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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.

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Electrical Junction Box Size and Wire Capacity
[ad#block]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.

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.

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

• 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.
• 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.
• Home Wiring
• Basic Home Wiring Diagrams with Pictures

The following may also be helpful for you:

Dave's Companion Guide to Home Electrical Wiring:

 » You Can Avoid Costly Mistakes! « Here's How to Do It: 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
How to Troubleshoot and Repair Electrical Wiring
Wiring Methods for Upgrading Electrical Wiring
NEC Codes for Home Electrical Wiring
....and much more.

 More articles about Electrical Parts, Electrical Wiring, Junction Box, National Electrical Code and Home Electrical Wiring: « Previous Next » Panel Wiring for a Home Theater Timers and Light Switch Wiring

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

4 Responses to “How Many Electrical Wires In a Junction Box”
1. Bruce says:

I am wiring a 47 foot trailer, first time I am an industrial electrician. This trailer will have 12 bunk beds in the back with receptacles. There are two showers in the front kitchen laundry and TV area. I just installed a PT AC unit 220 30 amp, 80 gal hot water heater 220 20 amps I think, washer and dryer, electric range, exhaust fans for the bathrooms, microwave, refrigerator, maybe two ceiling fans. What size panel box do you think? Also looking at a generator that can handle the load. This unit will be used to house workers, working in shifts at natural disaster areas maybe 2 to 6 months at a time.

2. Dave Rongey says:

Hi Bruce,
Go on over to the Electrical Load Calculator where you can put in your information to determine the estimated load. This will help you to size the electrical panel.
I hope this helps,
Dave

3. Zoran says:

How many #12 wires am I allowed by the code to splice in a 6x6x4 pull box or 8x8x4 pull box?

4. Dave Rongey says:

Hi Zoran – Great Question,
The number of wires that can be spliced in a junction box, pull can or pull box will depend on a few factors, such as how many of the wires will be ground wires, the type of conduit fittings or cable connectors etc.
Please refer to the following page for more specific information:
Electrical Code for Splicing Wires in Junction Boxes.
I hope this helps,
Dave