How Many Electrical Wires In a Junction Box

How to Wire a Junction Box: Selecting a Junction Box for Electrical Wiring, The Basics of Electrical Junction Boxes, The number of wires that are allowed in a Junction Box.

Electrical Junction Box Size and Wire Capacity
Electrical Question: Can I connect all the white wires and black wires into large wire nuts in the junction box as long as the number of wires in the box is less than 14?

• I wired a circuit from the power box to three wall receptacles.
• I then ran wiring to three closet lights with single pole switches, and to three lights in a hallway operated by two three-way switches on each end of the hall.
• All of these switched lights are joined at one junction box accessible in the hallway.
• I connected all the white wires together and black wires together (and ground wires)in the junction box.
• The box is a three gang box with 14AWG and 12 AWG wire capacity marked in the box.
• Electrical Questions:
  • When using large button wire connectors, is connecting all the white and black wires in the one junction box acceptable as long as the number of wires in the box is less than 14?
  • Is this method acceptable?
• The above circuit works well and checks out OK with a LED reading of one red, and two orange LED lights on Sperry Tester.

Background: Robert , a Homeowner from Kennesaw, Georgia.

Dave’s Reply:
Thanks for your electrical wiring question Robert.

Electrical Junction Boxes and Enclosures

Application: Wiring a Junction Box.
Skill Level: Beginner to Intermediate – Best performed by a Licensed Electrical Contractor.
Tools Required: Basic Electricians Pouch Hand Tools and a Voltage Tester.
Estimated Time: Depends on personal level experience, ability to work with tools and the number of outlets that will be added and the access to the location for the new outlets.
Precaution: Identify the existing outlet circuit, turn it OFF and Tag it with a Note before working with the wiring.
Notice: Installing electrical wiring for additional outlets should be done according to local and national electrical codes with a permit and be inspected.

Selecting a Junction Box for Electrical Wiring

Electrical junction boxes are selected for the specific type of electrical wiring work that is being done. As described below, there are several types of junction boxes and electrical work boxes that are available. The more specific the task is the easier it is to identify which type of junction box can be used.

Types of Electrical Junction Boxes

• The Most Common Style of Junction Boxes and Enclosures
  
  • Gutter splice box.
  • Pull box, for pulling large wire and creating a loop.
  • Fixture Box, typically 3 inch or 4 inch round.
  • Switch or receptacle box, typically 1 gang to 6 gang

• Material Types
  
  • Metal, steel or aluminum
  • Plastic
  • Fiberglass

• Application Types
  
  • Indoor – NEMA 1
  • Outdoor – NEMA 3R
  • Special Purpose, such as Explosion Proof

• Finish Types
  
  • Surface Mount
  • Flush Mount
  • Cut-In, Flush Mount

• Mounting Types
  
  • Side Nail
  • Face Nail
  • Bracket
  • Cut-In
  • Direct mount through the box or enclosure

• Types of Electrical Boxes
  • Junction Box
  • Outlet Receptacle Box
  • Light Fixture Box
  • Light Switch Box
• The number of wires that are allowed in a Junction Box will depend on:
  • The size of the junction box.
  • The number of insulated wires.
  • The number of ground wires.
  • The size or gauge of the wires.
  • The number of cable connectors installed into the junction box.
• NEC Electrical Code: As stated in the NEC National Electrical Code, the total number of wires that can be allowed in a junction box will depend in the specific box that is installed, and the specifications for that box, which translates to the total number of cubic inches that are reserved for the electrical wires.

More about Electrical Junction Boxes

Electrical Wiring Codes

Home Electrical Codes

Electrical Code Directory covering AFCI circuit, electrical-boxes, electrical-circuit, electrical-code-outlets, electrical GFCI, electrical-grounding, electrical-project, electrical-services, electrical-underground, electrical-wiring, electrical-wiring-code, lighting-codes and smoke-detectors.

Electrical Code for How Many Wires in Junction Boxes

Home Electrical Junction Boxes

• Electrical Junction Boxes for Home Wiring

• A description of electrical junction boxes and what they are used for. Home electrical wiring is the process of installing electrical wire to a location that will serve electrical devices or an appliance. One very important component is the box where the wire will be installed.
• The type and size of the home wiring electrical boxes will depend upon the circuit size, application and its location.

Circuit Wiring

• Electrical Circuit Wiring

• The most common 120 volt and 240 volt house wiring circuits and the circuit breakers that are installed identifying the types and amperage sizes used in most homes.

• Electrical Wire for the Home
• For more information about Home Wiring

Home Wiring

• Home Wiring
• Basic Home Wiring Diagrams with Pictures

The following may also be helpful for you:

Dave's Guide to Home Electrical Wiring: » You Can Avoid Costly Mistakes! « Wire It Right with the help of my Illustrated Wiring Book Great for any Home Wiring Project. Complete Guide to Home Electrical Wiring Perfect for Homeowners, Students, Handyman, Handy Women, 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 Troubleshoot and Repair Electrical Wiring Wiring Methods for Upgrading Electrical Wiring NEC Codes for Home Electrical Wiring ....and much more. Learn more about Home Electrical Wiring with my Online Video Course: Basic Home Electrical Wiring by Example

Be Careful and Be Safe - Never Work on Energized Circuits!
Consult your Local Building Department about Permits and Inspections for all Electric Wiring Projects.

Electrical Tips to Help You Wire it Right 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.

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