30Sep
Bx Cable Definition & Meaning
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Additionally, with the armor wound around the conductors, a ground fault current could create a choke coil effect on the conductors within the outer armored sheath, leading to greater problems. The differences between the three cable types are very minor and often ill-defined, but among the biggest differences are the cables’ grounding systems. BX cable generally goes to ground through the metal sheath, which works well if the cable is buried or covered in some way, but not if it is exposed. Armored cable also grounds through the sheath, but has the ability to ground to predetermined areas, which allows certain portions to be exposed without exposing the grounding system. Lastly, MC cable has a grounding wire inside the wire bundle, allowing users to create a ground wherever they want, which makes the system safe for exposed areas. Type MC also resembles armored cable but there are some subtle differences. MC includes a green equipment-grounding conductor, whereas AC depends upon the outer sheath, with an internal continuous metal strip in contact with the sheath, for equipment grounding.
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 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.
Our editors update and regularly refine this enormous body of information to bring you reliable information. Knowing when and where a type of cabling system can and cannot be used is very important in electrical installations and is often a mark that a professional has not done the work. So “BX” is defined as “AC” cable and “MC” is defined as Metal Clad cable. These two cable assemblies are very similar in construction. Armored or Metal Clad Cables used in exterior installations. HBOGo has become such a massive success for cable network HBO that they will start to offer the service as a stand-alone option.
I have seen greenfield catch fire in a couple of places where it wasn’t installed adequately. One was a commercial bakers type of mixer in a foam type factory. The mixer was raised raised and lowered into the kettle by a gear motor. The 240 volt mixer retained earnings flex got caught on the side of the mixing bowl when the mixer was raised. The flex stretched into a coil and the internal ground conductor pulled out of the terminal at one end. One of the phase conductors pulled and cut into the connector.
NM and NMC conductors are composed of two or more insulated conductors contained in a non-metallic sheath. The coating on NMC cable is non-conducting, flame-resistant and moisture-resistant. Unlike other cables commonly found in homes, they are permitted in damp environments, such as basements. There were originally two initial versions of armored cable. 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.
Today, and for a long time in the past, there is, and was, AC cable. You cannot apply uses of modern BX to vintage BX especially when replacing two-pin receptacles with three-pin ones. I can explain if you’re interested in what the problems were and the various early code developments that resulted if you’d like. Newly identified problems, new standards & tests, failed tests, former “faulty” requirement dropped – no need to continue or improve failed design meeting bad, no longer required standard. Still – you’d have to know if you were looking at conduit with 2 conductors or Cable, that’s why I asked the original poster. I simply put the “-X” to call out the word “Rome” before it as I did the “-X” to call out the word “Brand” before that.
Understanding Electrical Cable
Building wiring is the electrical wiring and associated devices such as switches, meters and light fittings used in buildings or other structures. BX is not a raceway, it is a cable there is no way you can pull the wire out unless the run is straight and maybe not more than 6′. BX by definition uses the armored jacket as the ground. Note Watson’s statement said “the term type AC”, keep track of that as he tries to change that to “Type AC cable'”. The NEC even points out that the life of rubber insulated conductors is limited. Honest BX, the stuff manufactured with rubber insulation on the conductors, is bad news. The only real way to see if you have problems with the stuff is to have it meggered.
It is very easy to transition between these two complementary wiring methods. Splices can be made in light fixture enclosures, wall boxes, or junction boxes.
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The hospital grade AC cable is the second variety of flexible armored cable developed by AFC called HCF. This HCF cable is designed for use not just in hospitals but also for other patient care areas.
Type EMT is suitable for branch circuits, feeders and services, and is used in sensitive areas such as elevator shafts and health-care facilities, and in some but not all classified areas. It is very widely used in commercial and industrial wiring, and for residential services. Compared to Rigid Metal Conduit , EMT is far less expensive and much easier to install. Segments can be marked with a fine-point felt-tipped pen and cut with a hacksaw, then reamed to remove sharp edges on the interior that could damage wire insulation. In commercial I usually see EMT in new construction and MC cable for retro work, simply because it is easier to fish. FMC is usually only used for short whips since it is hard to get wire stuffed through if any length is involved.
I still strongly suspect that the building being discussed has MC or AC cable, rather than flex. One would have to see the fittings, as well as inside the junction boxes, to tell. It looks neater, is easier to pull wire through, and you can pull any sort of wire you like. Under certain conditions, the conduit can also serve as the ground path. All of the existing wiring in the space goes UP from the box to the ceiling, then over to wherever and down, and all of that is BX wiring.
This makes insulation failure a rare occurrence and reduces the risk of accidental electrocution and arcing. The plastic used is resistant to moisture and microbes and is very durable. The plastic sheathing also has a very high melting point thus is heat and flame resistant. Splices are done in junction boxes, thus protected from the elements and pests. Plus all the wires needed for a circuit are right there together in one neat package. A cable consisting of wires contained in a flexible metal tubing, used chiefly in wiring buildings and in supplying electric power to equipment.
Amazon Com: Bx Cable
The use of removable carpet squares makes access to FCC easy, as one need only pull up one corner of the carpet square. In schools and residential occupancies, this could lead to easy access by children who pull up the carpet.
- It is acceptable to the latest version of the National Electrical Code .
- Quite handy, though, when you need to fish around various obstructions.
- Here is something I stated “my 1905 NEC does reference AC “, you then stated “I don’t believe the term type AC showed up until the 30s.”
- Armored or Metal Clad Cables used in exterior installations.
But what that protection is will depend on where the wires are installed and the environment of the installation. … Improbable History” to understand the … us any time from the early 1900s to yesterday to find BX cable. For all we know the bx was added to the K&T which was landed in the panel without a grounding conductor. Have rubber insulated conductors, rewiring is needed, the rubber insulation has dried out, is brittle, is cracked, has failed. 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”. I guess the “B” part was meant for the word “Brand” as in “Brand-X”.
If the architect, owner, or contractor had insisted on BX instead of NM cable, this repair would likely not have been necessary. There is also FMC, called by the slang of “Greenfield” that comes without conductors installed.
Why Is It Called Bx Cable?
Electrical Metallic Conduit is technically a tubing, not a type of conduit, although electricians talk about “putting the wire in conduit” and it is understood that they mean EMT. It is a thin-wall tubing, aluminum, stainless steel, or usually steel with a protective coating. Cable size is the gauge of individual wires within the cable, such accounting as 14, 12, 10 etc. – again, the bigger the number, the smaller the size. So, 10/3 would indicate the presence of 3 wires of 10-gauge within the cable. Ground wire, if present, is not indicated by this number, and is represented by the letter ‘G’. An electrical cable also has different types, color and application as its determining factors.
What Does Mc Mean In Electrical Terms?
InterNACHI inspectors should understand the basic distinctions between the different types of cable systems so that they can identify unsafe conditions. BX is as good as NM cable from a Magnetic Field standpoint but has the added benefit of shielding Electric Fields .
Armored cable was first listed with Underwriters Laboratories Inc. in 1899 for the Sprague Electric Co. of New York. It was originally called “Greenfield Flexible Steel-Armored Conductors,” after one of its inventors, what are retained earnings Harry Greenfield. During a Chelan Home Inspection I came across the use of what is often called BX cable. Change the date range, chart type and compare The Blackstone Group L.P. Commo against other companies.
A Little Bs On Bx Cables Armored Or Metal Clad Cables
Teck 90-HL armoured and jacketed cablesare suitable for exposed or concealed wiring in wet or drylocations where cables are subject to the risk of mechanicaldamage and chemical abuse. It can be used in ventilated ornon-ventilated ladder type cable tray or troughs and fordirect burial for Class I, Div 2 locations.
In some types of fixtures, both wires will be the same color. Romex is used for most lighting and outlet circuits in your home. EMT is also called “thin-wall” conduit becauseit is thin and lightweight, especially compared to RMC. EMTis bx cable definition rigid but can be bent with a simple tool called a conduitbender. EMT is installed with couplings and fittings thatare secured with setscrew or compression-typefasteners. Traditional Type MC cable is manufactured to ULStandard 1569.