Modern wiring systems with NM-B cable usually include a ground wire inside the cable, so the box is not part of the grounding system (however, metal boxes must be connected to the system ground, usually with a short length of wire called a pigtail). Visio Electrical - 370 Visio shapes and symbols in 19 Visio stencils (in both US units and metric units, all in Visio VSS, VSSX and VSDX formats) for you to create drawings of domestic and industrial electrical installations, lighting plans, wiring plans, power generation and distribution, process control and fire and. If you are using a non-metallic cable, such as Type NM-B (non-metallic sheathed cable), then you can use either plastic boxes or metal boxes, as long as the cable is secured to the box with an appropriate cable clamp. Plastic boxes are typically cheaper in price and include built-in clamps for wires. Metal boxes are more durable, fireproof, and secure. If you are using metal conduit to run wiring to the electrical box, then a metal box is required-both to anchor the conduit and because the conduit and metal box itself may be used to ground the system.
Weatherproof metal boxes for outdoor use are generally made of aluminum. Most electrical boxes are either metal or plastic: Metal boxes are generally made of steel, while plastic boxes are either PVC or fiberglass. Best for: Metal-sheathed cable or metal conduit (metal boxes), Romex or non-metallic cables (plastic boxes).The Spruce Home Improvement Review Board.