What is NM cable used for?
Anytime you see the term NM cable, it refers to this kind of wiring—individual conductors contained in a bundle protected by vinyl plastic sheathing. For homeowners and professional electricians running new circuits or extending old circuits inside walls and ceilings, NM cable is the material normally used.
What does nm mean in electrical wiring?
Despite the NM label, the individual electrical conductors within the cable are indeed metal—normally copper that is jacketed with color-coded PVC (polyvinyl chloride). The individual conductors normally have black, white, and red insulation. Also present within the NM cable is a bare copper grounding wire.
How many wires can an nm connector hold?
Most NM-connectors are approved for securing only one or two cables, but there are connectors listed to handle even more. The configuration shown above, where a cluster of wires enters the top of the box through a single opening, is called a chase nipple.
Where is the nm-connector located?
Also, shown below is a typical NM-connector—viewed from the side that typically would be on the outside of the panel. Each cable is fastened within 12-inches of the outer end of the raceway. The raceway extends directly above the panel and does not penetrate a structural ceiling.
What are NM type connectors commonly used for?
NM is normally used in one- and two-family dwellings, and certain multifamily dwellings. NM-B is what you will see when shopping for NM cable, which is rated for 90 degrees C (194 degrees F). There are many different ways to wire a dwelling during initial construction using NM cable.
What is NM cable?
Sometimes known as "Romex," named for one of the common brand names, NM cable is a flexible electrical cable that features an outer plastic sheathing that protects two or more insulated conductors, as well as a bare copper ground wire.
How do you use nm clamps?
To install this type of clamp, insert the threaded end into a knockout hole in the box, then thread on the locknut onto the threaded end from inside the box. Tighten the nut with pliers. Insert the cable through the clamp saddle and into the box, and tighten the screws on the saddle to secure the cable.
How do you use plastic nm connectors?
0:001:08NM94X - YouTubeYouTubeStart of suggested clipEnd of suggested clipThey're the lowest cost NM cable connectors on the market. And the fastest to install. Simply pushMoreThey're the lowest cost NM cable connectors on the market. And the fastest to install. Simply push the connector into the knockout.
Where can NM cable not be used?
Type NM cables shall not be used under the following conditions or in the following locations: Where exposed to corrosive fumes or vapors. Where embedded in masonry, concrete, adobe, fill, or plaster. In a shallow chase in masonry, concrete, or adobe and covered with plaster, adobe, or similar finish.
Where can you install NM cable?
It could be installed exposed in a residential garage or in an attic or basement. In most cases, the NM cable must closely follow the building surface or another means of support for the cable must be provided.
How do you install a clamp connector for NM cable?
0:181:08IDEAL Quick Snap NM Connector - YouTubeYouTubeStart of suggested clipEnd of suggested clipSimply insert the inum cable from outside the box. And the fitting provides a strain relief thatMoreSimply insert the inum cable from outside the box. And the fitting provides a strain relief that securely holds the cable. And can be used with 14.
How many nm cables does a clamp have?
Most NM-connectors are UL-approved for securing only one NM-cable to a panel box. But some are rated for two #14 or #12 cables, and we know of one 3/4” connector that is rated for three. Check the box for the number approved by the manufacturer, but it's definitely not more than three.
Can you run Romex into a metal box?
Metal boxes can also be used with Romex or NM wiring if desired, though special precautions must be taken to ensure proper grounding. Contact between an attached device (such as a light switch or outlet) and the metal box completes the grounding contact.
How do you install a plastic Romex connector?
1:237:09Romex® Basics - YouTubeYouTubeStart of suggested clipEnd of suggested clipAnd they work relatively simply all you do is put the cable into the connector. So it's a little bitMoreAnd they work relatively simply all you do is put the cable into the connector. So it's a little bit past the end flip this up. And just crimp it little players.
Is it permissible for NM to enter directly into the panel without fitting or clamp?
What are the requirements for NM-cables entering an electric panel box? NM-cables must be securely fastened where they enter an electric panel, so that tugging on a cable from outside the box will not pull wires loose from their terminations inside.
Can you put two Romex wires one staple?
When stacking multiple Romex wires under one staple, the general rule of thumb is to always wire just one wire per stable, and if you really must, staple no more than two wires side by side. In the field, anything more than two wires at a time is known as a stack.
What is the difference between NM and UF wire?
The primary difference between standard NM and underground feeder (UF) cable is in the cable construction. Standard NM cable contains wires that are wrapped with paper and a relatively loose plastic sheath. UF cable has wires that are completely encased in solid plastic.
Where is MICC cable used?
The main function of MICC cable is to ensure during a fire that all the building emergency and essential circuits such as escape lighting, fire sensors, fire alarm circuits, service lifts, water pumps, smoke extractors continue to function both during the building evacuation and the firefighting efforts.
Can you run nm cable in conduit?
Yes, NM cable can be in conduit. In fact. NEC calls for it to be in conduit, when protection from physical damage is required.
Where is Romex not allowed?
Understanding NEC Regulations with Regards to Romex Romex is a brand name of non-metal sheathing wire. To give you an overview of what the National Electrical Code (NEC) regulations state, Romex wire shouldn't be left exposed anywhere in the house, be it the basement, attic, or the home itself.
What is NM cable?
NM is a type of cable that contains insulated conductors enclosed within an overall nonmetallic jacket. It is commonly known as “ Romex ®”, which is the brand that is most widely used. NM cable contains two or more insulated wires and a bare ground wire. NM is normally used in one- and two-family dwellings, and certain multifamily dwellings. NM-B is what you will see when shopping for NM cable, which is rated for 90 degrees C (194 degrees F).
What is 14-3 NM?
A 14-3 NM cable (3-wire) contains 3 insulated 14 AWG current carrying conductors (black, red, white) and a bare ground wire. The 2 line wires are different phases (A and B) and share the neutral wire for return current.
What type of wire is used for a house?
There are many different ways to wire a dwelling during initial construction using NM cable. The most common type of NM used are 2-wire and 3-wire. A 2-wire NM contains one black wire (usually line) and one white wire (usually neutral) and a bare ground wire. When used in switch wiring, the white wire is sometimes used as a line wire.
What is the white wire used for in a switch?
When used in switch wiring, the white wire is sometimes used as a line wire. A 3-wire NM contains a black, red, white, and a bare ground wire. The black and red wires can be used for line voltage A and B phases, or as travelers in 3- or 4-way switch wiring. 12-2. Wire AWG.
What is NM wire?
The non-metallic (NM) designation refers to the outer sheathing that bundles individual wires together like a cable. This is in contrast to metallic sheathed cable or conduit wiring, in which the bundle of individual conductors is protected by some form of a metal coil or metal conduit. Typically, there are three parts to NM electrical cable: outer ...
What is the color of the PVC in NM cable?
Wire Insulation. Wires within the sheathing are insulated with color-coded PVC (polyvinyl chloride). The individual conductors normally have black, white, and red insulation. Also present within the NM cable is a copper grounding wire that is usually left uncoated and bare but sometimes is coated in green PVC.
What Is Romex Brand Electrical Cable?
Romex is the brand name of a non-metallic (NM) sheathed electrical cable made by Southwire Company, LLC of Carrollton, Georgia.
What is NM sheathing?
One feature of Romex is that it includes SIMpull, an embedded slippery coating on the sheathing that reduces friction when pulling the cable through studs and other difficult passages.
What gauge wire is used for a 15 amp circuit?
NM cable comes in many wire gauges, but most household circuits will use 12-gauge or 14-gauge wire, with either two or three conductors inside (plus the bare copper ground wire). For example, a cable labeled "14-2 with ground" will have two insulated conductors with 14-gauge wires plus a bare copper grounding wire. This cable is used for 15-amp circuits and often powers circuits from panels and individual devices. A cable labeled "12-3 with ground" will have three 12-gauge insulated conductors (white, black, and red) plus the bare copper grounding wire. A 12-gauge cable is rated for 20-amp circuits.
Why is NM wire easier to unspool?
NM wire is easier to unspool and straighten out because the PVC sheathing is pliable. It is easier to pull through holes in studs because of the smooth sheathing. In the case of Romex, a coating is added that makes the sheathing more slippery. NM cable is easier to cut with just a set of side-cutting pliers.
Where is Romex cable made?
Romex is the brand name of a non-metallic (NM) sheathed electrical cable made by Southwire Company, LLC of Carrollton, Georgia.
What is NM cable?
Nonmetallic, or NM, cable (commonly known by the brand name Romex) must be secured to electrical boxes at the point where the cable enters the box. This code requirement is an important safety feature that protects the wiring connections inside the box in case the cable is pulled. It also prevents the cable from rubbing against the edge ...
What is push in connector?
The newcomer on the block is the plastic push-in connector. There are several different designs for these, but basically they are all plastic bushings that snap into the knockout hole in the metal box. The cable is inserted through the connector and secured with a spring-tab or other device. One version includes a little gate piece that you slide down into a slot (similar to the action of a guillotine) then clamp down on the gate with pliers to secure the cable.
How to install a locknut clamp?
To install this type of clamp, insert the threaded end into a knockout hole in the box, then thread on the locknut onto the threaded end from inside the box. Tighten the nut with pliers. Insert the cable through the clamp saddle and into the box, and tighten the screws on the saddle to secure the cable.
How to secure cable in metal box?
Securing Cable With an Internal Clamp . Some metal boxes come with saddle-shaped clamps already mounted inside the box. Usually, there are two clamps that can hold two cables each. If a clamp is not next to the knockout you are using, simply unscrew the clamp and move it to the desired location.
How to remove a knockout cable?
To remove this type of knockout, insert a straight-bladed screwdriver into the slot and twist back and forth until the knockout separates from the box. Another type of knockout has no slot and must be punched out with a hammer and screwdriver. Hit it hard and it will bend down away from the hole (don't worry; you won't hurt the box). Grab the knockout disc with pliers and twist it until it comes free.
What is knockout in electrical box?
Knockouts are the little metal discs covering the holes in the sides or back of a metal electrical box. You remove as many knockouts as you need for the number of cables that will enter the box, and leave the others in place. A box should not have open knockout holes that are empty, as this compromises the protection offered by the box enclosure.
Do cable clamps need to be tight?
Each cable requires its own knockout opening and clamp. Be careful not to tighten cable clamps so much that they crush the cable sheathing or damage the insulation on individual wire conductors. The clamps should be just tight enough so that the cables can't be pulled free by hand. Read More.
Where is NM cable permitted?
The only place in the Code where it specifically permits installing NM cable in a raceway system is the new exception to 334.12 (A) (1) where Type NM cable shall be permitted in Type I and II construction where installed in raceways permitted to be installed in Type I and II construction.
How far can NM cable be supported?
The NEC does not specify a maximum length. The NM cable must be supported within not more than 4½ feet of the fixture, according to 334.30 (B). However, if this accessible ceiling is an occupancy other than one and two family and multifamily dwellings, 334.12 (A) (2) does not permit the use of exposed Type NM cable.
What is NEC 314.17?
NEC 314.17 covers the requirements for securing NM cables to outlet boxes thoroughly, and I can only add 312.5 (C), which requires cables to be secured to the cabinet, cutout box or meter socket enclosure. Be sure you note the Exception to 314.17 (C), where securing cable to a single-gang box may not be required. See section 312.5 (C).
Can NM cable be run in a raceway?
Type NM cable cannot be run outdoors even if it is run in a raceway because this is considered to be a wet location. Type NM cable cannot be run in any raceway other than using it as a sleeve in accordance with 334.15 (B) and 300.15 (C) or in accordance with 334.12 (A) (1) Exception. This exception, which was accepted for the 2008 NEC, permits Type NM cable to be run in Type I and Type II construction where it is installed in a raceway permitted for that type of construction. See sections 334.12 (B) (4), 334.15 (B), 300.15 (C) and 334.12 (A) (1).
Can NM cable be used in a ceiling?
If the accessible ceiling is a space used for environmental air (plenum), Type NM cable cannot be used. See sections 334.30 (B), 334.12 (A) (2) and 300.22 (C) (1).
Can you run NM cable in a raceway?
In my opinion, there is no reason to run NM cable in a raceway other than using it as a sleeve to protect the cable from physical damage. If a raceway system is run complete between outlet points as shown in 300.18, I believe that conductors for general wiring as shown in Article 310 should be used. NEC 334.80 goes to great lengths to determine the permitted ampacities of NM cable where bundled or stacked or in contact with thermal insulation but is silent on the heating effects of NM cable when enclosed in a raceway. Note 9 to Table 1 in Chapter 9 permits a multiconductor cable to be treated as a single conductor when figuring conduit fill and explains how to treat an elliptical cross section but offers no tables showing the approximate diameters.
Overview
Terminology
- Romex® is the specific brand name for a non-metallic (NM) building wire made by Southwire. In other words, Romex® is technically just one brand of NM cable. However, the term Romex is often used generically (though inaccurately) to describe any type of NM cable, no matter which manufacturer made it.
Design
- The NM designation refers to the outer jacket of the cable, indicating that it is a non-metal material. This outer sheathing is a 30 mil-thick PVC jacket that serves to bundle the individual wire conductors together and protect them. This is in contrast to metallic sheathed cable or conduit wiring, in which the individual conductors are instead protected by some form of a metal coil or …
Components
- Despite the NM label, the individual electrical conductors within the cable are indeed metalnormally copper that is jacketed with color-coded PVC (polyvinyl chloride). The individual conductors normally have black, white, and red insulation. Also present within the NM cable is a bare copper grounding wire.
Variants
- NM cable comes in many wire gauges, but most household circuits will use 12-gauge or 14-gauge wire, with either two or three conductors inside (plus a bare copper ground wire). For example, a cable labeled \"14-2 with ground\" will have two insulated conductors with 14-gauge wire plus a bare copper grounding wire. This cable is used for 15-amp circuits. A cable labeled \"12-3 with g…
Advantages
- NM wiring is very common in residential wiring, but it is also possible to wire a home using metallic sheathed cable or conduit. NM wiring has many advantages that make it the most popular type of wiring, especially for homeowners: All factors considered DIY electricians will find their projects easier and cheaper to complete when using NM wiring. Remember, though, that th…
Name
- The Romex name derives from the Rome Cable Corp. of Rome, NY, which originally produced the cable. The company was founded in 1936 and filed for bankruptcy in 2003. Today, the Romex brand is owned by the Southwire company as a trademark. As the company mentions on its website, they \"vigorously monitor and protect the use of the Romex brand.\" In other words, the …