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NMC electrical cable details (C) Carson Dunlop AssociatesElectrical Wire Stripping Tips for Homeowners

This article provides basic tips on how to strip the ends of electrical wires used in homes.

This website provides information about a variety of electrical hazards in buildings, with articles focused on the inspection, detection, and reporting of electrical hazards and on proper electrical repair methods for unsafe electrical conditions. Critique and content suggestions are invited. Credit is given to content editors and contributors.

Sketch at page top courtesy of Carson Dunlop Associates, a Toronto home inspection, education & report writing tool company [ carsondunlop.com ].

InspectAPedia tolerates no conflicts of interest. We have no relationship with advertisers, products, or services discussed at this website.

Electrical Wire End Stripping Tips

Open electrical panels are dangerous (C) Daniel Friedman

Watch Out:  Do not attempt to work on your electrical wiring, switches, or outlets unless you are properly trained and equipped to do so. Electrical components in a building can easily cause an electrical shock, burn, or even death. 

Even when a hot line switch is off, one terminal on the switch is still connected to the power source. Before doing any work on the switch, the power source must be turned off by set­ting a circuit breaker to OFF or removing a fuse

. See SAFETY for ELECTRICAL INSPECTORS and ELECTRICAL WIRING BOOKS & GUIDES

Different kinds of cables and electrical wire are commonly used by the homeowner or electrician when performing routine wiring tasks. 

These tasks are fairly easy to do but practice with the techniques involved always helps.  Before actually working with a type of wire or cable that is new to you, cut off a short piece and try stripping, joining, etc.  Experiment a bit to find out which of the tools you have available are easiest for you to use and which do the best job.  A little time spent in trial and error will make the job go faster.

How to Strip the Wire Ends for Plastic-Sheathed Electrical Cable

NMC electrical cable details (C) Carson Dunlop Associates

Permanent indoor installations are made by running lengths of wire between outlets and switches along or inside walls, floors, and ceilings. An electrical circuit always needs a hot and a neutral conductor plus a ground for safety.

When these individually insulated wires (black for hot, white or gray for neutral) are held together inside plastic or metal sheathing, the unit is called an electrical cable.

The most commonly used electrical cable for in­door wiring is the flat, white plastic type plastic-covered wire, or "Romex" (a trade name). Properly plastic-covered electrical wire is called "NMC" - non-metallic-sheathed cable. .

While there are many types and grades of non-metallic cable electrical wire, there are three basic kinds of interest to homeowners for most residential applications.

Sketch courtesy of Carson Dunlop Associates, a Toronto home inspection, education & report writing tool company [ carsondunlop.com ].


Aluminum NMC wire (C) Daniel Friedman

The type of electrical wire and its intended use is indicated by code letters printed on or embossed into the plastic wire jacket. (Our photo shows an obsolete aluminum conductor NM wire made by Primus).

How to Remove the Plastic Sheathing from Plastic-Sheathed Electrical Wire

Stripped aluminum wire (C) Daniel Friedman

Above: photo of stripped ends of aluminum electrical wiring.

See ALUMINUM WIRING HAZARDS & REPAIRS - home

How to Remove the Metal Sheathing from Armored Cable ("BX") Electrical Wires or from Flexible Conduit

Armored cable or metallic-sheathed electrical cable has been in use since 1896 (in the U.K.) and in its most basic form contains two electrical conductors (black-hot and white-neutral) each individually insulated and both usually wrapped with a spiral of paper which is in turn enclosed in a flexible metallic sheathing such as shown in our abandoned-wire photograph below.

How to cut armored cable (AC) or BX flexible conduit or metal-clad (MC) Cables - NH Firebear (C) InspectApedia

Don't leave a cut like the BX FMC shown above. Do use a plastic bushing insert to protect the conductors from damage.

Hacksaw method for stripping armored cable (AC), BX cable, metallic cable (MC) or flexible metal conduit

Below: a red-head bushing intended to protect the conductors from damage by the sharp edges of the cut metal BX sheath.

How to cut armored cable (AC) or BX flexible conduit or metal-clad (MC) Cables - NH Firebear (C) InspectApedia

More about identifying and actual wiring methods when using flexible metal conduit / armored cable - BX is given in detail

at BX WIRING GUIDE where we illustrate using the special BX conduit cutting tool.

at ARMORED CABLE or BX WIRE IDENTIFICATION

 

How Much Insulation Should Be Removed From the Actual Wires Themselves?

NMB_3-wire_with_Ground_Stripped (C) Daniel Friedman

How much insulation should be stripped off of the individual wire conductors once the wire jacket has been removed? As my friend and mentor Mark Cramer, Tampa home inspector and educator, says, "Well ... it depends." It depends on the device to which the wire is to be connected.

We want to remove enough insulation to assure good contact area between the wire and the connecting device, but not too much.

Black wire Red wire White wire

Watch out: not all devices use the same conductor insulation strip-back amount. In general you will need to remove more insulation to wrap a wire around a binding head screw connector than to push the wire into a push-in type connector. Above I've removed the jacket from 14-3 NMB electrical wire.

The ground wire is already bare but I'll need to remove insulation from the black, red, and white conductors before they can be connected to a device or to a splice.

Excerpting from HOW to CONNECT WIRES to a RECEPTACLE or SWITCH

Strip gauge on an electrical receptacle shows how much insulation to remove when back-wiring the device. (C) Daniel Friedman

Above I'm showing the wire strip-back gauge area marked on the back of a 15A electrical receptacle. This gauge shows the amount of insulation that should be removed presumably for either of the types of connectors provided on this particular device.

For the device shown above we are to remove from 1/2" to 5/8" of insulation, or about 16mm.

Below is a rather shorter wire stripping gauge telling us that for the device where this gauge appears - in this case a screw-clamp type wire connector, somewhat less insulation is to be removed. For the device shown below we are to remove 9mm of insulation - about 0.35" - quite a bit less insulation than for the device above.

Strip gauge dimensions on a pressure plate screw clamp connector of an electrical receptacle (C) Daniel Friedman

Watch out: don't strip off too little insulation or the wire will not make a safe, reliable electrical connection: either the wire won't push far enough into the screw-clamp connector or the insulation may prevent the binding head screw from pinching the wire - it'll pinch onto the insulation instead, making a loose, poor electrical contact.

And don't strip off too much wire insulation or the extra length of bare wire may cause a short circuit when you push the device back into its electrical box. That's more than embarrassing, it's dangerous. Trust me.

Most light switches and receptacles include this indicator that tells you how much insulation the manufacturer recommends stripping off when wiring this device.

Typically we're removing from 1/2" to about 5/8" of insulation, taking care not to damage or notch the wire. It makes sense, then, to actually look at these instructions given by the manufacturer, as not all strip gauges show the same strip-back quantity.


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