Service Panel (pages 26 to 33)
• Maintain a minimum 30' x 36" of clearance in front of the service panel.
• Ground all 120-volt and 240-volt circuits.
• Match the amperage rating of the circuit when replacing fuses.
• Locate service panels and subpanels a maximum of 79" above floor level.
• Use handle-tie breakers for 240-volt loads (line to line).
• Close all unused service panel openings.
• Label each fuse and breaker clearly on the panel.
Electrical Boxes (pages 36 to 41)
• Use boxes that are large enough to accommodate the number of wires entering the box.
• Locate all receptacle boxes 12" above the finished floor (standard).
• Locate all switch boxes 48" above the finished floor (standard).
For special circumstances, inspectors will allow switch and location measurements to be altered, such as a switch at 36' above the floor in a child's bedroom or receptacles at 24' above the floor to make them more accessible for someone in a wheelchair.
• Install all boxes and conduit fittings so they remain accessible.
• Leave no gaps greater than 'A' between wallboard and front of electrical boxes.
• Place receptacle boxes flush with combustible surfaces.
• Leave a minimum of 8' of usable cable or wire extending past the front of the electrical box.
Wires & Cables (pages 20 to 25)
• Use wires that are large enough for the amperage rating of the circuit (see Wire Size Chart, page 21).
• Drill holes at least 2* back from the exposed edge of joists to run cables through. Do not attach cables to the bottom edge of joists.
• Do not run cables diagonally between framing members.
• Run cable between receptacles 20" above the floor.
• Use nail plates to protect cable that is run through holes drilled or cut into studs less than 1 from front edge of stud.
• Do not crimp cables sharply.
• Contain spliced wires or connections entirely in a plastic or metal electrical box.
• Use wire connectors to join wires.
• Use staples to fasten cables within 8' of an electrical box and every 48" along its run.
• Leave a minimum V,' (maximum 1") of sheathing where cables enter an electrical box.
• Clamp cables and wires to electrical boxes with approved NM clamp. No clamp is necessary for one-gang plastic boxes if cables are stapled within 8".
• Label all cables and wires at each electrical box to show which circuits they serve for the rough-in inspection.
• Connect only a single wire to a single screw terminal. Use pigtails to join more than one wire to a screw terminal.
Switches (pages 42 to 61)
• Use a switch-controlled receptacle in rooms without a built-in light fixture operated by a wall switch.
• Use three-way switches at the top and bottom on stairways with six steps or more.
• Use switches with grounding screw with plastic electrical boxes.
• Locate all wall switches within easy reach of the room entrance.
Receptacles (pages 62 to 77)
• Match the amp rating of a receptacle with the size of the circuit.
• Include receptacles on all walls 24" wide or greater.
• Include receptacles so a 6-feet cord can be plugged in from any point along a wall or every 12-feet along a wall.
• Include receptacles in any hallway that is 10-feet long or more.
• Use three-prong, grounded receptacles for all 15- or 20-amp, 120-volt branch circuits.
• Include a switch-controlled receptacle in rooms without a built-in light fixture operated by a wall switch.
• Install GFCI-protected receptacles in bathrooms, kitchens, garages, crawl spaces, unfinished basements, and outdoor receptacle locations.
• Install an isolated-ground circuit to protect sensitive equipment, like a computer, against tiny power fluctuations. Computers should also be protected by a standard surge protector.
Lighting Fixtures (pages 78 to 95)
• Use mounting straps that are anchored to the electrical boxes to mount ceiling fixtures.
• Keep recessed light fixtures 3" from insulation and 'A' from combustibles.
• Include at least one switch-operated lighting fixture in every room.
Grounding (pages 16 to 17)
• Ground all receptacles by connecting receptacle grounding screws to the circuit grounding wires.
• Use switches with grounding screws whenever possible. Always ground switches installed in plastic electrical boxes and all switches in kitchens, bathrooms, and basements.
• Install a dedicated 40- or 50-amp, 120/240-volt circuit for a range (or two circuits for separate oven and countertop units).
• Install two 20-amp small appliance circuits.
• Install dedicated 15-amp, 120-volt circuits for dishwashers and food disposals (required by many local codes).
• Use GFCI receptacles for all accessible countertop receptacles; receptacles behind fixed appliances do not need to be GFCIs.
• Position receptacles for appliances that will be installed within cabinets, such as microwaves or food disposals, according to the manufacturer's instructions.
• Include receptacles on all counters wider than 12"
• Space receptacles a maximum of 48' apart above countertops and closer together in areas where many appliances will be used.
• Locate receptacles 18" above the countertop. If the backsplash is more than the standard 4" or the bottom of the cabinet is less than 18" from the counter-top, center the box in the space between the countertop and the bottom of the wall cabinet.
• Mount one receptacle within 12" of the countertop on islands and peninsulas that are 12" x 24' or greater.
• Locate at least one receptacle at table height in the dining areas for convenience in operating a small appliance.
• Do not put lights on small appliance circuits.
• Install additional lighting in work areas at a sink or range for convenience and safety.
• Install a separate 20-amp circuit.
• Ground switches in bathrooms.
• Use GFCI-protected receptacles.
• Install at least one ceiling-mounted light fixture.
• Place blower heaters in bathrooms well away from the sink and tub.
• Install a separate 20-amp circuit for a washing machine.
• Install a minimum feed 30-amp #10 THHN wire (see page 154) for the dryer, powered by a separate 120/240-volt major appliance circuit.
• Install metal conduit for cable runs in unfinished rooms.
• Use GFCI-protected receptacles, except for fixed appliances, such as freezers or dryers.
Living Room/Entertainment Rooms/Bedrooms
• Install a minimum of two 20-amp circuits in living rooms.
• Install a minimum of one 15- or 20-amp basic lighting/receptacle circuit for each 600 square feet of living space.
• Install a dedicated circuit for each permanent appliance, like an air conditioner, computer, or group of electric baseboard heaters.
• Do not use standard electrical boxes to support ceiling fans.
• Include receptacles on any wall that is 24* wide or more.
• Space receptacles on basic lighting/receptacle circuits a maximum of 12 feet apart. For convenience you can space them as close as 6 feet.
• Position permanent light fixtures in the center of the room's ceiling.
• Install permanently wired smoke alarms in room additions that include sleeping areas.
• Check for underground utilities before digging.
• Use UF cable for outdoor wiring needs.
• Run cable in rigid metal or schedule 40 PVC plastic (see page 154), as required by local code.
• Bury cables 12" if the circuit is no larger than 20 amps. Bury the cable at least 18' deep if the circuit is larger than 20 amps.
• Use weatherproof electrical boxes with watertight covers.
• Use GFCI-protectec receptacles.
• Install receptacles a minimum of 12" above ground level.
• Anchor freestanding receptacles not attached to a structure by embedding the rigid metal conduit or schedule 40 PVC plastic conduit in a concrete footing, so that it is at least 12", but no more than 18' above ground level.
• Plan on installing a 20-amp, 120-volt circuit if the circuit contains more than one light fixture rated for 300 watts or more than four receptacles.
• Use three-way switches at the top and bottom on stairways with six steps or more.
• Include receptacles in any hallway that is 10 feet long or more.
• Position stairway lights so each step is illuminated.
3: Prepare for Inspections
Electrical inspectors who issue the work permit tor your wiring project will also visit your home to review the work Make sure to allow time for these inspections as you plan the project For most projects. inspectors make two visits
The first inspection, called the rough-in. is done after the cables are run between the boxes, but before the insulation, wallboard. switches, and fixtures are installed The second inspection, called the final, is done after the walls and ceilings are finished and all electrical connections are made
When preparing for the rough-in inspection, make sure the area is neat. Sweep up sawdust and clean up any pieces of scrap wire or cable insulation Before inspecting the boxes and cables, inspectors will check to make sure all plumbing and other mechanical work is completed Some electrical inspectors will ask to see your building and plumbing permits final inspection inspectors check random
!o make sure the wire connections are correct If they see good workmanship at the selected boxes, the inspection will be over quickly However, if they spot a problem, inspectors may choose to inspect every connection
Inspectors have busy schedules, so it is a good idea to arrange for an inspection several days or weeks in advance In addition to basic compliance with code, inspectors expect your work to meet their own standards for quality When you apply for a work permit, make sure you understand what the inspectors will look for during inspections
You cannot put new circuits into use legally until an inspector approves them at the final inspection Because inspectors are responsible for the safety of all wiring installations, their approval means that your work meets professional standards If you have planned carefully and done your work well, electrical inspections are routine visits that give you confidence in your own skills
Inspectors measure to see that electrical boxes are mounted at consistent heights Measured from the center of the boxes, receptacles in living areas typically are located 12 above the finished floor and switches at 48" For special circumstances. inspectors allow you to alter these measurements For example, you can install switches at 36" above the floor in a child s bedroom, or set receptacles at 24 to make them more convenient tor someone in a wheelchair
Inspectors will check cables to see that they are anchored by-cable staples driven within 8 ot each box and every 4 feet thereafter when they run along studs When bending cables tomn the wire in a smooth curve Do not crimp cables sharply or install them diagonally between training members Some inspectors specify that cables running between receptacle boxes should be about 20' above the floor
Electrical box faces should extend past the front of framing members so 'he boxes will be flush with finished walls (left) Inspectors will check to see that an boxes are large enough for the wires they contain Cables should be cut and stripped back so that 8" of usable length extends past the front of the box. and so that at least of sheathing reaches into the box iright) Label all cables to show which circuits they serve inspectors 'ecognize this as a mark of careful work The labels also simplify the final hookups after the waliboard is installed
Install an isolated-ground circuit and receptacle if recommended by your inspector An isolated-ground circuit protects sensitive electronic equipment, like a computer against tiny current fluctuations Computers also should be protected by a standard surge protector
Room addition living area
Recommended total heating rating
Recommended circuit size
Recommended air-conditioner rating
Recommended circuit size
100 sq. feet
Was this article helpful?