Type AC cable is approved by the NEC for use only in dry locations. In order to comply with the NEC for use in wet cash basis vs accrual basis accounting locations, interlocked Type MC Cable must have a corrosion resistant jacket and wet location rated conductors.
Electrical cable encased in metal sheathing is often used in basements and other areas where the wire is not encased in a finished wall. It is handled differently than standard Romex® (non-metallic sheathed) cable. It is often used in fire-rated occupancies as an alternative to metallic conduit. Now AC cable cannot be used in exterior or damp locations.
NM cable, too, presents the danger of nicking inner wires. But because the outer sheathing is softer, less force is required to cut it. With this method, there is the danger of nicking the insulation on the inner wires, not to mention lacerating your fingers on the sharp metal armor. After you insert the cable into the tool’s groove, you turn the handle to cause the cutting wheel to cut away the metal sheathing. The tool is calibrated to cut the metal but stops short of touching the inner wires.
In schools and residential occupancies, this could lead to easy access by children who pull up the carpet. No, the use of a portable device that would be placed over the handle of a circuit breaker for applying a lock is not permitted. These devices are not designed to remain in place with or without the lock installed. This type of device must be removed in order to close a panelboard cover and in some cases must be removed in order to remove bx cable definition the panelboard deadfront. In the case of a two-pole 30A circuit breaker, an accessory device must be purchased from the circuit breaker manufacturer and installed over the circuit breaker. All manufacturers of circuit breakers have a line of accessory devices that include a means to apply locks. These devices will be placed over the circuit breaker before the deadfront goes on and will remain in place with or without the lock applied.
Wiring in locations that are subject to “physical damage” will need protection. But what that protection is will depend on where the wires are installed and the environment of the installation. BX cable is heavy and its surface is corrugated, making it difficult to pull through the holes in studs. BX cable’s metal sheathing can be hard to cut without nicking or severing the inner wire.
As a do-it-yourself residential electrician, you likely will find it easier to handle, rip, and pull NM, or Romex brand, electrical cable. Unless the specifics of the job or the electrical code demand that you use BX cable, your wiring project will go faster with NM, plastic-sheathed wiring. BX is one of the earliest types of electrical cable developed for both residential and commercial uses in the early part of the 20th century. BX is contrasted with a newer cable, NM, which stands for “non-metallic.” Instead of the metal sheathing, NM has a slick vinyl covering that is easy to rip and to pull through holes in studs.
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If the fiber-optic cable in a system needs extra protection, there is an alternative to using conduit or a bonded and grounded conductive cable, such as an all-dielectric armored cable. Because all-dielectric armored cable has no metallic components, there is no need to ground or bond the cable. Type MC Cable without an outside nonmetallic jacket can be installed in an “other space used for environmental air” in accordance with Section 300.22. These cables can be installed either indoors or outdoors and in exposed and concealed locations.
- Section 250.118 permits the armor of Type AC cable to be used as an EGC in accordance with 320.108, which requires an adequate path for fault current.
- Type AC cable is required to have an armor of flexible tape with an internal bonding strip of copper or aluminum in intimate contact with the armor for the entire length.
- BX cable definition, a cable consisting of wires contained in a flexible metal tubing, used chiefly in wiring buildings and in supplying electric power to equipment.
- The definition sends the NEC user to Section 320.100, Construction, for information.
General use MC cables cannot be used in wet locations but there are some types of specialty MC cables that can. The most common is the PVC coated, sunlight resistant, direct burial listed MC cable in the image. It is acceptable to the latest version of the National Electrical Code .
BX CableNM CableRippingBX is difficult to rip back without a special tool.NM is far easier to rip back. Better yet, use a special armored cable cutting tool.NM cable can be cut with a lineman’s pliers or even with the cutter on a wire stripper.CodeBX is accepted by the National Electrical Code . Older BX cables without an internal bonding strip are not accepted by NEC.NM cable is also accepted by the NEC. a cable consisting of wires contained in a flexible metal tubing, used chiefly in wiring buildings and in supplying electric power to equipment.
Use metal-clad with a metal sheath specifically listed as impervious to water, or underground feeder/branch circuit cable , either by itself or in a conduit bx cable definition system approved for use in wet locations . Connect the wires to your switch/outlet/splice in the electrical box.Repeat for the connections at the other end.
If old BX wiring is in good condition and can carry today’s higher power demands, there is usually no reason to replace it. Unlike the older knob-and-tube wires from the early 20th century, the wire sheathing will not turn gummy and degrade over time.
Cutting Bx By Hand
Larger circuit breakers can be custom ordered with a means to apply a lock installed on the circuit breaker itself. The text size in a warning label and the location are based on many factors including, but not limited to, the intended viewer and to ensure a safe viewing distance. These colors, while not specifically addressed in the NEC, are universally understood and must be adhered to for field-applied warning labels. Making labels on your own without following these guidelines could subject the label-maker to future liability concerns. The required label in 450.14 is not a field-applied hazard marking, and the requirements of 110.21 would not apply. Perhaps a future edition of the NEC could include annex material to provide the NEC user with the necessary information to build custom labels.
The installation and construction requirements for Type AC, “armored cable” are located in Article 320 of the NEC. Many in the industry may still incorrectly refer to Type AC as BX cable. Edwin Greenfield and ledger account Gus Johnson developed basic armored cable in the early 1900s. The abbreviation BX has stuck to all metal-jacketed cables for decades. Type AC cable, as constructed today, is a significantly improved product.
Where MC Cable may be used in exterior applications but must be suitable for exterior or direct burial. This type of MC Cable will have a continuous PVC outer jacket. One was called “AX” and the other “BX,” with the “X” standing for “experimental.” The “BX” version became the one that eventually was produced, and hence the name “BX” became the common name. This is to allow access to the wiring method without pulling up wall-to-wall carpeting. The use of this product in a commercial occupancy lends itself well to adding and removing floor outlets on a regular basis. Typically, removable carpet squares are not the type of floor covering applied in residential, school and hospital occupancies. The use of removable carpet squares makes access to FCC easy, as one need only pull up one corner of the carpet square.
When doing electrical projects on your home, generally you will be using NM, or non-metallic, electrical cable as it is easy to handle and inexpensive. But occasionally you might open up a wall or ceiling and encounter a type of metal-clad cable called BX.
Section 250.118 permits the armor of Type AC cable to be used as an EGC in accordance with 320.108, which requires an adequate path for fault current. BX cable definition, a cable consisting of wires contained in a flexible metal tubing, used chiefly in wiring buildings and in supplying electric power to equipment. Cut a 20 centimeter (7.9 in) length of the armor using either a hacksaw or a rotary cutter designed for the purpose. When the cut is nearly through, grab the cable jacket above and below the cut and twist sharply – this should break the remaining armor without the need for the saw to contact the wires inside. Use caution – the metal edges are sharp.Carefully inspect the interior insulation to make sure none of the conductors have been exposed by nicks or gashes. If there is damage, you may need to try again by moving back and redoing another cut.
Section 320.2 defines Type AC cable as a fabricated assembly of insulated conductors in a flexible, interlocked metallic armor. The definition sends the NEC user to Section 320.100, Construction, for information. Type AC cable is required to have an armor of flexible tape with an internal bonding strip of copper or aluminum in intimate contact with the armor for the entire length.
Previous … The metal sheathing of BX cable acts as the ground; a thin metal bonding strip helps ensure a conductive connection. Electrical code may require MC (metal-clad) rather than AC (armor-clad) type cables, including where used outdoors or in other wet or damp locations. Often small pieces of metal will break off and they can be very sharp.
While widely used in the past, BX cable is not relegated to the past. Even with new projects, you still have the choice of using either metal-armored bookkeeping BX cable or plastic-sheathedNM cable. PVC coated, sunlight resistant, direct burial rated MC cable can be used in a wet location.
But safety of an existing BX system does depend on its age, type and how it was installed. I still have no power I suspect there could be a bigger problem,this is aluminum wiring. Basic armored cable was developed in the early 1900s by Harry Greenfield and Gus Johnson, who called their product BX cable. But their names are not the source of the word cabal, which was in use decades before Charles II ascended the throne. The term can be traced back through French to cabbala, the Medieval Latin name for the Kabbalah, a traditional system of esoteric Jewish mysticism. The National Electrical Code prohibits use of BX ( technically named Armored Cable/AC ) in wet locations.
NM cable and wiring must always be installed in an enclosed location . Always be sure to check with your local building and electrical codes as to whether BX cable may be left exposed. Metal-clad cable comes in several varieties, but the type you’ll find at most home centers is three insulated wires protected by a flexible armor usually made from aluminum. MC cable is identified by the gauge of the wire, not the diameter of the armor. The biggest difference between the two cable systems is that MC has full size ground wire while AC uses a combination of the jacket and a thin bonding strip or wire to function as the equipment ground. The bonding wire is unique to AC cable and this allows the outer metal armor in conjunction with the bonding wire to be used as an equipment ground. There were originally two initial versions of armored cable.
Another distinction is that some types of BX cable can be installed in exposed locations, either indoors or outdoors. Ensure that the local authorities permit the use of BX cable in your application. There are many types of armored cables — not all of them may be acceptable for use in all circumstances.Make sure you have the proper connectors for the selected https://personal-accounting.org/ type of cable. Some types may work for several cables types, others may be prohibited. A flexible package consisting of an armor jacket wrapped around wire conductors forming an easily installable wiring system. Similar to MC, AC has an overall Mylar wrapping over all the wires to provide protection and therefore doesn’t require the use of Anti-Short Bushings.
Like any other cable, if the armor is nicked, cut, or shredded, the wires inside can be compromised. BX’s armor, while much stronger than NM’s vinyl, can still be pierced by a determined and ill-placed nail or screw. However, with the exception of electrical wires that run through rigid metal conduits, no other type of electrical cable has as strong an outer casing as does BX cable. BX’s metal sheathing runs in a helix-like or twisted manner around the wires. At first glance, the electrical conduit may seem similar to BX (or AC, for “armored cable”) wiring. Like conduit, loose but insulated individual wires are encased in BX’s metal shell. A chief distinction between BX and NM is that BX can achieve grounding through the outer metal casing.