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A small metal, plastic or fiberglass junction box may form part of an electrical conduit or thermoplastic-sheathed cable (TPS) wiring system in a building. If designed for surface mounting, it is used mostly in ceilings, concrete or concealed behind an access panel—particularly in domestic or commercial buildings [2].
External pattress boxes: power and data sockets. A pattress or pattress box or fitting box (in the United States and Canada, electrical wall switch box, electrical wall outlet box, electrical ceiling box, switch box, outlet box, electrical box, etc.) is the container for the space behind electrical fittings such as power outlet sockets, light switches, or fixed light fixtures.
The Official Table of Drops, formerly issued by the British Home Office, is a manual which is used to calculate the appropriate length of rope for long drop hangings. Following a series of failed hangings, including those of John Babbacombe Lee , a committee chaired by Henry Bruce, 1st Baron Aberdare was formed in 1886 to discover and report on ...
Below is a list of NEMA enclosure types; these types are further defined in NEMA 250- Enclosures for Electrical Equipment. Each type specifies characteristics of an enclosure, but not, for example, a specific enclosure size. Note that higher numbers do not include the lower-numbered tests. For example, types 3, 4 and 6 are intended for outdoor ...
Polycarbonate, glass-reinforced, and fiberglass boxes are used where stronger cabinets are required, and may additionally have a gasket to exclude dust and moisture. Metal cabinets may meet the conductivity requirements for electrical safety bonding and shielding of enclosed equipment from electromagnetic interference.
Some of the important characteristics of materials are : strength, durability, flexibility, weight, resistance to heat and corrosion, ability to cast, welded or hardened, machinability, electrical conductivity, etc. [3] In contemporary design, sustainability is a key consideration in material selection. [4]
A box truss is a structure composed of three or more chords connected by transverse and/or diagonal structural elements. [1] Application
The ceiling projector or cloud searchlight is used to measure the height of the base of clouds (called the ceiling) above the ground. It is used in conjunction with an alidade , usually positioned 1000 ft (300 m) away and wherever possible set at the same level.