ASME A17.5-2004 pdf free download.Elevator and escalator electrical equipment
3 Construction
3.1 Electrical components used in control equipment shall be suitable for the intended application and shall be either
(a) certified to the requirements of the pertinent standards covering such components; or
(b) specifically evaluated for the intended use.
3.2 Components for electronic circuits such as solid-state devices (SCRs, diodes, etc.), resistors, and capacitors for which there are no appropriate standards may be accepted as components based on examination (quality of work, electrical spacings, etc.) and testing.
4 Enclosure construction
4.1 General
4.1.1 The enclosure of control equipment shall be constructed and assembled so that it will have the strength and rigidity necessary to resist the abuses to which it is likely to be subjected, without resulting in a hazard due to reduction of spacings, loosening or displacement of parts, or other serious defects.
4.1.2 An enclosure shall be constructed so as to reduce the risk of unintentional contact with enclosed electrical devices.
4.2 Thickness of cast-metal enclosures for live parts A cast-metal enclosure of malleable iron and die-cast metal or permanent mould cast aluminum, brass, bronze, or zinc shall be used. It shall be (a) not less than 2.4 mm (0.094 in) thick for an area that is greater than 1 5 500 mm 2 (24 in 2 ) or that has a dimension greater than 1 50 mm (6 in); (b) not less than 1 .6 mm (0.063 in) thick for an area that is 1 5 500 mm 2 (24 in 2 ) or less and that has no dimensions greater than 1 50 mm (6 in). The area limitation may be obtained by the provision of suitable reinforcing ribs subdividing a larger area; and (c) not less than 3.2 mm (0.1 25 in) at reinforcing ribs, door edges, and unthreaded conduit entries. Thicknesses may be reduced if the enclosure complies with the requirements of the impact test of Clause 1 9.5 of this Standard and the conduit connection tests of CSA C22.2 No. 1 4 or UL 508. 4.3 Thickness of sheet-metal enclosures for live parts
4.3.1 Except as specified in Clause 4.3.2, the thickness of sheet-metal enclosures shall be not less than that specified in Tables 1 and 2, except that at the points at which a wiring system will be connected, uncoated steel shall be at least 0.78 mm (0.032 in) thick, zinc-coated steel at least 0.88 mm (0.034 in) thick, and non-ferrous metal at least 1 .1 6 mm (0.045 in) thick.
4.3.2 The thickness of sheet metal for enclosures at points other than those at which a wiring system will be connected need not comply with the thickness requirements of Clause 4.3.1 if the enclosure complies with the compression and deflection test requirements in Clauses 1 9.8 and 1 9.9. Note: Tables 1 and 2 are based on a uniform deflection of the enclosure surface for any given load concentrated at the centre of the surface, regardless of metal thickness.
4.3.3 With reference to Tables 1 and 2, a supporting frame shall consist of a structure of angles, channels, or folded rigid sections of sheet metal. This structure shall be rigidly attached to and shall have essentially the same outside dimensions as the enclosure surface and sufficient torsional rigidity to resist the bending moments that may be applied by the enclosure surface when it is deflected. A structure that is as rigid as one built with a frame of angles or channels is considered to have equivalent reinforcing. Constructions without a supporting frame shall be considered to include
(a) a single sheet with single-formed flanges or formed edges;
(b) a single sheet that is corrugated or ribbed;
(c) an enclosure surface loosely attached to a frame (e.g., with spring clips); and
(d) an enclosure surface having an unsupported edge.ASME A17.5 pdf download.ASME A17.5-2004 pdf free download
