Minimum thicknesses of enclosure Polymeric Material Polymeric Material The encapsulation Epoxy as watertight Enclosure A one-piece, molded coil form in contact with water Minimum Thickness 1/8 inch (3.2 mm) 1/32 inch (0.8 mm) Minimum thicknesses of enclosure metal At curved, ribbed, or otherwise reinforced surfaces and at surfaces of a shape or size, At surfaces to which a At surfaces intended At unreinforced, flat or both, to provide the necessary mechanical wiring system is to be for Metal surfaces in general strength connected in the field outdoor useCast Metal Nonferrous Die-cast metal such as Aluminum- , Magnesium-, 5/64 inch (2.0 mm) 3/64 inch (1.2 mm) - - Zinc- or Copper- based alloy Ferrous Cast malleable 3/32 inch (2.4 mm) 1/16 (1.6 mm) - - iron Ferrous or Other cast metal 1/8 inch (3.2 mm) 3/32 inch (2.4 mm) - - NonferrousSheet Ferrous Uncoated sheet 0.026 inch (0.6 mm) 0.032 inch (0.81 mm) 0.032 inch (0.81 mm)Metal steel Galvanized 0.029 inch (0.74 mm) 0.034 inch (0.86 mm) 0.034 inch (0.86 mm) sheet steel Nonferrous Sheet aluminum 0.036 inch (0.91 mm) 0.044 inch (1.2 mm) - Sheet copper or 0.033 inch (0.84 mm) 0.043 inch (1.09 mm) - sheet brass - Surfaces in relatively small areas or surfaces that are curved, ribbed, or otherwise reinforced may be less than the specifications in the first column of thicknesses.
A – Region to be shielded by barrier. This will consist of the entire component if it is not otherwise shielded, and willconsist of the unshielded portion of a component which is partially shielded by the component enclosure or equivalent.B – Projection of outline of component on horizontal plane.C – Inclined line which traces out minimum area of barrier. When moving, the line is always: 1) Tangent to the component, 2) 5 degrees from the vertical, and 3) Oriented so that the area traced out on a horizontal plane is maximum.D – Location (horizontal) and minimum area for barrier. The area is that included inside the line of intersection tracedout by the inclined line C and the horizontal plane of the barrier.
Galvanization (or galvanisation) classically refers to any of several electrochemical processes named after the Italian scientist Luigi Galvani. Now the term generally refers to an electrodeposition process used to add a thin layer of another metal to an item made of steel, in order to prevent rusting. More recently, though, the term has been broadened in common usage to include applying a protective metallic coating to an underlying piece of metal, using a process called hot-dip galvanization, which produces similar results, but which does not employ electrochemical deposition.
A zinc coating, other than that provided on hot-dipped, mill-galvanized sheet steel(ASTM A653/A653M)
Phosphate conversion coating are used on steel partsfor corrosion resistance, lubricity, or as a foundation forsubsequent coatings or painting. It serves as a conversioncoating in which a dilute solution of phosphoric acid andphosphate salts is applied via spraying or immersion andchemically reacts with the surface of the part being coated toform a layer of insoluble, crystalline phosphates.Phosphate coatings are often used to provide corrosionresistance, however, phosphate coatings on their own do notprovide this because the coating is porous. Therefore, oil orother sealers are used to achieve corrosion resistance.
Black Oxide (historical uses of black oxide, Bluing) is aconversion coating formed by a chemical reaction produced whenparts are immersed in the alkaline aqueous salt solution operated atapproximately 285 °F (141 °C). The reaction between the iron of theferrous alloy and the hot oxide bath produces a magnitite (Fe3O4) onthe actual surface of the part. It is possible to oxidize non-ferrousmetals under suitable conditions to form black oxides.Black oxide provides minimal protection against corrosion, unlessalso treated with a water-displacing oil to reduce wetting andgalvanic action.The oldest and most widely used specification for hot black oxide isMIL-DTL-13924, which covers four classes of processes for differentsubstrates. Alternate specifications include AMS 2485, ASTM D769,and ISO 11408.
Conversion coatings are coatings for metals where the part surface isconverted into the coating with a chemical or electro-chemical process.Examples include chromate conversion coatings, phosphate conversioncoatings, bluing, black oxide coatings on steel, and anodizing. They are usedfor corrosion protection, increased surface hardness, to add decorative colorand as paint primers. Conversion coatings may be very thin, on the order of0.00001". Thick coatings, up to 0.002", are usually built up on aluminiumalloys, either by anodizing or chromate conversion.Passivation is the process of making a material "passive", usually by thedeposition of a layer of oxide on its surface. In air, passivation affects theproperties of almost all metals–notable examples being aluminium, zinc,titanium, and silicon. In the context of corrosion, passivation is thespontaneous formation of a hard non-reactive surface film that inhibits furthercorrosion. This layer is usually an oxide or nitride that is a few nanometersthick.
Cadmium platingCadmium plating (Electroplating) is under scrutiny because of theenvironmental toxicity of the cadmium metal. However, cadmiumplating is still widely used in some applications such as aerospacefasteners and it remains in military and aviation specs. Cadmiumplating (or "cad plating") offers a long list of technical advantagessuch as excellent corrosion resistance even at relatively lowthickness and in salt atmospheres, softness and malleability,freedom from sticky and/or bulky corrosion products, galvaniccompatibility with aluminum, freedom from stick-slip thus allowingreliable torquing of plated threads, can be dyed to many colors andclear, has good lubricity and solderability, and works well either asa final finish or as a paint base.
Sand-cast The most widely used casting process, utilizes expendable sand molds to form complex metal parts that can be made of nearly any alloy.
Typical U.S. Power Distribution network Three-phase Single phase Three-phase transformer secondary transformer secondary transformer secondary (U.S. commercial 120/240 V) (U.S. residential 240/120 V) (U.S. commercial 208/120 V and 480/277 V) (Europe et al 230/400 V)
US RESIDENTIAL ELECTRICAL BRANCH CIRCUITS TN System PEN (protective earthing neutral)
Electrical SystemNFPA 70, National Electrical Code
Table 400.4 Flexible Cords and CablesS Hard Service (600 V)SJ Hard Service, Junior (300 V)E Thermoplastic Elastomer (After first letter)T Thermoplastic (After first letter)- No T or E means Thermoset by default.O Oil-resistant. Single “O” means outer jacket only is oil resistant; double “O” means both outer jacket and inner conductor insulation are oil resistantW Weather-resistant. (Both Water and Sunlight resistant, suitable for outdoor use)H HeaterV Vacuum CleanerE Elevator (As first letter)EV Electric VehicleT Tinsel (As first letter)P ParallelNI Non – integral-1 Insulation thickness for Parallel cords, thinnest to thickest. Actual insulation–2 thickness varies with cord type and AWG size-3
Branch Circuit. The circuit conductorsbetween the final overcurrent deviceprotecting the circuit and the outlet(s).
NEC RECEPTACLE RULES SHAPE THE POWER SUPPLYCORD LENGTH OF APPLIANCE IN UL STANDARDS.
If > 50 % , marking Connect Only To ADedicated Branch Circuit.applicable.
The intent is to ensureenough slack for theterminal connections to bemade easily.
ARTICLE 314— OUTLET, DEVICE, PULL,AND JUNCTION BOXES; CONDUITBODIES;FITTINGS; AND HANDBOLES314.16 Number of Conductors inOutlet, Device, andJunction Boxes, and Conduit Bodies.(B) Box Fill Calculations. UL 778
ARTICLE 430— MOTORS, MOTOR CIRCUITS,AND CONTROLLERS430.12 Motor Terminal Housings.Table 430.12(B) UL 778
ARTICLE 430— MOTORS, MOTOR CIRCUITS,AND CONTROLLERS430.12 Motor Terminal Housings.Table 430.12(C)(1) and Table430.12(C)(2) UL 778
Electrical Rigid Metal Conduit (RMC) Intermediate Metal Conduit (IMC) Electrical Metallic Tubing (EMT) RMC is the heaviest-weight and thickest-wall steel conduit. IMC has a thinner wall than RMC and weighs about one-third less than RMC. EMT is the lightest-weight and thinnest-wall unthreaded steel conduit and also commonly called thin-wall conduit.