![]() ![]() The main ways you will make electrical connections of wires are by wire connectors ("wirenuts") and at terminals. When it is a romex cable that brings wires into a box (other than a one-gang plastic box), the box will or should have a clamp to hold the cable securely to it.Ĭonnecting wires. ![]() The formula for calculating this " box fill" is somewhat involved. The number and gauge of wires that may be installed in a box will be related to how many devices will be mounted in it and the volume of the box, which is stated inside it (in cubic inches). According to the number of devices that can be mounted in it, a switch/receptacle box will be called one-gang, two-gang, etc. ![]() Boxes are not only a mounting place but minimize shock hazard and the possible effect of sparks or heat. An electrical box is almost always required for mounting devices (switch, receptacle) and light fixtures, and also wherever circuit connections or splices are made - which is usually at the same places. The wires themselves are not to be cut back any shorter than 6 inches from the end of the sheath and must initially be able to extend at least 3 inches outside the front of the box.Įlectrical boxes. In practice, leaving more than an inch of sheath visible starts to interfere with the flexibility of the wires, and space for devices and wire connectors. 25 inches from where it enters the box's interior. Inside the box a cable's sheath is to be removed no closer than. In addition, such support is to be provided within 12 inches of where the cables enter boxes (but within 8 inches of one-gang boxes which have no built-in clamps). This support can consist of holes in the framing or approved staples or wire-ties. These cables are to be secured to the home's framing every 4.5 feet at most. (The listing I have just given is in increasing size order.) It also says "With ground," which means a bare (or even green insulated) wire is in the cable but is not included in the "-2" or "-3" count. On them it says "NM-B," which means non-metallic with wires that can stand 90 degrees of heat (Celcius) before "B" (1985) they were only good for 60 degrees. Your wiring could be done with a conduit system or metal-sheathed cables, but in most places these plastic jacketed cables are the norm for houses and non-highrise apartments. ![]() For issues about some particular appliances see In what I say I am careful to qualify my statements if they have exceptions, using words like "usually" or "typically." If a practice is specified by the National Electrical Code I will tend to indicate this by "is to be," "should," or "must," and I won't talk that way if the matter is just common practice.įor problems with existing wiring, circuits, and connections, be sure to see my These certainly don't cover everything you might want to know. Here I intend to give clear information on a number of basic house wiring issues that may be unfamiliar or confusing to the do-it-yourselfer. Wiring Basics House Wiring Issues, Parts, and Code ![]()
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