It has a cloth insulation which can break down to expose bare copper. This is particularly an issue in lights where heat from light bulbs has baked the wiring for years. We get a lot of questions from customers who are looking to replace their BX wiring. We thought it would be helpful to have all the questions and answers in one place. If there are any questions you would like addressed not on this list, please let us know.
- Unless the specifics of the job or the electrical code demand that you use BX cable, your wiring project will go faster with NM, plastic-sheathed wiring.
- This matters because MC cable can be used outdoors in certain circumstances, but BX/AC never can be, contrary to many online sources.
- To give a free estimate, we will shut down ALL the visible BX wiring in the electrical panel, walk through the home together, and identify all the outlets, lights, and switches that are now OFF.
- These same properties might make BX beneficial for use by audiophiles, as well.
- Three prong outlets cannot be installed on BX wiring, unless a GFCI outlet is used.
It is the opposite of NM cables that you can install in enclosed environments. It cannot be buried in grade or masonry without protection. The method of the time was to put this wire in watertight metal conduit whenever it needed to pass through the ground or masonry. IF YOU HAVE BX OR AC WIRE BURIED IN OLD METAL CONDUIT – IT LIKELY NEEDS REPLACEMENT – SINCE THE METAL CONDUIT HAS LIKELY RUSTED OUT MANY YEARS AGO! If some or all of these connectors are loose, the ground connection get’s worse and worse as you go down the line. We see this a lot, where we are measure voltages and have say 120 volts between hot and neutral, but only 60 volts between hot and ground.
Microwave Breaker Size: Wire & Outlet for Microwave Ovens
BX is contrasted with a newer cable, NM, which stands for “non-metallic.” Instead of the metal sheathing, NM has a slick vinyl covering that is easy to rip and pull through holes in studs. Wiring in locations that are subject to “physical damage” will need protection. But what that protection is will depend on where the wires are installed and the environment of the installation. Romex wires are easier to handle since they are lighter compared to metallic sheathed wires. If you’re a do-it-yourself electrician, you’ll find it easier working with Romex and NM brand cables than BX cables. However, some specific electrical codes or tasks require BX cables.
Above is a great example of both BX wiring and knob-and-tube wiring working together. Notice the two black wires leaving the same junction box as the BX wires . Widespread production and use of BX cable began in the 1920s when BX was promoted as being a modern, safe, fireproof improvement over older cloth-sheathed wiring. Running electric cable from the electric service panel to devices like outlets or switches is at the heart of any electric project. Your choice of electric cable is not only based on the project requirements but on your skill level and experience.
To give a free estimate, we will shut down ALL the visible BX wiring in the electrical panel, walk through the home together, and identify all the outlets, lights, and switches that are now OFF. Early forms of BX can still be found by homeowners renovating their homes. It is not certain how the term “BX” came to represent metal-armored cable, but it may have something to do with the product first being produced in the Bronx borough of New York. 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.
As home inspectors we see a lot of wiring in locations that need protection. Many common areas I find unprotected wiring are in closets and cabinets. The unique downsides of BX are that it cannot be used in wet, damp, or exterior locations, and obviously it bx wiring 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 . I swapped an old light switch to a Z-Wave one that didn’t like being in a metal box.
What is BX wiring?
What BX Cable and Wire Is. Going under alternative names such as metallic sheathed cable, type AC, MC, Greenfield, or armored cable, BX cable is a collection of plastic-coated insulated wires (typically 14- or 12-gauge), bundled together and protected by a ribbon-like metal sheathing.