Glossary

The plate on the outside of the motor describing the motor horsepower, voltage, speed efficiency, design, enclosure, etc.

A safety code regarding the use of electricity. The NEC is sponsored by the National Fire Protection Institute. It is also used by insurance inspectors and by many government bodies regulating building codes.

Ventilation using only natural motive force such as wind pressure or differences in air density.

A non-profit trade organization, supported by manufacturers of electrical apparatus and supplies in the United States. Its standards alleviate misunderstandings and help buyers select the proper products. NEMA standards for motors cover frame sizes and dimensions, horsepower ratings, service factors, temperature rises and performance characteristics.

Common indoor pollutant, usually resulting from combustion in gas appliances.

Common indoor pollutant, usually resulting from combustion in gas appliances.

Detector: Infra-red absorption spectroscope.
Advantages: Detectable in 100 ppm concentrations. Well suited to automatic monitoring systems. Disadvantages: Anaesthetic, may be a related health hazard, background concentrations.
The nitrous oxide is a product of rotting vegetable matter and is evolved by nitrogenous fertilisers.

Noise is simply unwanted sound. For this discussion, sound and noise will mean the same thing. Noise is measured with a sound level meter, which measures the sound pressure level. 

Unwanted sound that is obtrusive or interferes with listening. To qualify as interference, noise does not have to be excessively loud.

Noise criteria curves evaluate existing listening conditions by measuring sound levels (preferably at ear level) at the loudest locations in a room. Noise criteria may also be referred to dBA levels.

The amount of noise that is decreased through the introduction of sound absorbing materials. The level (in decibels) of sound reduced on a logarithmic basis.

A switch in which the contacts are closed (contacting) without any external force acting upon it.

A switch in which the contacts are open (separated) when no external forces act upon the switch.

A chemical grouping of nitrogen oxide (NO) and nitrogen dioxide (NO2).

Harmful.

Power generated at a station where the steam to drive the turbines is produced by an atomic process, rather than by burning a combustible fuel such as coal, oil or gas.