Why Is It Called Bx Cable?

what does bx cable stand for

The fact it is allowed in any raceway means it is allowed in any raceway. When it is in a raceway it does not have to be secured to the box, it is secured to the raceway. It is acceptable to the latest version of the National Electrical Code .

Inside NM cable, the hot and neutral conductors are side by side, thus NM emits a much smaller, more localized and weaker magnetic field. The magnetic field strength drops very quickly with distance from the NM cable.

Wire Insulation

An MC cutter is needed to cut the sheath with no danger of nicking the conductor insulation. Even the smallest nick in a cable’s insulation during a pull can lead to outer sheath damage and a short circuit fault. Cables that won’t meg properly will need to be completely replaced to resolve the issue. Instead, learn how you can prevent cable faults during installation. Even with new projects, you still have the choice of using either metal-armored BX cable or plastic-sheathed NM cable.

what does bx cable stand for

Grounding here is possible through the separation of the copper ground wire in bundles. You may know it as Romex or house wire, but nonmetallic sheathed cable has become a mainstay of residential wiring since it became available almost a century ago. NM is a quick, easy way to get power where you want it and is relatively cheap compared to other methods of wiring. Romex wiring is mainly employed in residential wiring, although it’s still possible to achieve the task using conduit or metallic sheathed cables.

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You can run romex on the surface of a wall as long as it is not exposed to anthing that will damage the wire. The term hospital grade is not a regulated term and can be used by different manufacturers to mean different thing. Whether or not an insulated throat is part of the listed product, these listed MC fittings do not require an additional anti-short bushing. Anti-short bushings that may be supplied by MC Cable manufacturers are for optional use by the installer, however they are not required.

what does bx cable stand for

I had a shop burn down two years after a licensed electrician made an inadequate crimp on a tongue fitting to stranded wire to a screw terminal on a fan switch. The stranded wire slipped out of the crimp, shorted to the box and overheated the conduit leading to it, starting the fire. I am building a catalogue in MS Access, but have only gott to about 870. It is a long-term project like everything else, it would seem. I have done some wiring around the house – and all in the basement workshop . I bought a couple of books, wandered the isles of few stores to match the stuff on the shelves with the pictures/text in the books – and have been enjoying the results for many years.


Since the PVC sheathing in these Romex wires is pliable, they are easier to straighten and unspool. If you want to connect any devices, you must first strip the wire insulation from copper wire using manual wire strippers. The holes of a wire stripper correspond with various wire diameters. It would be best if you started by cutting across the armor, excluding the spiral. It isn’t necessary at all to cut through the armor completely. The National Electrical Code puts the required minimum amount of cable that should extend past the junction box. Inspectors might ask to view the ‘listing label’ for your BX cable to verify whether it conforms with the local standards and code requirements for cable installation and maintenance.

what does bx cable stand for

Conduit is cheap, gets the job done neatly, and is easy to run. Get yourself a bender and with a little practice you will be turning out professional looking work. There are a number of web sites that can give you information on angles, etc.

When Was Bx Cable First Used?

Of course, nowhere near the 70 amps was ever used or the building might have lit up, but that ‘s how it was. So, to make a long story short, it rarely makes sense to increase the size of your branch wiring. The standard rules (14 gauge/15A, 12 gauge/20A and 10 gauge/30A) should suffice. If you run 30 or 40 amps on 12 gauge wiring, you’re not following the NEC, and that’s why you would have excessive voltage drops. The voltage rating of insulated wire depends solely on the insulation.

  • Splices can be made in light fixture enclosures, wall boxes, or junction boxes.
  • A similar product sheathed with metals other than copper is called mineral insulated metal sheathed cable.
  • The individual conductors, in MC, are not approved for use in other raceways without being in the MC jacket.
  • Inside cables or conduits are individual wires, or conductors, that vary in thickness according to the current they carry.
  • Most modern house wiring is plastic-sheathed cable , but you may find any—or all—of the wiring types described here in older houses.
  • Thermoset XLPE insulation is superior to the thinner PVC insulation used in thermoplastic products (like THHN/THWN-2).

The flexible metal sheathing is easy to install, about as easy as NM cable. These MC wires have interlocked armor surrounding the THHN wires. The aluminum armor also acts as a conduit when used for indoor applications. Many times NMB electrical wire is required to be installed within conduit for indoor applications, but now MC cable can act as the electrical wire and conduit in one.

Using Bx Cables

Be sure to obtain any necessary electrical permits, even if your jurisdiction allows the work to be done by a non-licensed electrician. Romex wiring is permanent wiring in houses and shouldn’t be employed as extension cords and appliance wiring substitutes. The use of devices what does bx cable stand for that might damage cables, including overdriven staples and bent nails, isn’t permitted. In this article, we are going to look at comparisons between BX and Romex wiring. The Romex name comes from Rome Cable Corp. of Rome, New York, which originally produced the cable.

Identify the neutral wire in the fixture by looking at the wires. In most modern fixtures the neutral wire will be white and the hot wire is red or black. In some types of fixtures, both wires will be the same color. Armored cable, or BX, first appeared in the 1903 NEC, but did not start becoming popular until around 1930, and is still a popular wiring method today. The armor of AC cable systems is tested for grounding and can provide a suitable equipment grounding path. Interestingly, the original 140 ft. run to my detached shop/garage building was #10 for a five circuit subpanel totalling 70 amps.

  • We hope to clear up any sort of confusion you might have about these cables and more.
  • Some tests done in 2007 to old AC showed that the insulation samples all passed a 5000 volt test, but the resistance of the sheath tended to be high, maybe over 3 ohms per 100 feet, I think.
  • They should be run through studs, on top of joists or trusses, and secured every six feet or so as well as within 12 inches of any fixtures.
  • 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.
  • If a given wiring situation results in a greater voltage drop, it’s not an NEC violation .
  • Unless the wiring is the modern PVCu coated type, then a rewire is likely to be necessary.
  • NM cable usually contains one or more “hot” (current-carrying) wires, a neutral wire, and a ground wire.

For whatever reason, people really enjoy overthinking electrical stuff. I guess it’s the audiophile tendency that’s in all of us.

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Typically, Romex cable has two insulated wires inside and a ground—which may be insulated or, more often, bare wire. Thus, the Romex used for a standard 15-amp lights-and-outlets circuit will be stamped 14/2 w/grd.

Can I run MC cable outside?

The interlocking metal tape armor Type MC cable is required to have a bare or insulated equipment grounding conductor in addition to any other conductors within the cable. … These cables can be installed either indoors or outdoors and in exposed and concealed locations.

Often small pieces of metal will break off and they can be very sharp. Connect the wires to your switch/outlet/splice in the electrical box.Repeat for the connections at the other end. One reason you don’t put romex in conduit is because it creates more heat and is not advised in conduit if you have conduit you can run insulated wires instead it’s probably cheaper. When you put romex inside conduit The Romex cannot breathe and retains too much heat. Romex is used for most lighting and outlet circuits in your home. The individual conductors, in MC, are not approved for use in other raceways without being in the MC jacket.

Residential Wiring Best Practices

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. While NM cable can be used in some residential remodeling projects, armored cable is now accepted in almost all types of construction by city planning offices and local building inspectors. These cables can be installed either indoors or outdoors and in exposed and concealed locations. They can be direct buried, where identified for such use.

  • 12/2 is used for 20-amp circuits and 14/3 wire has 2 “hot” wires and is rated for 15-amp circuits.
  • This tool costs between $20 and $50 and makes the job of splitting and ripping back BX cable far easier and safer than by hand.
  • If you have to tear out a wall to replace a wire that has been punctured by a nail, supposing you were hanging a picture, this repair could cost well over $1,000.
  • Romex is a type of conductor that has non-metal sheathing.
  • Tray and UFB have slightly different applications so be sure to discuss each situation with your supplier or electrician first.
  • All AC90 is CSA approved and manufactured with two, three, or four copper conductors insulated with RW90 cross-linked polyethylene rated at 600 volts from #14 to #2 AWG.
  • In this article, I will explain current options and residential wiring best practices.

The National Electrical Code prohibits use of BX ( technically named Armored Cable/AC ) in wet locations. The cables are developed with plastic sheathing making them easier to rip. It’s even possible to cut the sheathing using a utility knife and then rip it back with your hand. There is also a copper grounding wire that is left bare and uncoated. There is also paper added within the cable to separate the conductors.