By Dave Rongey Summary:
Electrical Wiring Question:
How do you know when to use 12-2 versus 12-3, 14-3 versus 14-2. I keep on getting confused on when to use 2 wire versus 3 wire.
Electrical Troubleshooting Question:
My question is, how do you know when to use 12-2 cable versus 12-3 cable, 14-3 cable versus 14-2 cable.
I keep on getting confused on when to use 2 wire versus 3 wire.
Thank You,Matt W.
Hi Matt - Great Electrical Repair Question!
2 and 3 wire cables can have several uses such as home run power feeds going back to the panel, branch feeds, single switching, 3-way switching, 4-way switching etc. It all depends on what you are wiring and what the electrical application will be.
Circuits Installed from the Electrical Panel
2-Wire Circuit
A 2-wire (black and white with the ground) cable will be used for one hot and one neutral or one circuit.
3-Wire Circuit
A 3-wire circuit (black, red, white and the ground) cable can be used for feeding two circuits that will share the neutral and ground wire.
Multi-Wire Configuration
The 2 circuit multi-wire configuration requires that the black and red hots be attached to a two-pole circuit breaker that has a tie-bar so that these two circuits are not fed from the same buss in the panel.
This will ensure that the neutral wire load will be balanced and not become overloaded under normal circumstances.
Voltage Readings
The voltage reading from black to red will be 240 volts because they are attached one to the two separate busses or phases, but the voltage reading from black to white/neutral or ground will be 120 volts and the same for the reading for the red wire to white/neutral or ground.
Be Careful and Be Safe, never work on energized circuits!
»You Can Avoid Costly Mistakes!«
Here is How to Do It:
Wire It Right with the help of my Illustrated Wiring Book Great for any Home Wiring Project.
Perfect for Homeowners, Students, Handyman, Handywomen, and Electricians Includes: Wiring GFCI Outlets Wiring Home Electric Circuits 120 Volt and 240 Volt Outlet Circuits Wiring Light Switches Wiring 3-Wire and 4-Wire Electric Range Wiring 3-Wire and 4-Wire Dryer Cord and Dryer Outlet How to Troubleshoot and Repair Electrical Wiring Wiring Methods for Upgrading Electrical Wiring NEC Codes for Home Electrical Wiring ....and much more.
The Safest Way to Test Electrical Devices and Identify Electric Wires!
The Non-Contact Electrical Tester
This is a testing tool that I have had in my personal electrical tool pouch for years, and is the first test tool I grab to help identify electrical wiring. It is a Non-contact tester that I use to easily Detect Voltage in Cables, Cords, Circuit Breakers, Lighting Fixtures, Switches, Outlets and Wires. Simply insert the end of the tester into an outlet, lamp socket, or hold the end of the tester against the wire you wish to test. Very handy and easy to use.
The Quickest Way to Check for Faulty Electrical Wiring!
The Plug-In Outlet Tester
This is the first tool I grab to troubleshoot a problem with outlet circuit wiring. This popular tester is also used by most inspectors to test for power and check the polarity of circuit wiring.
It detects probable improper wiring conditions in standard 110-125 VAC outlets
Provides 6 probable wiring conditions that are quick and easy to read for ultimate efficiency
Lights indicate if wiring is correct and indicator light chart is included
Tests standard 3-wire outlets
UL Listed
Light indicates if wiring is incorrect
Very handy and easy to use.
Strip Off Wire Insulation without Nicking and Damaging the Electric Wire!
The Wire Stripper and Wire Cutter
My absolute favorite wire stripping tool that I have had in my personal electrical tool pouch for years, and this is the tool I use to safely strip electrical wires.
This handy tool has multiple uses:
The wire gauges are shown on the side of the tool so you know which slot to use for stripping insulation.
The end of the tool can be used to grip and bend wire which is handy for attaching wire onto the screw terminals of switches and outlets..
The wire stripper will work on both solid and stranded wire. This tool is Very Handy and Easy to Use.
Splicing 220 Volt Wiring How to Splice 220 Volt Electrical Wiring: Considerations when splicing 220 volt cable wiring in order to make the splice safe, accessible and makes sure the circuit maintains integrity.
Upgrading Knob and Tube Electrical Wiring How can I replace knob and tube wiring? The Most Common Methods for Upgrading Knob and Tube Electrical Wiring, How to Upgrade Electrical Wiring for Light Fixtures and Switches.
How to Make an Electrical Cable Splice How to Splice Electrical Cables: Where the cables enter into the junction box will depend on the cable orientation, however I have found that it is best to enter at the same side in order to line up the conductors evenly for the splice.
Kitchen Light Fixture Wiring How to Connect the Wire When Replacing a Light Fixture that has Multiple Cables and Wires.
Understanding Electrical Wiring for Ceiling Light Fixtures Ceiling Light Fixture Electrical Wiring and Connections: Depending on the age of the home there may be one or more cables found in the ceiling junction box. These cables are used for distributing power to the light fixture, the wall switch, and may provide power to wall receptacle outlets as well.
Electrical Wiring for a Bath Light Fan Combo How do I wire the switches for my bath fan and light? How to Identify Electrical Wiring for Installing a Bath Fan Combo with a Light, Wiring Connections for a Bathroom Exhaust Fan.
Wiring a Time Switch for a Outside Light Fixture How can I replace a wall switch with a time switch for my outside lights? How to Wire a Timer Switch for Outdoor Lights, The Most Common Wire Colors and Connections for a Time Switch and How to Connect Them.
2 wire and 3 wire cables - 1794
Check Out What Others Are Sharing at Ask the Electrician: It is a very nice site with allot of useful information. Steve from Pittsburgh, Pennsylvania
Skill Level:
Intermediate to Advanced - Electrical Repairs and Circuit Wiring is Best Performed by a Licensed Electrical Contractor.
Tools Required:
Basic Electricians Pouch of Hand Tools, a Voltage Tester and a Multi Meter.
Estimated Time:
Depends on personal level experience, ability to work with tools, work with electrical wiring, and the available access to the project area. Precaution:
Identify the project circuit, turn it OFF and Tag it with a Note before working with the wiring.
Important:
Modifying existing electrical circuits or installing additional electrical wiring should be done according to local and national electrical codes with a permit and be inspected.
This is a testing tool that is a Non-contact tester that I use to easily Detect Voltage in Cables, Cords, Circuit Breakers, Lighting Fixtures, Switches, Outlets and Wires. Simply insert the end of the tester into an outlet, lamp socket, or hold the end of the tester against the wire you wish to test. Very handy and easy to use.
This is great to troubleshoot a problem with outlet circuit wiring, is also used by most inspectors to test for power and check the polarity of circuit wiring.
It detects probable improper wiring conditions in standard 110-125 VAC outlets
Provides 6 probable wiring conditions that are quick and easy to read for ultimate efficiency
Lights indicate if wiring is correct and indicator light chart is included
Tests standard 3-wire outlets UL Listed Light indicates if wiring is incorrect, Very handy and easy to use.
A wire stripping tool used to safely strip electrical wires.
This handy tool has multiple uses:
The wire gauges are shown on the side of the tool so you know which slot to use for stripping insulation.
The end of the tool can be used to grip and bend wire which is handy for attaching wire onto the screw terminals of switches and outlets.
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