- #Plaster rings and domed coveres code#
- #Plaster rings and domed coveres plus#
- #Plaster rings and domed coveres free#
Metal boxes usually have a means for connecting the box to an equipment grounding conductor. Volume of boxes is based on total volume of assembled sections including plaster rings or covers with marked volumes. The attachment of a metal cover or plate to an effectively grounded enclosure or device usually fulfills this requirement. Specifically, 250.110(5) requires that a metal box or enclosure be grounded if supplied by a metal raceway, metal-clad or metal-sheathed cable, or other wiring method that includes an equipment grounding conductor. NEC 250.110 specifically requires that exposed non–current-carrying metal parts of fixed equipment be grounded by connection to the equipment grounding conductor. Metal boxes, covers, or cover plates are required to be grounded. This crude practice can result in damage to the box and inadequate support of the attached cover, luminaire, or equipment itself. This means the use of drywall screws or sheet-metal screws for attaching covers, luminaires, or other equipment to boxes is unacceptable.
Screws used for the purpose of attaching covers, or other equipment, to the box are required to be either machine screws matching the thread gauge or size that is integral to the box, or must be in accordance with the manufacturer’s instructions. Minimum internal depth requirements for outlet and device boxes with enclosed devices or utilization equipment A box or conduit body reduces the likelihood of adjacent combustible materials being ignited by heat or arcing (see NEC 314.25 and 410.22). This type of failure often starts with a loose connection, and may result in a great deal of heat and be accompanied by arcing. One reason behind this rule is that if a failure occurs, it is likely to occur at a joint, splice, or termination. In completed installations, each box is required to have a cover, faceplate or luminaire canopy. Other boxes that enclose devices or utilization equipment are to be sized based on the supply conductors that supply the devices or utilization equipment (see Table 1). Large equipment is defined as devices or utilization equipment that projects more than 48 mm (1 ⅞ in.) rearward from the mounting plane of the box.
#Plaster rings and domed coveres plus#
Boxes that enclose large equipment are required to have a depth that is not less than the depth of the equipment plus 6 mm (¼ in.). Outlet boxes that do not contain devices or utilization equipment are permitted to have an internal depth of less than 12.7 mm (½ in.).
#Plaster rings and domed coveres free#
All boxes (enclosures) must be large enough to provide for sufficient free space for all conductors and devices that will be enclosed within them to prevent overcrowding and possible physical damage when the devices or splices are installed or completed.
#Plaster rings and domed coveres code#
The Code includes general requirements for boxes, such as sizing and support provisions. Let’s look closer at these requirements for box fill calculations. Most of these requirements can be found in Article 314 (Outlet, Device, Pull, and Junction Boxes Conduit Bodies Fittings and Handhole Enclosures).
The National Electrical Code ( NEC) contains sufficient rules and requirements that apply to box fill calculation requirements. The same principle applies to conductors enclosed in a confined space, such as a switch box. A crowded elevator heats up fairly quickly because you and the other heat radiators (bodies) don’t have ample room to dissipate the produced body heat. These conductors must have ample free space to allow proper dissipation of heat from the conductor to not cause damage to the surrounding insulation of these said conductors. One might say, “OK, what’s the big deal what’s the harm?” When put to work carrying the load they are intended to carry (such as a lighting load), the enclosed conductors produce heat from current flow associated with these loads. Unfortunately, these over-crowded boxes are all too common at both residential and commercial applications. More conductors, devices, fittings, etc., are often installed in a box than what that particular box was designed and listed to contain. One of the most frequently encountered Code violations, in my experience, would have to be those concerning box fill requirements.
0 kommentar(er)
