Common Electrical Conductor Types

bx cable definition

This page is all about the acronym of BX and its meanings as Basic Armored Cable. Please note that Basic Armored Cable is not the only meaning of BX. There may be more than one definition of BX, so check it out on our dictionary for all meanings of BX one by one. These days, I try to officially only call the pre-bonding cable BX, modern stuff I don’t since it has a strip. DisclaimerAll content on this website, including dictionary, thesaurus, literature, geography, and other reference data is for informational purposes only. This information should not be considered complete, up to date, and is not intended to be used in place of a visit, consultation, or advice of a legal, medical, or any other professional. AC-Lite Armored Cable Galvanized Aluminum Armor – Commercial, industrial, multi-residential branch circuits and feeder wiring.

bx cable definition

So to answer your question – Yes just have them install a grounding tail from the metal box to the devcie. EMT and MC are often deployed in the same installation because their uses permitted are nearly identical. It is not uncommon to see single branch-circuit runs that transition back and forth a dozen times between entrance panel and load. Segments are easily joined used set-screw couplings and other fittings except for outdoor installations where compression fittings are required. NM, or “Romex” has generally not been allowed in commercial buildings. While the NEC has loosed a bit in this regard, local rules and trade practices still frown upon it in commercial, or exposed, locations. I witnessed a retrofit of wiring in our head office a few years ago, which is a simple wood-framed building.

It is difficult to pull out old wires or insert new ones. BX is not defined as a term by the NEC and is technically called AC .

None of my receptacles at my house have equipment grounds and I want to add them but had the thought that maybe I could do it w/o having to try to fish NMB into my old boxes. So I would use the old cloth insulated two wire to pull in #14 wires. It’s my house so I thought it would be a good test run for something I haven’t tried before, plus it would be nice to know if this is a viable option for other resi jobs. MC cable uses a different grounding system from true armor cable and may have additional waterproofing.

This is the newest type of metal-covered cable and is found in a wide range of commercial and industrial buildings. If the BX doesn’t contra asset account have the aluminum bonding strip it may not be used for bonding egc, that bonding strip didn’t start showing up until ’59.

Pulling Thhn Through Bx

Find great deals on eBay for bx cable armored cable 12/2. Have any QuickBooks of you tried to pull #14THHN through old two-wire BX cable?

  • I witnessed a retrofit of wiring in our head office a few years ago, which is a simple wood-framed building.
  • BX is also known as Armor Clad or Flexible MetalConduit cable.
  • The plastic sheathing of NM cable does not shield electric fields.
  • The “Greenfield” flexible armor-tubes for electric wiring and its further redevelopment & new patent versions listed by UL are what was and is known as “greenfield”.

Older BX cables without an internal bonding strip are not accepted by NEC. Push a plastic anti-short bushing onto the wires where it contacts the metal armor. You may be required to use bushings that have an indicator tab, tip or tail. Insert a BX connector over the end of the newly cut armor and tighten the screw to secure it to the armor.

Wire is a single electrical conductor, whereas a cable is a group of wires swathed in sheathing. The term cable originally referred to a nautical line of multiple ropes used to anchor ships, and in an electrical context, cables are used to carry electrical currents. A flexible, multi-conductor armored cable having an outer protective covering consisting of a helically wound steel strip; used for connections to electric equipment and in wiring houses.

Ac & Hcf Armored Cables

When used with appropriate conductors, metal-clad cable and electrical metallic tubing havenearly identical uses but quite different workingcharacteristics. Because all-dielectric armored cable has nometallic components, there is no need to ground orbond the cable. It is acceptable to the latest version of the NationalElectrical Code . But safety of anexisting BX system does depend on its age, type and how itwas installed. Here is another reason to use BX over NM cable that can save you well over $1,000. BX is resistant to nails and screws and rodents and other pests.

bx cable definition

So for a small job, the extra cost may only be $100 or so, and even for a large job the extra cost should not exceed $1,000. If the conduit used is PVC, the benefits are the same as NM cable, low Magnetic Fields but no Electric Field shielding. If the conduit used is galvanized steel, the benefits are the same as BX, good resistance to puncture, low MF emittance, bx cable definition and good EF shielding. Since the 1960s, Knob and Tube has not met current electrical code thus any renovations or new construction built in the last 50 years should contain more modern wiring. It is acceptable to the latest version of the National Electrical Code . But safety of an existing BX system does depend on its age, type and how it was installed.

It may be used in some, but not all classified locations. It is permitted in wet locations and underground where identified for such use. Flexible sheathed cable is easier to run through holes in studs than metallic sheathed cable, it is also cheaper. Romex cable is labeled as NM-B, which means the sheathing is non-metallic cable; other brands use code “NMC”. The “NM” designation is used to distinguish it from metallic sheathed cable. Another designation, UF, indicates the cable is rated for direct burial in the ground . Romex™ is a common type of residential wiring that is categorized by the National Electrical Code as underground feeder or non-metallic sheathed cable .

Wire Gauge, Ampacity And Wattage Load

The metalsheathing absorbs the electric fields emitted by the wires andshunts it to ground. 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. Armored cable and Metal Clad cable have a flexible metal armor of similar outward appearance, but that is where the similarity ends. There are three basic types of metal-covered cable; all are referred to as armored cable. This cable type went into production during World War II and saw heavy use for several years.

bx cable definition

Any wiring that is on the exterior of the home needs to be rated for use in damp or wet locations. Basic armored cable was developed in the early 1900s by Edwin Greenfield and Gus Johnson, who called their product BX cable. Some of the prevailing attitudes about the product most likely stem from imperfections inherent in the original BX. Armored cable often refers to all power cables that are covered in metal. True armored cable is essentially just a heavier form of BX. It features a better grounding system and a heavier internal insulation. The process used to cover the cable in its metal covering allows for better waterproofing and an overall tougher design.

What Does Mc Mean In Electrical Terms?

Here are two examples from home inspections of AC/MC cables being used in exterior application that are not appropriate. As you can see they do not have a protective PVC outer jacket that would allow the use on exterior applications.

Power Cable

Without having to go into my attic and look for my old code books, I checked as far back as my 1956 and AC, ACT and ACL (“L” for lead) were the “BX’s” of the day. I don’t believe the term “BX” was ever used in the code book just as “Rome-X” is not used in the code book. Slightly different than NM and NM-B in that NM and NM-B is simply the same wiring method, only the “B” version of it, while “B X” was an entirely new wiring method.

There is at least one company making MC with a thick internal aluminum grounding wire and the armor can be used as the ground. This wire is just internal bonding and gets cut off at the termination. I’ve got to run some wiring in a commercial space for a buddy. Running a branch circuit from an electrical box down to below the floor deck, then across the underside of the floor assembly retained earnings and then up through the deck. Safety is very important, and if your installation of wires and cables is not proper, it could lead to accidents. Before you start any electrical project that includes wiring and cabling, you need to obtain permission from your local building inspector. Once the job is done, get the installation inspected for compliance with local codes and regulations.

Electrical Wiring

Here’s a brief about cables that you need to understand to determine the correct cable for your home. BX is trade jargon for a type of cable, usually means AC, but BX is not a chapter 3 wiring method, IE you can’t find it listed. The dissipated heat from knob-and-tube wiring can pose a fire hazard if the wires are enveloped in building insulation. A possible exception is fiberglass insulation, which is fire-resistant, although even this type of insulation should not cover knob-and-tube wiring. The homeowner or an electrician should carefully remove any insulation that is found surrounding KT wires.

Latest From Code Basics

BX is sheathed in a flexible metal spiral made either from aluminum or galvanized steel. BX provides all the advantages of NM cable plus some additional benefits. The flexible metal sheathing is easy to install, about as easy as NM cable. The wire of choice for feeders and branch circuits in residential locations is Type NM, non-metallic sheathed cable. It is inexpensive, quick and easy to use, and requires a minimum of tools. But its use is prohibited in sensitive locations, so for industrial, commercial, and even some residential locations, electrical designers and installers have to look elsewhere. MC is similar to AC but it has in internal “green wire” ground and a plastic internal wrapper .

I was surpised to see the guys pulling miles of BX; every single branch circuit was BX. I asked why, and got the answer that that was what the engineer spec’d. NM and NMC cables should be secured at intervals that do not exceed 4½ feet, and they should be secured within 12 inches of junction boxes and panels to which they are attached. Cables that do not comply with this rule can sag and are vulnerable to damage. Most likely the neutral wire is white and the hot wire is red or black, but test to make sure. 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.