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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 ...
The two most common are those sized for standard electrical knockout sizes and those that are for true dimensional holes. A 3/4 inch conduit size punch actually punches a hole that is approximately 1.1 inches diameter for 3/4 nominal size conduit. A dimensional size punch makes a hole very close to the indicated size.
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.
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.
NEMA 1-15P (two-pole, no ground) and NEMA 5-15P (two-pole with ground pin) plugs are used on common domestic electrical equipment, and NEMA 5-15R is the standard 15-ampere electric receptacle (outlet) found in the United States, and under relevant national standards, in Canada (CSA C22.2 No. 42 [1]), Mexico (NMX-J-163-ANCE) and Japan (JIS C 8303).
The maximum voltage allowed by the standard is 1000 V DC or AC; the maximum current, 800 A; and the maximum frequency, 500 Hz. The ambient temperature range is −25 °C to 40 °C. [3] There is a range of plugs and sockets of different sizes with differing numbers of pins, depending on the current supplied and number of phases accommodated.
The size denotes the width of the faceplate for the installed equipment. The rack unit is a measure of vertical spacing and is common to both the 19 and 23-inch racks. Hole spacing is either on 1-inch (25 mm) centers (Western Electric standard), or the same as for 19-inch (482.6 mm) racks (0.625 in or 15.9 mm spacing).
The box pictured top-right is a "Wylex standard" fitted with rewirable fuses. These boxes can also be fitted with cartridge fuses or miniature circuit breakers (MCBs). This type of consumer unit was very popular in Britain until 2001 when wiring regulations mandated residual-current device (RCD) protection for sockets that could "reasonably be ...