electric motor commutator cleaning

Before we get into specific types of boxes

Before we get into specific types of boxes, let’s go over some things that are applicable to all types of electrical boxes.All electrical connections must be contained inside an electrical box. The box shields the building material and other flammable materials in the event of electrical sparks.All boxes must be accessible. Never cover a box with drywall, paneling or other wall coverings.If an electrical junction box holds only spliced wires and no device, such as a switch, it should be covered with a blank cover plate.An electrical box should be installed with the front edge flush with the Dc Motor Commutators Manufacturers  finished surface of the wall or ceiling.

If the space between the finished surface and the edge of the box is greater than 1/8”, then a box extender should be installed.Make sure your box is deep enough to avoid crowding the wires. It must be deep enough so a switch or receptacle can be installed easily without crimping or damaging the wires. Electrical codes determine how many wires of what size each size of box can accommodate based on the cubic-inch capacity of the box. For example, a #14 wire occupies 2 cubic inches and a #12 wire occupies 2.25 cubic inches. When counting wires, count the fixture or device as one wire. It’s always safe to use a large box unless you don’t have room in the wall or ceiling. There is a chart on the Junction Boxes page at Ask-The-Electrician.com that shows the size of different boxes and the wires they will accommodate.Electrical boxes come in different materials and different shapes. By familiarizing yourself with the different types of boxes, you’ll be able to select the correct box for your home wiring project. MATERIALSIndoor boxes are usually either plastic or metal.Plastic:Plastic electrical boxes are the most widely used boxes for indoor residential wiring. They’re inexpensive and easy to install. However, since you cannot ground a plastic box, so some local codes do not allow them or they are only allowed for certain uses. Check with your local building department before using a plastic box.Some plastic boxes have holes w/knockout tabs.

These boxes do not have built-in clamps so the cable is not held in place by the box. You must use cable clamps and staple the cable within 8 inches of the box if you use this type of box.Plastic boxes are easier to damage than metal boxes, so buy extra boxes just in case. Never install a cracked box.Most are brittle; don’t use them where they are not built into the wall. The exception is an outdoor box made of extra strong PVC.Don’t use with heavy light fixtures and fans.Some plastic boxes include nails for anchoring the box to the framing material.Metal:Metal electrical boxes are stronger and provide better ground connection than plastic boxes.  Metal boxes must be grounded to the circuit grounding system. Connect the circuit grounding wires to the box with a pigtailed green wire and wire nut, or with a grounding clip.The cable entering a metal box must be clamped.“Gangable” boxes can be dismantled and ganged together to make space for two or more devices.

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