal? According to the National Electric Code, two-prong outlets are allowed in homes as long as they are properly working. If you choose to replace your two prong outlet, you do not have to upgrade to a newer model.
What is the point of a polarized plug?
But humans using the appliance do care: polarization makes sure that it is the “hot” wire that goes through the switch of the appliance, so that as long as the switch is off, no electricity is even entering the working parts of the appliance.
Why are polarized plugs safer?
Most appliances would work if they were plugged in "upside down." But it provides a measure of safety for the appliance and house wiring to be aligned in terms of polarity. This is the reason why most appliance plugs are polarized—so they can only be plugged in neutral-to-neutral, hot-to-hot.
Are extension cords polarized?
A polarized plug is found at the end of an electrical cord on an appliance and on some heavy-duty indoor and outdoor extension cords. Electrical appliances have specific certification guidelines that must be followed to comply with safety regulations in the United States and Canada.
Why do electric cords have 2 holes?
These bumps fit into the holes so that the outlet can grip the plug's prongs more firmly. This detenting prevents the plug from slipping out of the socket due to the weight of the plug and cord. It also improves the contact between the plug and the outlet.
When did polarized outlets become standard?
Although polarized outlets and plugs were introduced in the 1880s, they were not popular at first and did not become standard until the mid-20th century.
Why are electrical outlets polarized?
Why are electrical outlets and plugs polarized? Wednesday, July 11, 2018. Polarized electrical cord plugs are designed so that they can only fit into a socket/outlet one way. One of the two vertical prongs is slightly taller than the other, with a corresponding tall and short slot in the outlet, which makes it impossible to insert ...
How many times does a polarized receptacle change direction?
Since household electricity at wall receptacles is a 60-hertz alternating current, meaning that the electron flow changes direction back-and-forth 60 times per second, it might seem like polarization is a pointless waste of time.
When was the first plug invented?
The first US power plug and socket dated 1904. Several early American electrical plug and socket arrangements were invented by Harvey Hubbell. On 26 February 1903 he filed two patent applications featuring 2-pin plugs and adaptors for using his plugs with existing designs of lamp sockets and wall receptacles.
When did plugs come out with parallel flat pins?
Plugs per se with parallel flat pins, such as the "Fort Wayne" design were in common use by 1886, and flush receptacles, such as the "Bryant Electrical Company" design, by 1902. Hubbell had introduced its own parallel flat pin configuration in 1912.
What is the IEC 60884-1?
The international standard IEC 60884-1 defines the general requirements for plugs and sockets intended for household and similar purposes, IEC 60884-1 does not define specific plug and socket types , which are the subject of national standards in each country.
What is a patent for a plug?
In one patent, U.S. Patent 774,250 a plug was used with a socket which screwed into a lampholder (like the early lampholder plugs). In the other patent U.S. Patent 776,326 the same type of plug was used with various three-way adaptors that could be connected to lampholders or "a receptacle of any ordinary type".
How many round pins did Hubbell have?
Hubbell's first plug design had two round pins which differed from those already in use in Europe in that the tips of the pins had annular detents similar to those of present-day jack plugs to positively retain a plug in its socket.
When was the first electrical socket invented?
An early American electrical plug and socket was invented by Harvey Hubbell and patented in 1904. Hubbell's first design was a socket which screwed into a lampholder (like the early lampholder plugs), but with a separable plug with pins ( U.S. Patent 774,250) or blades (US patent 774251). The 1906 Hubbell catalog shows the blade plug with a flush mounting socket for use in wall or floor. Other manufacturers adopted the Hubbell pattern, and by 1915 they were widespread.
What type of plugs did Hubbell use in 1906?
Hubbell's catalogue of 1906 includes various three-way adaptors similar to those shown in the US 776,326 patent, but modified for use with the coplanar flat pin plugs. The Chapman receptacle must have been in general use at the time, as it was the only type of non-lampholder receptacle for which adaptors were supplied.
Why are most appliance plugs polarized?
But it provides a measure of safety for the appliance and house wiring to be aligned in terms of polarity. This is the reason why most appliance plugs are polarized—so they can only be plugged in neutral-to-neutral, hot-to-hot.
What is a grounded plug?
When there are three prongs, these are known as "grounded plugs," and they are designed ...
What does it mean when an outlet is unpolarized?
This too is sometimes seen in older homes. When you find an outlet that has vertical slots exactly the same width, it means you are probably looking at wiring that is quite old. These unpolarized outlets can be very inconvenient since polarized plugs will not even fit into them.
What is the plug on the end of an electrical cord called?
At the end of any appliance electrical cord, there is a plug with two or three prongs (blades) designed to fit into standard wall outlet receptacles. When there are three prongs, these are known as "grounded plugs," and they are designed to fit into wall outlets so the round bottom prong fits into the ground slot on the outlet ...
How many prongs does a plug have?
Many plugs have only two prongs. On two-prong plugs, there is no ground wire connection, as it's deemed unnecessary. In these plugs, one of the blades of the plugs connects to the neutral wires running through the appliance, while the other blade connects to the "hot" wires.
Can you use an unpolarized plug on an old lamp?
It is entirely likely that you have some appliances or other devices around your house in which the plugs have blades of equal width—nothing to distinguish neutral from hot. These are unpolarized plugs. Older lamps and other devices may well have unpolarized plugs, and some modern electronic devices, such as chargers on computers or cell phones, also have simple unpolarized plugs. It is generally not a problem to plug in an unpolarized plug to a polarized outlet in whatever way it will fit. But anytime you are replacing a plug on an older lamp or appliance, it's a good idea to install a new polarized plug.
Is it safe to plug a 3 prong plug in a backwards outlet?
This is not a safety hazard; however, a backward outlet can be dangerous. Devices with three-prong grounded plugs are automatically polarized since there is only one way to insert the plugs into a wall outlet. That is provided, of course, that both the wall outlet and the plug are wired correctly.
