Washington State Department of Ecology

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Thermostats, Switches and Other Electrical Devices

Thermostats

A thermostat is a type of switch that is controlled by temperature changes. Metallic mercury is in an ampoule attached to a bimetal sensing element.

Thermostats that contain mercury should be managed under the universal waste requirements or as dangerous waste.

  • Digital or programmable thermostats do not contain mercury.

For more information refer to Universal Waste Rule for Mercury-containing Equipment and Thermostats, Revised December 2005, #98-407b.

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Switches and Other Electrical Devices

Mercury-containing devices (equipment), including many types of electrical switches, can be managed as universal wastes, similar to thermostats.

Tilt switches cause something to happen when mercury in the switch responds to movement. Examples of tilt switches in everyday use are include:

  • Chest freezer lights
  • washing machine (older models) lids
  • clothes irons
  • automobile trunk and hood courtesy lights
  • Buildings may have tilt switches used in sump pumps, silent light switches, portable heaters, flow meters, gas meters, security system applications, gas appliances and thermostats.

Rectifiers are devices that convert alternating current to direct current. They may contain mercury.

Relays are devices that open or close electrical contacts to control the operation of other devices in the same or another electrical circuit.  Relays are often used to turn on and off large current loads by supplying relatively small currents to a control circuit.  Many relay devices contain large amounts of mercury.

Gauges such as manometers, barometers, blood pressure and vacuum gauges contain mercury. Liquid mercury in the gauge expands or contracts in response to air pressure in a precise way that can be read on a calibrated scale. Thermometers measure temperature with a bulb of liquid mercury that can expand or contract as the temperature changes.  Non-mercury thermometer alternatives are:

  • Newer thermometers with red liquid contain alcohol instead of mercury.
  • Digital thermometers do not use mercury.

Pilot light sensors on some gas powered appliances such as furnaces and water heaters contain a liquid mercury sensor on a probe attached to the gas control valve.

Electric Wiring Insulation, Panel Partitions and Cloth are known to contain asbestos.

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Asbestos, Lead, and PCBs

Asbestos insulation was used for electrical wiring and panels.

Lead shielding is used in electrical and electronic equipment and in power and communications cable coverings.

PCBs (polychlorinated biphenyls) were widely used before 1979 to insulate electrical equipment such as capacitors, switches and voltage regulators.

The following brief description of non-liquid electrical PCB use was taken from the Federal Register of  December 10, 1999 (Volume 64, Number 237) Environmental Protection Agency, Proposed Rules, Toxic substances; Polychlorinated biphenyls (PCBs)-- Non-liquid PCBs; use authorization and distribution in commerce, 69358-69364 [FR Doc. 99-32079]. It is available on EPA PCB Home Page

  • Plastics, small foam rubber and rubber parts, adhesive tape, and insulating materials used in electrical cabling. PCBs may be in many of the components of electric cable at concentrations ranging from <1 ppm PCBs to 280,000 ppm PCBs (Refs. 15 and 16). In addition to electrical applications, these components may be in widespread use in marine and industrial applications. It is not clear whether PCB-containing cables would be found in residential settings.

PCB Trade Names

Aroclor Dykanol Noflamol
Chlorentol Inerteen Pyranol
Therminol Chlorophen Chlorextol
Clophen Colphen Fenclor
Kanachlor Kanechlor Montar
Pyralene Santotherm Santotherm FR
Sovol Therminol FR  

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Possible Dangerous Waste Codes

For mercury thermostats:
  • D009 (federal toxicity characteristic for mercury), because the metallic mercury in the ampoule is 100% mercury and would leach 0.2 or more milligrams per liter on a TCLP Test.

For switches and electrical devices:

  • Asbestos and PCBs do not have a dangerous waste code because they are regulated by the Toxic Substances Control Act, not the Dangerous Waste Program.
  • WPCB (Washington State only PCBs from discarded (undrained) transformers, capacitors, bushings or certain of their wastes if they contain concentrations of 2 parts per million or greater). PCBs were used before 1979 in the capacitors inside fluorescent light ballasts.
  • WP01 or WP02 (Washington State only persistent criteria waste) for PCB's greater than 100 parts per million. These would most likely be regulated under the federal Toxic Substances Control Program as PCB wastes.
  • WSC2 (Washington State solid corrosive characteristic)
  • D003 (federal reactive characteristic) dangerous waste code.
  • D006 (federal toxicity characteristic for cadmium) if there were enough cadmium to leach 0.2 or more milligrams per liter on a Toxicity Characteristic Leaching Procedure (TCLP) Test.
  • D008 (federal toxicity characteristic for lead) if there were enough lead to leach 5.0 or more milligrams per liter on a TCLP Test.
  • D009 (federal toxicity characteristic for mercury) if there were enough mercury to leach 0.2 or more milligrams per liter on a TCLP Test. The metallic (100%) mercury in gauges and thermometers can be seen and identified as a D009 federal dangerous waste.
  • Asbestos does not have a dangerous waste code because it is regulated by the Toxic Substances Control Act, not the Dangerous Waste Program.
  • PCBs in specific electrical devices that are regulated by the Dangerous Waste Program have a WPCB dangerous waste code.

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Universal Waste Disposal Option

Either recycle or dispose of mercury thermostats as Universal Wastes or as Dangerous Waste.

Refer to the publication Universal Waste Rule for Mercury-containing Equipment and Thermostats, Revised December 2005, 98-407b for more information.

Follow Washington State's Universal Waste rule instead of the U. S. Environmental Protection Agency's Federal Universal Waste Rule .  The EPA's Office of Solid Waste has a website for the Federal Universal Waste Rule at http://www.epa.gov/epaoswer/hazwaste/id/univwast/uwr_fr.pdf

Household Thermostats, Switches and Other Electrical Devices

Electrical devices generated by homeowners or in residences are not Dangerous Waste due to the Household Hazardous Waste Exclusion.

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