Customers may only want to replace the knob and tube and leave the BX wiring. 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. It is possible to cut and rip the armor without a BX cutting tool. You can cut the outer armor with a hacksaw, assisted with a strong pair of wire snippers or pliers. Wires within the armor may display degradation of their rubber insulation.
- These may be a bit on the pricier side, but will save you time and money trying to find an alternative.
- If there is a metal clamp or securing bar of some kind, you should be able to connect a grounding pigtail to that for each MC/BX, then use a wire nut to join those and any switch/outlet ground pigtails.
- The individual conductors in the cable are metallic with about 65-percent copper.
- 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.
- Assuming its bend radius is observed carefully, an NEC-compliant install of BX is unlikely to be damaged during normal use.
It would be best to start by cutting across the armor, excluding the spiral. It isn’t necessary at all to cut through the armor completely. 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. Great from protecting the cable from rodents, boxes falling on them and light foot trafficked areas. In some cases, it can even be buried in dry or covered climates. There is also FMC, called by the slang of “Greenfield” that comes without conductors installed.
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The National Electrical Code prohibits use of BX ( technically named Armored Cable/AC ) in wet locations. 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 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. Most customers who are replacing their knob and tube wiring for insulation will leave the bx wiring in place. We often joke that we are saving some work for later, that we will be going back through all these homes again in 10 years to replace the BX wiring. When customers have all three styles of wiring, we normally recommend our whole-house wiring evaluation/mapping.
They also have smooth sheathing that makes them easier for pulling through holes. There is even an added coat that creates slippery sheathing. 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. The use of devices that might damage cables, including overdriven staples and bent nails, isn’t permitted. Put a BX connector on the end of the cut armor and then tighten the screw for you to secure the armor.
Metal Clad MC Lighting Cable AL Conductor 2/3 1/3 BX Cable Armored Cable UL1569 No.E 466697 600V
An electric circuit is made up of several wires and cables. If you want a continuous flow of electric current, you need to utilize electrical connectors. Bx wire have plugs and jacks that link to one another to form either a permanent or temporary connection. So when you want to break the circuit, you can disconnect them with proper tools. One advantage of bxables is that they help in reducing the amount of time, effort, and labor required to manufacture, assemble and install electrical equipment. 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.
I’ve been conducting professional home inspections since 2002. I’m a licensed Home Inspector, Certified Professional Inspector , Certified Master Inspector , and FHA 203k Consultant. I started HomeInspectionInsider.com to help people better understand the home inspection process and answer questions about homeownership and home maintenance. Since then, Romex has been in production, especially by companies that took over from where ‘Rome Cable Corp’ left. For instance, if you want to strip insulation from a 12-gauge wire, you should select the hole that is labeled ’12’.
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If you expect to be doing a lot of cutting, you may wish to invest in a special BX cutter, such as the Roto-Split. 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 old BX wiring is in good condition and can carry today’s higher power demands, there is usually no reason to replace it.
Where do you use BX wire?
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.
Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy. Lee has over two decades of hands-on experience remodeling, fixing, and improving homes, and has been providing home improvement advice for over 13 years.
We test your building or property to find harmful pollutants. This is why I always use BX on my own jobs and recommend it on any project in which I am consulting. See the earlier blog on knob-and-tube common Residential Wiring Errors here. 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, and good EF shielding. NM cable is flexible, heat & fire resistant, easy to install, and relatively inexpensive.
Is BX wire safe?
The actual name for it is “Armored Cable” or AC, but many people call it by its original trade name “Greenfield” or just BX. Modern BX wiring, properly installed, is safe. It is acceptable to the latest version of the National Electrical Code (2017 NEC Article 320).