An example of this is the use of the grounding conductor (and therefore the armor itself) as a neutral conductor rather than a ground — an inexpressibly dangerous mistake. McCurdy says that the insulation, wraps, anti-short bushings, bonding wire, and galvanizing process of the early BX cable have all been improved and are as safe today as other approved cables. The wire is protected by romex vs bx 2 layers of insulation, with each individual conductor being insulated and the entire bundle also being insulated. This makes insulation failure a rare occurrence and reduces the risk of accidental electrocution and arcing.

The home was recently framed and paneled, but the electrical was not yet installed. For those prioritizing long-term safety and robustness, especially in commercial or industrial settings, BX cable is worth the extra investment. For instance, if you want to strip insulation from a 12-gauge wire, you should select the hole that is labeled ’12’. If you want to connect any devices, you must first strip the wire insulation from copper wire using manual wire strippers. The National Electrical Code puts the required minimum amount of cable that should extend past the junction box. However, not all these cables are available for application in all circumstances.

You calculate its properties as a conductor by stretching it out to its uncoiled (and much greater) full length, because the interlocking edges aren’t considered a strong enough electrical link. One added benefit of NM cable over knob and tube is that knob and tube emits fairly high levels of low frequency alternating current magnetic fields, due to the separation of the hot and neutral conductors. The magnetic field strength around knob and tube carries a good distance from the wires and is proportional to the distance between the hot and neutral conductors. 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. Cable manufacturer Southwire claims BX can reduce installation costs by 50%, as compared to conduit and wire.

One final distinction is that MC cables don’t have a limited number of conductors they can contain, while AC cable can contain no more than four insulated conductors. What MC and BX have in common is their basic armored structure, which means that its individual conductors are better protected than NM and similar cable. Both are sometimes simpler to install that wire in conduits, which reduces the cost. BX cable can, by some estimates, be 35-40% more expensive than NM (via Healthy Building Science), yet still be cheaper to install overall. BX cable comprises plastic-coated insulated wires of about 12- or 14-gauge rolled up together and protected using a ribbon-like metal sheathing.

  • NM cable is flexible, heat & fire resistant, easy to install, and relatively inexpensive.
  • Whereas Romex is easy to both install and cut or puncture, armored cables are more difficult to use, specifically because they provide their wires more protection.
  • The unique downsides of BX are that it cannot be used in wet, damp, or exterior locations, and obviously it cannot therefore be direct-buried or used as aerial cable.
  • For those prioritizing long-term safety and robustness, especially in commercial or industrial settings, BX cable is worth the extra investment.
  • Modern BX cable has a plastic-covered ground wire, while Romex has a bare copper ground wire.

All Access

At its core, BX cable is made up of several insulated wires and one ground wire which may or may not be insulated and held together with strips of paper wrapped around them in a spiral fashion. I want to install fiber-optic cable in the walls to future-proof our home. Fiber-optic is much faster, can handle more information, and ensures less latency than either wireless or ethernet cable. Years ago, we went “wireless-free” by hard-wiring all stationary electronics and communication devices in our home and office.

  • BX cable can, by some estimates, be 35-40% more expensive than NM (via Healthy Building Science), yet still be cheaper to install overall.
  • BX cable is armored, and that obviously improves its resistance to puncture by nails and screws.
  • The city only started allowing Romex use a few years back and I think I’ve done 1 job with it.
  • Less EMI translates into a better function for all electronic devices, reduces the electric field size, and causes a minimal EMI coupled to the indoor E and B fields.

Finally, you can add cable supports such as brackets, clamps, and staples.

NM (Non-Metallic) Cables

BX wire has a metallic protective covering used mainly in areas where the wire is outside a finished wall and acts as an electrical conduit. In addition, both Romex and BX have plastic-coated insulated copper wires. Modern BX cable has a plastic-covered ground wire, while Romex has a bare copper ground wire. BX is as good as NM cable from a Magnetic Field (MF) standpoint but has the added benefit of shielding Electric Fields (EF). The metal sheathing absorbs the electric fields emitted by the wires and shunts it to ground.

The History and Development of BX Cable

Your choice of cable depends on the requirements of your project and your skill level and experience. The flexible metal sheathing is easy to install, about as easy as NM cable. It resists puncture by nails and screws, and, as I will describe later, is more resistant to being chewed through by rodents and other pests than NM cable and knob and tube. Southwire’s MCAP product, a metal-clad cable which uses its armor for grounding, is $238 for the same specs at Home Depot. Southwire offers a calculator to demonstrate the supposed labor savings that justify the simpler installation of MCAP versus standard MC wire, which involves one fewer termination per electrical box. Assuming a home uses 10 circuits (via D&F Liquidators) and 10 outlets, plus another five terminations for switches and light fixtures (via REthority), the calculator estimates $625 in savings for all 150 termination points.

Romex vs AC (BX)

The cable jackets are color-coded to permit identifying the cable sizes quickly—black jacket for #6 and # 8 AWG, orange jacket for # 10 AWG, yellow jacket and red jacket for # 12 AWG, and white jacket for # 14 AWG. NMD90 Red sheathing is only used for wiring baseboard or convection heaters. If you are thinking of running wiring in your home, you will have several options for the type of wire to use and how to protect it; however, two of the most common and popular choices are NM cable and armored cable. The individual conductors in the cable are metallic with about 65-percent copper.

The unique downsides of BX are that it cannot be used in wet, damp, or exterior locations, and obviously it cannot therefore be direct-buried or used as aerial cable. It turns out there are versions of MC that share all of the potential major pros of BX and none of the cons (via North Central Washington Home Inspections). Less EMI translates into a better function for all electronic devices, reduces the electric field size, and causes a minimal EMI coupled to the indoor E and B fields. Yesterday, I mentioned that my dream is to build our family’s home someday and install BX cable and fiber-optic light pipe into the walls.

NM cables can be effortlessly cut, stripped, and pulled through stud holes, making them a convenient option. BX wires are a type of metal-clad electrical cable that has been a popular choice for homeowners in the past due to its durability and added protection. Running electric cables from the electrical panel to devices like outlets or switches is crucial to any electrical project.

After ripping, you can cut the remaining sheathing using scissors, a wire stripper, or a utility knife. Or click the button below, tell us a little about your project and let our environmental consultants help you create a healthier building. NM cable is flexible, heat & fire resistant, easy to install, and relatively inexpensive. Although NM cables are better suited for general wiring than BX, there are certain situations where some cables cannot benefit from the wall enclosure to protect them resulting in partial or total exposure to potential hazards. In such situations, the Bx can offer one of the best available solutions.

BX is among the earliest electrical cables designed for commercial and residential uses in the early 20th century. We also offer other types of electrical solutions including electrical panel replacement, whole-house generator configuration, ceiling fan replacement, safety inspections, and lighting installation. By partnering with our team, you can rest assured that we will thoroughly inspect the electrical wiring in your house, identify the materials used, and perform any necessary installation or replacement services. Similar to MC cables, BX wires offer various pros and cons due to their shared characteristics and usage restrictions compared to non-metallic (NM) cables like Romex.