3-way lamp

Last updated

A 3-way lamp, also known as a tri-light, is a lamp that uses a 3-way light bulb to produce three levels of light in a low-medium-high configuration. A 3-way lamp requires a 3-way bulb and socket, and a 3-way switch.

Contents

In 3-way incandescent light bulbs, each of the filaments operates at full voltage. So unlike incandescent bulbs controlled by a dimmer, the color of the light does not change between the three steps of light available.[ citation needed ] Lamp bulbs with dual carbon filaments were built as early as 1902 to allow adjustable lighting levels. [1]

Certain compact fluorescent lamp bulbs are designed to replace 3-way incandescent bulbs, [2] and have an extra contact and circuitry to bring about similar light level. In recent years, LED 3-way bulbs have become available as well. [3]

3-way bulbs

The contacts of a 3-way bulb 3Way Bulb Contacts.jpg
The contacts of a 3-way bulb
Circuit diagram of a 3-way bulb 3Way bulb diagram.svg
Circuit diagram of a 3-way bulb

A 3-way incandescent bulb has two filaments designed to produce different amounts of light. The two filaments can be activated separately or together, giving three different amounts of light. One common 3-way incandescent bulb is the 50/100/150 W. It has a low-power 50 W filament and a medium-power 100 W filament. When they are both energized at the same time, 150 W of power is delivered, and a high level of light is produced. Usually screw-base 3-way bulbs fit into regular Type A sockets (E26D after ISO 60061-1:2014). Larger 3-way bulbs (up to 300 W) have a larger "mogul" base (E39D). These 3-way bulbs can also come in spiral-shaped compact fluorescent lamps. [2]

3-way sockets

3Way Socket Contacts.jpg
Inside a 3-way socket
Keyless 2Way Socket.jpg
The base of a keyless 3-way socket

A standard screw lamp socket has only two electrical contacts. In the center of the bottom of a standard socket is the hot contact (contact one in photo), which typically looks like a small metal tongue bent over. The threaded metal shell is itself the neutral contact (contact three in photo). When a standard bulb is screwed into a standard socket, a matching contact on the bottom of the bulb presses against the metal tongue in the center of the socket, creating the live connection. The metal threads of the bulb base touch the socket shell, which creates the neutral connection, and this is how the electrical circuit is completed.

A 3-way socket has three electrical contacts. In addition to the two contacts of the standard socket, a third contact is added. This contact is positioned off-center in the bottom of the socket (contact two in photo). This extra contact matches a ring-shaped contact on the bottom of a 3-way bulb, which creates the connection for the second filament inside the bulb. A problem of these devices is that the ring contact of the socket (contact two in photo) digs into the lead seal on the lamp bulb's contact ring and this connection tends to fail early (sometimes in months), leading to intermittent flashes, popping noises, and loss of power to the low wattage filament as the lead seal on the bulb's ring alternately melts and solidifies.

The center contact of the bulb typically connects to the medium-power filament, and the ring connects to the low-power filament. Thus, if a 3-way bulb is screwed into a standard light socket that has only a center contact, only the medium-power filament operates. In the case of the 50/100/150 W bulb, putting this bulb in a regular lamp socket will result in it behaving like a normal 100 W bulb.

A key switch 3-way socket has the switch incorporated in the lamp socket and requires no external wiring between switch and socket. This would be typical in a 3-way floor-standing floor lamp. A 3-way socket that is to be wired to a separate 3-way 2-circuit switch, is called a keyless 3-way socket. [4]

3-way, 2-circuit switches

Circuit diagram of a 3-way switch and socket 3WayCircuitAnimation.gif
Circuit diagram of a 3-way switch and socket

The switch used to control a 3-way lamp is usually a rotary switch or a pull-chain switch. Although it is referred to as a 3-way switch, it has four positions, off, lamp one (low), lamp two (medium), and lamps one and two (high). When properly connected to a 3-way socket containing a 3-way bulb, this switch will first power one filament, then the other filament, then both, then return to the off position. To do this, the switch must be capable of operating two different circuits. Internal to the switch there are two sets of switch contacts that are not connected electrically, but which are connected mechanically in such a way that they operate together as shown in this table.

Lamp functionSwitch oneSwitch two
OffOffOff
Low, lamp oneOnOff
Medium, lamp twoOffOn
High, lamps one and twoOnOn

See also

Related Research Articles

<span class="mw-page-title-main">Electric light</span> A device that produces light from electricity

An electric light, lamp, or light bulb is an electrical component that produces light. It is the most common form of artificial lighting. Lamps usually have a base made of ceramic, metal, glass, or plastic, which secures the lamp in the socket of a light fixture, which is often called a "lamp" as well. The electrical connection to the socket may be made with a screw-thread base, two metal pins, two metal caps or a bayonet cap.

<span class="mw-page-title-main">Incandescent light bulb</span> Electric light bulb with a resistively heated wire filament

An incandescent light bulb, incandescent lamp or incandescent light globe is an electric light with a wire filament heated until it glows. The filament is enclosed in a glass bulb with a vacuum or inert gas to protect the filament from oxidation. Current is supplied to the filament by terminals or wires embedded in the glass. A bulb socket provides mechanical support and electrical connections.

<span class="mw-page-title-main">Halogen lamp</span> Incandescent lamp variety

A halogen lamp is an incandescent lamp consisting of a tungsten filament sealed in a compact transparent envelope that is filled with a mixture of an inert gas and a small amount of a halogen, such as iodine or bromine. The combination of the halogen gas and the tungsten filament produces a halogen-cycle chemical reaction, which redeposits evaporated tungsten on the filament, increasing its life and maintaining the clarity of the envelope. This allows the filament to operate at a higher temperature than a standard incandescent lamp of similar power and operating life; this also produces light with higher luminous efficacy and color temperature. The small size of halogen lamps permits their use in compact optical systems for projectors and illumination. The small glass envelope may be enclosed in a much larger outer glass bulb, which has a lower temperature, protects the inner bulb from contamination, and makes the bulb mechanically more similar to a conventional lamp.

<span class="mw-page-title-main">Fluorescent lamp</span> Lamp using fluorescence to produce light

A fluorescent lamp, or fluorescent tube, is a low-pressure mercury-vapor gas-discharge lamp that uses fluorescence to produce visible light. An electric current in the gas excites mercury vapor, which produces short-wave ultraviolet light that then causes a phosphor coating on the inside of the lamp to glow. A fluorescent lamp converts electrical energy into useful light much more efficiently than an incandescent lamp. The typical luminous efficacy of fluorescent lighting systems is 50–100 lumens per watt, several times the efficacy of incandescent bulbs with comparable light output. For comparison, the luminous efficacy of an incandescent bulb may only be 16 lumens per watt.

<span class="mw-page-title-main">Flashlight</span> Portable hand-held electric light

A flashlight or torch is a portable hand-held electric lamp. Formerly, the light source typically was a miniature incandescent light bulb, but these have been displaced by light-emitting diodes (LEDs) since the mid-2000s. A typical flashlight consists of the light source mounted in a reflector, a transparent cover to protect the light source and reflector, a battery, and a switch, all enclosed in a case.

<span class="mw-page-title-main">Mercury-vapor lamp</span> Light source using an electric arc through mercury vapor

A mercury-vapor lamp is a gas-discharge lamp that uses an electric arc through vaporized mercury to produce light. The arc discharge is generally confined to a small fused quartz arc tube mounted within a larger soda lime or borosilicate glass bulb. The outer bulb may be clear or coated with a phosphor; in either case, the outer bulb provides thermal insulation, protection from the ultraviolet radiation the light produces, and a convenient mounting for the fused quartz arc tube.

<span class="mw-page-title-main">Compact fluorescent lamp</span> Fluorescent lamps with folded tubes, often with built-in ballast

A compact fluorescent lamp (CFL), also called compact fluorescent light, energy-saving light and compact fluorescent tube, is a fluorescent lamp designed to replace an incandescent light bulb; some types fit into light fixtures designed for incandescent bulbs. The lamps use a tube that is curved or folded to fit into the space of an incandescent bulb, and a compact electronic ballast in the base of the lamp.

<span class="mw-page-title-main">Hydrargyrum medium-arc iodide lamp</span>

Hydrargyrum medium-arc iodide (HMI) is the trademark name of Osram's brand of metal-halide gas discharge medium arc-length lamp, made specifically for film and entertainment applications. Hydrargyrum comes from the Greek name for the element mercury.

<span class="mw-page-title-main">Mogul lamp</span>

A mogul lamp or six way lamp is a floor lamp which has a large center light bulb surrounded by three smaller bulbs that may be candelabra-style or standard medium-base bulbs, each mounted base-down. This entire setting is typically covered, at least partially, by a large cylindrical fabric shade which is fitted over the reflector bowl, an upturned, white-colored glass, hemispherical diffuser surrounding the center bulb. The top of the lamp is usually designed to sit just above eye-level of an average adult person standing next to it, to avoid unpleasant glare from unshaded bulbs.

<span class="mw-page-title-main">Light fixture</span> Electrical device with an electric lamp

A light fixture, light fitting, or luminaire is an electrical device containing an electric lamp that provides illumination. All light fixtures have a fixture body and one or more lamps. The lamps may be in sockets for easy replacement—or, in the case of some LED fixtures, hard-wired in place.

<span class="mw-page-title-main">Stage lighting instrument</span> Device that emits light to illuminate performers

Stage lighting instruments are used in stage lighting to illuminate theatrical productions, concerts, and other performances taking place in live performance venues. They are also used to light television studios and sound stages.

<span class="mw-page-title-main">Bayonet mount</span> Fastening mechanism

A bayonet mount or bayonet connector is a fastening mechanism consisting of a cylindrical male side with one or more radial pins, and a female receptor with matching L-shaped slot(s) and with spring(s) to keep the two parts locked together. The slots are shaped like a capital letter L with serif ; the pin slides into the vertical arm of the L, rotates across the horizontal arm, then is pushed slightly upwards into the short vertical "serif" by the spring; the connector is no longer free to rotate unless pushed down against the spring until the pin is out of the "serif".

<span class="mw-page-title-main">Edison screw</span> Lightbulb socket standard (E5-E40)

Edison screw (ES) is a standard lightbulb socket for electric light bulbs. It was developed by Thomas Edison (1847–1931), patented in 1881, and was licensed in 1909 under General Electric's Mazda trademark. The bulbs have right-hand threaded metal bases (caps) which screw into matching threaded sockets. For bulbs powered by AC current, the thread is generally connected to neutral and the contact on the bottom tip of the base is connected to the "live" phase.

<span class="mw-page-title-main">Multifaceted reflector</span> Light bulb

A multifaceted reflector light bulb is a reflector housing format for halogen as well as some LED and fluorescent lamps. MR lamps were originally designed for use in slide projectors, but see use in residential lighting and retail lighting as well. They are suited to applications that require directional lighting such as track lighting, recessed ceiling lights, desk lamps, pendant fixtures, landscape lighting, retail display lighting, and bicycle headlights. MR lamps are designated by symbols such as MR16 where the diameter is represented by numerals indicating units of eighths of an inch. Common sizes for general lighting are MR16 and MR11, with MR20 and MR8 used in specialty applications. Many run on low voltage rather than mains voltage alternating current so require a power supply.

<span class="mw-page-title-main">Infrared heater</span> Device designed to create radiative heat

An infrared heater or heat lamp is a heating appliance containing a high-temperature emitter that transfers energy to a cooler object through electromagnetic radiation. Depending on the temperature of the emitter, the wavelength of the peak of the infrared radiation ranges from 750 nm to 1 mm. No contact or medium between the emitter and cool object is needed for the energy transfer. Infrared heaters can be operated in vacuum or atmosphere.

<span class="mw-page-title-main">Bi-pin lamp base</span>

A bipin or bi-pin is a type of lamp fitting. They are included in the IEC standard "IEC 60061 Lamp caps and holders together with gauges for the control of interchangeability and safety". They are used on many small incandescent light bulbs, and for starters on some types of fluorescent lights.

<span class="mw-page-title-main">LED lamp</span> Electric light that produces light using LEDs

An LED lamp or LED light bulb is an electric light that produces light using light-emitting diodes (LEDs). LED lamps are significantly more energy-efficient than equivalent incandescent lamps and can be significantly more than most fluorescent lamps. The most efficient commercially available LED lamps have efficiencies of 200 lumen per watt (Lm/W). Commercial LED lamps have a lifespan many times longer than incandescent lamps.

<span class="mw-page-title-main">Wedge base</span>

A wedge base is a type of electrical connector used as a fitting for small light bulbs. It is similar to the bi-pin connector, except that the two "pins" are the same wires that extend into the bulb, and the wires are bent up onto the sides of the base, where they make contact with the socket. The wires are usually inserted into a plastic base that the bulb is mounted in, and which is often narrower at the tip than at the bulb, giving it a wedge shape and usually ensuring a tight connection, depending on manufacturing tolerances. Some bulbs have no plastic base, and the wires are simply bent up to the sides of the bulb's glass base.

A lightbulb socket, lightbulb holder,light socket, lamp socket or lamp holder is a device which mechanically supports and provides electrical connections for a compatible electric lamp base. Sockets allow lamps to be safely and conveniently replaced (re-lamping). There are many different standards for lampholders, including early de facto standards and later standards created by various standards bodies. Many of the later standards conform to a general coding system in which a socket type is designated by a letter or abbreviation followed by a number.

<span class="mw-page-title-main">GU24 lamp fitting</span>

A GU24 lamp fitting is a bi-pin connector for compact fluorescent lamps (CFL) or LED lamps that uses a bayonet mount–like twist-lock bi-pin connector instead of the Edison screw fitting used on many CFLs, LED lamps and incandescent light bulbs. The design was initiated by the U.S. EPA and the Lighting Research Center in 2004, in order to facilitate the deployment of compact fluorescent light bulbs with replaceable ballasts.

References

  1. US 931807,"Incandescent Lamp"
  2. 1 2 Matthews, Mike. "How a 3-Way CFL Switch Works". HomeGuides.SFGate.com. Hearst Newspapers . Retrieved March 21, 2022.
  3. Lewis, Bill (December 19, 2022). Campbell, Larry (ed.). "What Is a 3-Way Light Bulb and Socket?". The Spruce . Retrieved January 7, 2023.
  4. Croft, Terrel (1987). Summers, Wilford I. (ed.). American Electricians' Handbook (Eleventh ed.). McGraw-Hill. ISBN   0-07-013932-6.