Department of Community Development  Inspection Services Division 3805 S. Casper Drive  New Berlin  WI  53151 Phone: 262-797-2445  Fax: 262-780-4612  www.newberlin.org/dcd

Basic Codes for in Residential Dwellings

NOTE: This is only a brief overview and it is not intended for use as an instruction guide. 1. Make sure the electrical service panel has the proper ampacity to deliver power to the existing loads plus your additional loads (Article 220 of the N.E.C.1 contains the method of calculating the service area). 2. Make sure there are open spaces in your service panel or distribution system to properly supply the additional loads. Under no circumstance is more than one conductor allowed under a lug, screw, or terminal unless they are identified for such use (N.E.C. 110-14[a]). The service panel shall be free of any objects in front of it. No branch piping, etc. shall be placed closer than 36 inches from the front service, floor to ceiling. 3. All wiring methods have different code requirements regarding their installations. Requirements are listed in Chapter 3 of the N.E.C. The most common wiring method in a residence is romex, also known as NM Cable or NM-B Cable. Romex must closely follow the building surfaces and must be supported at intervals not exceeding 4 ½ feet and within 12 inches from every metal box or panel termination. Romex must be supported within 8 inches of every plastic box. Where run parallel with joists, it may be run on the sides of joists, where run is perpendicular to joist, it must be run through bored holes. Bored holes must be a minimum of 1 ¼ inches from the surface of the framing member to prevent penetration by screws and nails. Where subject to physical damage, romex must be protected by conduit. (An example of where Romex would need to be protected would be where it drops from a basement ceiling to supply a surface mounted outlet, or a furnace, or underneath a kitchen sink supplying a disposal). 4. Junction boxes and device boxes are selected by the number of or outlets (devices) in that box and the number of conductors entering that box. The boxes must have a cubic inch capacity large enough to handle the box fill in accordance with N.E.C. Article 370-16. Plastic boxes generally have the cubic inch capacity marked inside the box, along with the number of commonly used conductors that the box may contain. But, remember that each device ( or plug) must be counted as 2 conductors and all equipment grounding conductors (bare) must be counted as 1. Example: Installing an outlet in a device box with the dimensions of 3 x 2 x 2 ¾ = 14.0 cu. in. 2- #12-2 (with ) cables enter the box. Each cable has 2 conductors (2 x 2 = 4) 4 All grounds count as 1 1 The outlet counts as 2 2 wires 7 wires TOTAL 7 - #12 wires require 15.75 cu. in. (7 x 2.25 = 15.75), therefore, this 14.0 cu. in. box may not be used. 5. All conductors in a box must have at least 6” of free conductors for splicing or connection of devices. (N.E.C. 300-14). 6. All metallic boxes must be bonded to the equipment grounding conductor by the threaded hole with an approved bonding screw in the back of the box or by an approved means. 7. Outlet spacing requirements are found in N.E.C. 210-52, and lighting provision requirements are found in N.E.C. 210-70. An outlet must be present within the reach of a six foot appliance cord.

The above referenced guidelines are not to be considered as complete or all inclusive. The items listed are a guide to help in planning your project. - 1 - P:\DCD\Inspection\Master forms binder\Guidelines 2011\Electrical Wiring in Residential Dwellings.doc Last printed 6/22/2011 9:58:00 AM Department of Community Development  Inspection Services Division 3805 S. Casper Drive  New Berlin  WI  53151 Phone: 262-797-2445  Fax: 262-780-4612  www.newberlin.org/dcd

8. Boxes recessed in walls or ceilings with a drywall or plaster finish must be installed so the front edge of the box will not be set back more than ¼ inch from the finished surface. (N.E.C. 370- 20). Boxes installed on walls with a wood or paneled surface must be flush with combustible surface. 9. All junction boxes must be accessible without removing any part of the building. (Above a suspended lay-in tile ceiling is considered accessible). (N.E.C. 370-18). 10. All unused openings in junction boxes or any electrical distribution equipment must be closed. (N.E.C.370-18). 11. All outlets in an unfinished basement must be protected by a GFCI. 12. All outlets added in a garage must be GFCI protected. (N.E.C.210-8 [a][2]). An exception permits the cord and plug connected equipment occupying dedicated space and garage door openers to be unprotected. 13. All outlets installed outdoors must be GFCI protected. (N.E.C. 210-8 [a][3]). 14. Any outlets installed in a kitchen to serve counter top space must be GFCI protected. All outlets at kitchen counters must not exceed 4 feet from outlet to outlet. Every 12 inch wide counter space requires an outlet. 15. Any outlets installed in a bathroom must have GFCI protection (N.E.C. 210-8 [a][1]) and be supplied by a separate 20 amp circuit. 16. A rough inspection is required for any electrical work that is to be covered by a wall covering, ceiling covering, or buried in a trench. For the rough inspection, all wires must be spiced out in the box and ready for the device installation. A final inspection is required on all wiring.

These are meant as basic wiring guidelines. The 900+ page National (N.E.C.) document is available for your purchase from the National Fire Protection Association. Also, many Technical School book stores will have Electrical books for purchase.

The above referenced guidelines are not to be considered as complete or all inclusive. The items listed are a guide to help in planning your project. - 2 - P:\DCD\Inspection\Master forms binder\Guidelines 2011\Electrical Wiring in Residential Dwellings.doc Last printed 6/22/2011 9:58:00 AM