Understanding the Importance of Electrical Codes for Home Electrical Services
Primary Cause of Failures:
NEC 110.3
Written Electrical Correction - All locations
Failure to read the manufacturer's instructions.
NEC 110.3
Electrical equipment Equipment Listing and Labeling All electrical equipment, including luminaires, devices and appliances used as part of or in connection with an electrical installation shall be listed and labeled by a Nationally Recognized Testing Laboratory (NRTL) as having been tested and found suitable for a specific purpose.
Code Adoption Information:
The codes shown are examples only and may not be current or accurate for your application or jurisdiction. Contact your local building authority for complete information.
NATIONAL ELECTRICAL CODES
NEC 110-3 and 110-14 Anti-Oxidant Compound shall be used on all aluminum conductor terminations.
NEC 110-26 The Depth of Working Space in the direction of access to live parts, when the voltage to ground does not exceed 150 volts, shall be a minimum of 3 feet. The minimum width of working space in front of electrical equipment shall be the width of the equipment or 30 inches, whichever is greater. This workspace shall be clear and extend from the floor to a height of 6 1/2 feet, and shall not be used for storage. All workspaces shall be provided with illumination.
NEC 230-8 and 230-54 Service Entrance Conduits shall be rain tight, arranged to drain, and sealed to prevent moisture condensation. Conductor Sizes for 120/240 Volt Single-Phase Dwelling Services
NEC 310-15 Copper Aluminum Service Rating ..............4 AWG......2 AWG ..100 amps ..............1 AWG..........2/0.... 150 amps .................2/0............ 4/0..... 200 amps Consult the conductor insulation type to determine the exact service rating.
NEC 230.54 Electrical Services - Service entrance raceways shall be rain-tight and arranged to drain.
NEC 230.70 Electrical Services - The service disconnecting means shall be installed at a readily accessible location either outside a building or structure or inside nearest the point of entrance of the service entrance conductors.
NEC 240-3 The rating of the fuse or circuit breaker generally determines the minimum size of the circuit conductor, per the following table:
Minimum Wire Size Fuse or Circuit
Breaker Size Copper / Aluminum 15 amp ..........14... n/a 20 amp ..........12... n/a 30 amp ..........10.... 8 40 amp ...........8.... 6 50 amp ...........6.... 4
Note: Conductors that supply motors, air conditioning units, and other special equipment may have overcurrent protection that exceeds the general limitations in the above chart.
NEC 240-24 Electrical Panels shall be readily accessible and shall not be located in bathrooms or in the vicinity of easily ignitable materials such as in clothes closets.
NEC 300.4 Electrical Services Conduit raceways "Where raceways containing ungrounded conductors No. 4 or larger enter a cabinet, box, or enclosure, the conductors shall be protected by a bushing providing a smoothly rounded insulating surface.
NEC 300-5 Underground Service laterals shall have their location identified by a warning ribbon that is placed in the trench at least 12 inches above the underground installation.
NEC 300.5 Underground Wiring conduits and raceways "Direct buried cable or conduit or other raceways shall meet the following minimum cover requirements:
Direct Burial Cable Rigid or Intermediate Metal Conduit Non Metallic Raceway (PVC)
24 inches 6 inches 18".
Residential branch circuits rated 20 amps or less at 120 volts or less and with GFCI protection at their source are allowed a minimum cover of 12".
NOTE: This table does not apply to underground wiring for outdoor pools, spas, or hot tubs - see NEC Article 680.
NEC 300.7 Electrical Services Wire Conductors Portions of raceways or sleeves subject to different temperatures (i.e. passing from the interior to the exterior of a building) shall be sealed with an approved material to prevent condensation from entering equipment.
NEC 300.9 Electrical Services Conduit raceways The interior of raceways installed in wet locations above grade shall be considered wet locations.
NEC 310-15 Electrical Services wire conductor sizes "CONDUCTOR SIZES FOR 120/240 VOLT 3-WIRE, SINGLE-PHASE, DWELLING SERVICES AND FEEDERS Copper -- Aluminum -- Service Rating 4 AWG......2 AWG ......100 amps 1 AWG......2/0 ............150 amps 2/0............4/0 ............200 amps
400 kcmil..600 kcmil.....400 amps
NEC 384-13 All Circuit Overcurrent Devices shall be legibly identified as to purpose or use on a directory located on the face or inside of the electrical panel doors.
NEC 370-17 Raceways Containing Ungrounded Conductors No. 4 or larger enter a cabinet, box, or enclosure, the conductors shall be protected by a conduit bushing providing a smoothly rounded insulating surface.
Residential Electrical Code Examples for Services
IRC Codes Home Electrical Service
1.A minimum of 100 Amp 3-wire service for a single-family dwelling unit. NEC 230.79
2.Only one service per dwelling, except for multiple occupancy buildings. NEC 230.2
3.Service disconnecting means shall be located at the point of entrance of the service conductors. 2003 IRC E3501.6.2
Electrical Disconnects
1.Exterior air units must have a disconnect within sight. NEC 440.14
2.Minimum disconnect rating for one circuit is 15 amps, for two circuits is 30 amps and for all others it is 60 amps. (detached garages with more than two circuits must have 60 amp wire) NEC 230.79
3.Electric water heaters shall have a disconnecting means within sight of the appliance or have a circuit breaker capable of being locked in the open position. NEC 430.III.
General Information
Working space around electrical equipment shall be minimum: 30" wide and 36" deep and 6'-6" high. If the equipment is higher than 6'-6", the minimum height shall be to the top of the equipment. It also must be illuminated. 2003 IRC E3503
Always contact your local building authority for complete and up to date code information.
»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.
Questions about Electrical Codes for Electrical Service Panels
Questions about Residential Electrical Wiring Codes for Main Services
Question from Willie, a Handyman in Newark, New Jersey
How is a Sub Panel Wired to a Main Service Panel?
I am adding a sub panel to my main panel in the basement. My problem is the main panel has two wire conductors with no ground, The neutral and ground bar are side by side in my main panel. The neutral wire runs through the neutral and touches the ground, But the sub panel I installed has a ground and neutral bar. So how can I connect a two wire black and neutral wire to a black, red, white, and ground in my sub panel?
Dave’s Answer: Neutral and Ground Separation in a Sub Panel
The neutral bar is bonded to the ground only in the main panel. However, in a sub panel the neutral bar is separated and insulated from the ground and a separate neutral wire is required as part of the circuit feeding the sub panel. Additionally, a separate ground wire is required for the ground bar, which is bonded to the enclosure of the panel.
Question from Rob, a Handyman in Decatur Island, Washington
Installing a 200 amp Service Line
I am working on installing a 200 amp service line from a pad transformer (OPALCO-Orcas Power and Light) and meter base with a main disconnect out to my cabin which is approximately 250′ away, and into an Eaton 200 amp panel inside my cabin. I need to know the type of service wire I need (how many exactly, 3 or 4?) to put in the conduit in the trench and also the depth of the line, 18 or 24″ deep? I was told I need 4-0 wire (2 leads and a neutral) but I’ve also seen several diagrams with an added ground wire connecting the meter base and the panel, so that would mean 4 wires in the pipe. I was going to use 2.5″ Schedule 40 in the ditch and switch to 80 when it comes up and into the cabin. I was also planning to set two ground rods at the meter base (using 6 or 8 gauge copper wire?) and then another set of ground rods at the cabin for the panel itself. Would this work?
PLEASE NOTE:
To avoid redundancy, answers to most of these questions are available here on the website, or by obtaining a copy of the Home Electrical Wiring book.
IMPORTANT:
Electrical Panel Work of any kind should be done by a Licensed Electrical Contractor.
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.
Electrical Code and Swimming Pool Light Fixtures GFCI Ground Fault Protection for Swimming Pool Lights: NEC Article 680-20, As described in this electrical question, anyone who enters the pool with this light on is in Danger of Potential Electrical Shock!
Electrical Code for Garage GFI Outlets and Receptacles How to Plan and Install Electrical Wiring for Garage Outlets and Lighting Circuits: Electrical Codes about GFCI protection for 15A and 20A, 125V receptacles in garages.
Electric Well Pump Circuits Can I power my shed with 120volt from the 240volt well circuit? Installing a 240volt 3wire Circuit for a Well Pump Panel, Dedicated Circuit for Well Pumps.
Wiring a 220 Volt Air Compressor How to Install a 220 Volt Air Compressor Circuit: Electrical Circuit Requirements, 220 Volt Single Phase and 220 Volt 3 Phase
Wiring a Switch and Outlet Combination How to Wire a Combo Switch Outlet: These switch outlets are pretty handy and once the wiring designations are understood the wiring can be a snap.
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.
Older Home Electrical Wiring Problems Working with Older Home Electrical Wiring: What To Do When an Inspection Reveals Older Home Electrical Wiring Problems.
Check Out What Others Are Sharing at Ask the Electrician: Looks like a great resource! I am bookmarking your site. Jim from Santa Rosa, California
Electrical Wiring Codes
Electrical Project Skill Level:
Intermediate to Advanced - Best performed by a Certified Electrician or Licensed Electrical Contractor.
Electrical Tools Required:
Basic Electricians Pouch of Hand Tools, Battery Tools, Electric Power Tools, Electrical Meters and Voltage Testers.
Estimated Time:
Depends on personal level of working capabilities and electrical experience, electrical certification or contractors license, ability to work with tools, install electrical circuit wiring, and the available access to the project area. Electrical Safety:
Identify the electric panel circuits found in the project area, turn them OFF and Tag them with a Note before working with the electrical wiring.
Electrical Wiring Parts and Materials:
Electrical parts and materials for all electrical projects should be approved for the specific project and compliant with local and national electrical codes.
Electrical Codes and Inspections:
Installing additional electrical circuits or 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.
I think your site offers the the clearest and best electrical information for homeowners I have ever seen on the net.You have given me confidence to do my own projects which I never had before. THANK YOU! Paul, from Foxboro, Massachusetts
I wish I found this site earlier, it is by far the best electrical related resource I have found on the web. George, from Scranton, Pennsylvania
I love this site for an office worker that does not know anything about electric wiring. Bill, from New York City, New York
This site is so much better than the 3 books I just bought, I wish I came here first. Collin, from Grand Rapids, Michigan
Thank you for answering my question.
I was able to get this done. This site is perfect. I am glad I found it. Please keep it going. Mike, from Chicago, Illinois
