TCLP stands for Toxicity Characteristic Leaching Procedure. It was established by the Resource Conservation and Recovery Act (RCRA). The test is designed to simulate water passing through waste in a landfill and to then measure the toxicity of the "leachate" or water that passed through. This test is used in the lighting industry to confirm that a product qualifies as a "low mercury" product.

Thermal Protection

Intended to prevent an electrical system from overheating. Overheating can reduce performance, shorten life, intensify Transformer Hum, cause unpleasant odors, have unpredictable effects on nearby objects, cause dangerous failure or even cause fires.

See Thermal Protector.

Thermal Protector

Class P thermal protector - "A switch that disconnects ballast if internal temperatures rise to levels > 105°C." - Advance Ballast Glossary

Three-Phase Current

"Current delivered through three wires with each wire serving as the return for the other two." - Advance Ballast Glossary


  • Can be both a verb and a noun. Torque is measured in newtons. The actual measurement of torque isn't used in practice in the lighting industry.
  • Verb: To torque something is to tighten it and to overtorque something is to tighten it too much. Over torquing a bulb can result in damage to the lampholder, separation of the base from the bulb and even the fracture of the bulb shell. If a bulb is torqued to the point of causing the bulb shell to fracture then first of all the bulb was overtorqued and secondly the fracture, which generally will take place in the neck near the base, will often show a characteristic fracture pattern.
  • Noun: The amount of force that is used when turning (twisting) something. In lighting this is mostly applied to the amount of force used to screw a bulb with a threaded base into its lampholder. The smaller the base of the bulb the less torque it can withstanding before damage is likely to occur. In cases where the maximum diameter of the bulb is much larger than the diameter of the base the danger of overtorquing the bulb is much greater. This is why the location on the bulb where the torque is applied is very important. When the same amount of torque is used when screwing in a bulb the location that the twisting force is applied to is very important. When the same amount of force is applied to the point on the bulb with the largest diameter as opposed to the point with the smallest diameter will be far more

Touch Sensor

A capacitance sensor used in many table lamps. It only requires one terminal and detects the increase in capacitance that occurs when a person touches the detection surface.


An electrical device used to change the voltage of alternating current (AC) power systems. Transformers that increase voltage are called "step-up transformers" and those that decrease voltage are called "step-down transformers". Traditional magnetic transformers consist of two magnetic cores (CP & CS) each with a separate wire wound a certain number of times around it (Np & Ns). The magnetic cores used in high intensity discharge ballasts for example are made of stacked electrical steel laminations.
Here's an oversimplified formula for basic transformer theory:
Output voltage = input voltage X Secondary turns over Primary turns
Refer to the drawing below: A transformer supplied with 120 volts (VP) with a wire wound 10 turns (NP) around the primary core (CP) and another wire wound 20 turns (NS) around the secondary core (CS), or in other words twice as many times, will output 240 volts (VS) . Double the turns, double the volts.


The process of determining the cause of a fault in a system that is preventing/interfering with normal operation.


A naturally occurring element with the symbol W. It has a very high melting temperature of 3695 K (3422 °C, 6192 °F). This is the metal that is used to make the filaments in light bulbs.

Tungsten Halogen Bulb

  • A bulb constructed using a tungsten filament but that relies upon a process known as the halogen cycle to produce its characteristic color temperature and efficacy. In order for the halogen cycle to function properly the filament must remain at a sufficiently high temperature and must be highly pressurized with a halogen gas fill that includes traces of halogens. Halogen capsules are much smaller than traditional incandescent bulbs. This is because of the very high pressures that it operates at as well as the very high temperature that it must maintain.
  • Because of the high pressure and temperature necessary for halogen bulbs they must use a material stronger than the standard glass used with traditional incandescent bulbs. The most common materials used are quartz or "hard glass".
  • Because it decreases the temperature and therefore pressure as well, dimming tungsten halogen bulbs prevents the halogen cycle from occurring and therefore shortens the life of halogen bulbs.
  • Color Temperature

    General service halogen bulbs emit color temperatures of 2800-3000K while special Audio Visual halogen bulbs emit color temperatures as high as 3400K.
  • Ultraviolet Output

    Tungsten halogen bulbs emit a small amount of ultraviolet light and thus can over time cause colored dyes, pigments and surfaces to fade. See UV-Block Coating.
  • Warnings

    Because of their extremely high bulb wall temperature tungsten halogen bulbs are very sensitive to contact with anything that interferes with their ability to expel heat. The most notable example is that of oil residue left behind by simply touching the bulb capsule. Within a short time of operation after being touched a halogen bulb will fail due to excessive heat buildup behind the location(s) of the oil. If a halogen bulb capsule is touched the residue can simply be cleaned off by using rubbing alcohol. This cleaning must be done prior to the bulb's continued operation!
  • Halogen IR Bulb

    A subtype of tungsten halogen bulbs.

Twin Tube

A small u-shaped or H style (biaxial shape) tube which is the most common basic compact fluorescent bulb shape.
The DAMAR designation for this style of tube is "TT" or Twin Tube.
The GE trademarked name for this style of tube is "Biax".
The Osram trademarked name for this style of tube is "Dulux".
The Philips designation for this style of tube is "PL".
PL-C (22mm)