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SYMBOLS AND NOTATIONS
The architect uses symbols and notations to simplify the drawing and presentation of information concerning electrical devices, appliances, and equipment. For example, an electric range outlet symbol is shown in FIG. 6.
Most symbols have a standard interpretation throughout the country as adopted by ANSI. Symbols are described in detail in section 2.
A notation will generally be found on the plans (blueprints) next to a specific symbol calling attention to a variation, type, size, quantity, or other necessary information. In reality, a symbol might be considered to be a notation because symbols represent words, phrases, numbers, quantities, and so on.
Another method of using notations to avoid cluttering up a blueprint is to provide a system of symbols that refer to a specific table. For example, the written sentences on plans could be included in a table referred to by a notation. Figure 10 is an example of how this could be done. The special symbols that refer to the table would have been shown on the actual plan.
FIG. 6 An electric range outlet symbol.
NATIONAL ELECTRICAL CODE (NEC)
The NEC is the electrical Code standard recognized by everyone in the electrical industry.
The first sentence in the NEC is found in 90.1.
This sentence lays the foundation for all electrical installations. It states: The purpose of this Code is the practical safeguarding of persons and property from hazards arising from the use of electricity. It goes on to state that the NEC contains provisions that are considered necessary for safety and that compliance therewith and proper maintenance will result in an installation that is essentially free from hazard but not necessarily efficient, convenient, or adequate for good service or future expansion of electrical use.* As you study this text, you will learn how to "Meet Code" for wiring a typical house, not "Beat Code." As NEC requirements are discussed throughout this text, the sheer number of Code references can become mind-boggling. To simplify using this text as a reference, in addition to the conventional "subject" index at the back of the text, there is a Cross Index, making it easy for you to pinpoint specific Code sections and articles found in this text.
The NEC is published by the National Fire Protection Association and is referred to as NFPA 70. The NEC was first published in 1897. It is revised every 3 years so as to be as up to date as possible. The NEC does not become law until adopted by official action of the legislative body of a city, municipality, county, or state. Because of the ever-present danger of fire or shock hazard through some failure of the electrical system, the electrician and the electrical contractor must use listed materials and must perform all work in accordance with recognized standards.
One- and Two-Family Dwelling Electrical Code
NFPA 70A is the National Electrical Code Requirements for One- and Two-Family Dwellings.
It is a condensed version of the NEC that contains excerpts directly from the NEC NFPA 70. It includes requirements and tables that relate only to house wiring. It does not include Code requirements for other types of construction.
Other Electrical Codes
In addition to the NEC, you must also consider local and state electrical codes.
Code Arrangement
It is important to understand the arrangement of the NEC.
Easy to Find Things!
Finding things in the current edition of the NEC is much easier than in past editions. All articles in section 3 of the NEC cover wiring methods.
In each article, the same section number has been assigned for a particular requirement. Here are a few examples:
• Scope is found in XXX.1 such as 320.1, 330.1 and 344.1
• Definitions (if present in the Article) are found in XXX.02
• Permitted Uses are found in XXX.10.
• Uses Not Permitted are found in XXX.12.
• Securing and Supporting is found in XXX.30.
This is referred to as "the parallel numbering system."
How to Spot Changes in the 2011 NEC
Highlighted text makes it easy to quickly spot where changes in the NEC have been made from the previous edition.
Who Writes the Code?
For each Code cycle, the NFPA solicits proposals from anyone interested in electrical safety. Anyone may submit a proposal to change the NEC using the Proposal Form found in the back of the NEC. A form may also be downloaded from www.nfpa.org. Proposals received are then given to a specific Code-Making Panel (CMP) to accept, reject, accept in part, accept in principle, or accept in principle in part. These actions are published in the Report on Proposals (ROP) and may be downloaded from www.nfpa.org. Individuals may send in their comments on these actions using the Comment Form found in the ROP. The CMPs meet again to review and take action on the comments received. These actions are published in the Report on Comments (ROC) and also may be downloaded from nfpa.org. Final action (voting) on proposals and comments is taken at the NFPA annual meeting.
However, before the NEC is published, if there is disagreement on any specific Code requirement adopted through the above process, NFPA will consider an Appeal that is reviewed and acted upon by the NFPA Standards Council about 6 weeks after the annual meeting. After an Appeal is acted upon by the Standards Council, should there still be controversy, another step not often used in the Code adoption process is a petition that is reviewed and acted upon by the NFPA Board of Directors.
Individuals who serve on CMPs are electrical inspectors, electrical contractors, electrical engineers, individuals from utilities, manufacturers, testing laboratories, the Consumer Product Safety Commission, insurance companies, and similar organizations. CMP members are appointed by the NFPA. The CMPs have 10 to 20 principal members, plus a similar number of alternate members. All of the CMPs have a good balance of representation.
Which Edition of the NEC to Use
This text is based on the 2011 edition of the NEC. Some municipalities, cities, counties, and states have not yet adopted this edition and may continue using older editions. Check with your local electrical inspector to find out which edition of the Code is in force.
Copies of the latest edition of the NEC NFPA 70 may be ordered from the following:
National Fire Protection Association 1 Batterymarch Park Quincy, MA 02269-9101 Phone: 617-770-3000
International Association of Electrical Inspectors 901 Waterfall Way, Suite 602 Richardson, TX 75080-7702 Phone: 800-786-4234
iaei.org
Electrical Inspection Code for Existing Dwellings
This code is published by the NFPA and is referred to as NFPA 73. It is a brief nine-page code that provides requirements for evaluating installed electrical systems within and associated with existing dwellings to identify safety, fire, and shock hazards-such as improper installations, overheating, physical deterioration, and abuse.
This code lists most of the electrical things to inspect in an existing dwelling that could result in a fire or shock hazard if not corrected. It only points out things to look for that are visible. It does not get into examining concealed wiring that would require removal of permanent parts of the structure. It also does not get into calculations, location requirements, and complex topics as does the NEC NFPA 70.
This code can be an extremely useful guide for electricians doing remodel work and for electrical inspectors wanting to bring an existing dwelling to a reasonably safe condition. Many localities require that when a home changes ownership, the wiring must be brought up to some minimum standard, but not necessarily as extensively as would be the case for new construction.
Homes for the Physically Challenged
The NEC does not address the wiring of homes for the physically or mentally challenged or disabilities associated with the elderly.
Each installation for the physically challenged must be based on the specific need(s) of the individual(s) who will occupy the home. Some physically challenged people are bedridden, require the mobility of a wheelchair, have trouble reaching, have trouble bending, and so forth. There are no hard and fast rules that must be followed-only many suggestions to consider.
Some of these follow:
• Install more ceiling luminaires instead of switching receptacles. Cords and lamps are obstacles.
• Install luminaires having more than one bulb.
• Go "overboard" in the amount of lighting for all rooms, entrances, stairways, stairwells, closets, pantries, bathrooms, and so on.
• Use higher wattage bulbs-not to exceed the wattage permitted in the specific fixture.
• Consider installing luminaires in certain areas (such as bathrooms and hallways) to be con trolled by motion detectors.
• Consider installing exhaust fans in certain areas (such as laundries, showers, and bathrooms) that turn on automatically when the humidity reaches a predetermined value.
• Consider the height of switches and thermostats, usually 42 in. (1.0 m) or lower, instead of the standard 46-52 in. (1.15-1.3 m).
• Consider rocker-type switches instead of toggle type.
• Install pilot light switches.
• Consider "jumbo" switches.
• Be sure stairways and stairwells are well lit.
• Consider stair tread lighting.
• Position lighting switches so as not to be over stairways or ramps.
• Locate switches and receptacles to be readily and easily accessible-not behind doors or other hard-to-reach places.
• Consider installing wall receptacle outlets higher 24-27 in. (600-675 mm) than normal 12 in. (300 mm) height.
• Install lighted doorbell buttons.
• Chimes: Consider adding a strategically located "dedicated" lamp(s) that will turn on when door bell buttons are pushed. The wiring diagram for this is found in Figure 25-25.
• Telephones: Consider adding visible light(s) strategically located that will flash at the same time the telephone is ringing.
• Consider installing receptacle outlets and switches on the face of kitchen cabinets. Wall outlets and switches can be impossible for the physically challenged person to reach.
• Consider fire, smoke, and security systems directly connected to a central office for fast response to emergencies that do not depend on the disabled to initiate the call.
• Consider installing the fuse box or breaker-panel on the first floor instead of in the basement.
• Consider the advanced home systems concept of remote control of lighting, receptacles, appliances, television, telephones, and so on.
The control features can make life much easier for a disabled person.
When involved with multifamily dwellings, check with your local building authority. They will have copies of the Americans with Disabilities Act (ADA) from the U.S. Department of Justice and the Fair Housing Act from the U.S. Department of Housing and Urban Development (HUD) that basically require that all units must have accessible light switches, electrical outlets, thermostats, and other environmental controls.
The ANSI publication ANSI A117.1-2003, Standard for Accessible and Useable Buildings and Facilities, contains many suggestions and considerations for buildings and facilities for the physically challenged. This and other standards can be ordered from
American National Standards Institute 25 West 43rd Street New York, NY 10036; Tel: 212-642-4900; Fax: 212-398-0023
The same standard is available from the International Code Council (ICC) under the publication number ICC/ANSI A117.1-2003.
Another virtually unlimited source of standards is Global Engineering Documents; 15 Inverness Way East Englewood, CO 80112
Phone: 800-624-3974 ext. 1950
303-792-2181 ext. 1950 Fax: 303-792-2192
global.ihs.com
BUILDING CODES
The majority of the building departments across the country have for the most part adopted the NEC rather than attempting to develop their own electrical codes. As you study this text, you will note numerous references to the NEC, the electrical inspector, or the authority having jurisdiction.
An authority's level of knowledge varies. The electrical inspector may be full-time or part-time and may also have responsibility for other trades, such as plumbing or heating. The heads of the building departments in many communities are typically called the Building Commissioners or Directors of Development. Regardless of title, they are responsible for ensuring that the building codes in their communities are followed.
International Code Council (ICC)
Rather than writing their own codes, most communities for the most part adopt the codes of the International Code Council (ICC). Over the years, the ICC has developed comprehensive and coordinated model construction codes. These include building, mechanical, plumbing, fire, energy conservation, existing building, fuel gas, sewage disposal, property maintenance, zoning, residential, and electrical codes. The ICC provides technical, educational, and informational products. Its address is:
ICC Headquarters
500 New Jersey Avenue, NW, 6th Floor Washington, DC 20001
Phone: 888-422-7233
iccsafe.org
The ICC International Residential Code, sections 33-42, contains electrical provisions that were written and produced under the guidance of the NFPA. The material in these sections is copy righted by the NFPA. These provisions are similar to the NEC other than the layout and numbering system.
Electrical Wiring-Residential is based on the NEC.
Because local electrical codes may differ from the NEC, you should check with the local inspection authority to determine which edition of the NEC is enforced, and what, if any, local requirements or amendments take precedence over the NEC.
American National Standards Institute
The American National Standards Institute (ANSI) is an organization that coordinates the efforts and results of the various standards developing organizations, such as those mentioned in previous paragraphs. Through this process, ANSI approves standards that then become recognized as American National Standards. One will find much similarity between the technical information found in ANSI standards, the UL standards, the International Electronic and Electrical Engineers standards, and the NEC.
International Association of Electrical Inspectors
The International Association of Electrical Inspectors (IAEI) is a nonprofit organization. The IAEI membership consists of electrical inspectors, building officials, electricians, engineers, contractors, and manufacturers throughout the United States and Canada. The major goal of the IAEI is to improve the understanding of the NEC. Representatives of this organization serve as members of the various CMPs of the NEC and share equally with other members in the task of reviewing and revising the NEC.
The IAEI publishes a bimonthly magazine- The IAEI News. It is devoted entirely to electrical code topics. Anyone in the electrical industry is welcome to join the IAEI. An application form is found after the Appendix of this text. Its address is International Association of Electrical Inspectors
901 Waterfall Way, Suite 602 Richardson, TX 75080-7702
Phone: 800-786-IAEI
iaei.org
Code Definitions
The electrical industry uses many words (terms) that are unique to the electrical trade. These terms need clear definitions to enable the electrician to understand completely the meaning intended by the Code.
Article 100 of the NEC is a "dictionary" of these terms. Article 90 also provides further clarification of terms used in the NEC. Here are a few examples:
Ampacity: The maximum current, in amperes, that a conductor can carry continuously under the conditions of use without exceeding its temperature rating.
Approved: Acceptable to the authority having jurisdiction.
Authority Having Jurisdiction (AHJ): An organization, office, or individual responsible for enforcing the requirements of a code or standard, or for approving equipment, materials, an installation, or a procedure. See NEC 90.4.
Dwelling Unit: A single unit, providing complete and independent living facilities for one or more pro visions for living, sleeping, cooking, and sanitation.
Informational Note: Informational Notes are found throughout the Code. Informational Notes are "explanatory" in nature, in that they refer to other sections of the Code. They also describe things where further description is necessary. See 90.5.
Informational Notes are not to be enforced.
Listed: Equipment, materials, or services included in a list published by an organization that is accept able to the authority having jurisdiction and concerned with evaluation of products or services, that maintains periodic inspection of production of listed equipment or materials or periodic evaluation of services, and whose listing states that either the equipment, material, or services meets appropriate designated standards or has been tested and found suitable for a specified purpose.
Shall: Indicates a mandatory rule, 90.5. As you study the NEC, think of the word "shall" as meaning "must." Some examples found in the NEC where the word "shall" is used in combination with other words are: shall be, shall have, shall not, shall be permitted, shall not be permitted, and shall not be required.
Refer to Key Terms in the Appendix of this text.
Read 110.3(B) Carefully!
One of the most far-reaching NEC rules is 110.3(B). This section states that Listed or labeled equipment shall be installed and used in accordance with any instructions included in the listing or labeling. This means that an entire electrical system and all of the system's electrical equipment must be installed and used in accordance with the NEC and the numerous standards to which the electrical equipment has been tested.
METRICS (SI) AND THE NEC
The United States is the last major developed country in the world not using the metric system of weights and measures as the primary system. For most of our lifetime, we have used the English system of weights and measures, also referred to as inch-pound and U.S. Customary. But this is changing! Manufacturers are now showing both inch pound and metric units in their catalogs. By law, plans and specifications for new governmental construction and renovation projects have used the metric system since January 1, 1994.
You may not feel comfortable with metric measurements, but metric measurements are here to stay. You might just as well become familiar with the metric system.
All measurements in the NEC are shown in both inch-pound and metric values.
For more information about metrics, refer to the "Metric System of Measurement" section found in the Appendix of this text.
Table 1 Comparison of trade size vs. actual inside diameters.
Table 2 Trade sizes of raceways and their metric designator identification.
METRIC DESIGNATOR AND TRADE SIZE
Metric Designator Trade Size
Table 3 Comparison of knockout trade size vs. actual measurement.
Conduit knockouts in boxes do not measure up to what we call them. Table 3 shows some examples.
Outlet boxes and device boxes use their nominal measurement as their trade size. For example, a 4 in. 3 4 in. 3 1 1/2 in. does not have an internal cubic-inch volume of 4 in. 3 4 in. 3 1 1/2 in. 5 24 in^3.
Table 314.16(A) shows this size box as having a 21-cubic-in. volume. This table shows trade sizes in two columns-millimeters and inches.
In this text, a square outlet box is referred to as trade size 4 3 4 3 1 1/2. Similarly, a single-gang device box would be referred to as a trade size 3 3 2 3 3 box.
Trade sizes for construction material will not change. A 2 3 4 is really a name, not an actual dimension. A 2 3 4 will keep its name forever. This is its trade size.
In this text, most measurements directly related to the NEC are given in both inch-pound and metric units. In many instances, only the inch-pound units are shown. This is particularly true for the examples of raceway and box fill calculations, load calculations for square foot areas, and on the plans (drawings).
Because the NEC rounded off most metric con version values, a calculation using metrics results in a different answer when compared to the same calculation done using inch-pounds. For example, load calculations for a residence are based on 3 volt amperes per square foot or 33 volt-amperes per square meter.
For a 40 ft 3 50 ft dwelling: 3 VA 3 40 ft 3 50 ft 5 6000 volt-amperes.
In metrics, using the rounded off values in the NEC: 33 VA 3 12 m 3 15 m 5 5940 volt-amperes.
The difference is small, but, nevertheless, there is a difference.
To show calculations in both units throughout this text would be very difficult to understand and would take up too much space. Calculations in either metrics or inch-pounds are in compliance with the NEC, 90.9(D). In 90.9(C)(3) we find that metric units are not required if the industry practice is to use inch-pound units.
It is interesting to note that the examples in section 9 of the NEC use inch-pound units, not metrics.
Guide to Metric Usage
The metric system is a "base-10" or "decimal" system in that values can be easily multiplied or divided by 10 or "powers of 10." The metric system as we know it today is known as the International System of Units (SI), derived from the French term "le Système International d'Unités." In the metric system, the units increase or decrease in multiples of 10, 100, 1000, and so on.
For instance, one megawatt (1,000,000 watts) is 1000 times greater than one kilowatt (1000 watts).
By assigning a name to a measurement, such as a watt, the name becomes the unit. Adding a prefix to the unit, such as kilo, forms the new name kilowatt, meaning 1000 watts. Refer to Table 4 for prefixes used in the metric system.
The prefixes used most commonly are centi, kilo, and milli. Consider that the basic unit is a meter (one). Therefore, a centimeter is 0.01 meter, a kilometer is 1000 meters, and a millimeter is 0.001 meter.
Some common measurements of length and equivalents are shown in Table 5.
Electricians will find it useful to refer to the conversion factors and their abbreviations shown in Table 6.
Refer to the Appendix of this text for a comprehensive metric conversion table. The table includes information on how to "round off" numbers for practical use on the job.
Table 4 Metric prefixes, symbols, multipliers, powers, and values.
Table 5 Some common measurements of length and their equivalents.
Table 6 Useful conversions and their abbreviations.
NATIONALLY RECOGNIZED TESTING LABORATORIES (NRTL)
How does one know if a product is safe to use? Manufacturers, consumers, regulatory authorities, and others recognize the importance of independent, "third-party" testing of products in an effort to reduce safety risks. Unless you have all of the necessary test equipment and knowledge of how to properly test a product for safety, the surest way is to accept the findings of a third-party testing agency.
Nationally Recognized Testing Laboratories (NRTL) have the knowledge, wherewithal, and test equipment to test and evaluate products for safety.
A NRTL will perform tests on a product based on a specific nationally recognized safety standard. After the product has been tested and found to comply with the safety standard, the product is considered to be free from reasonably foreseeable risk of fire, electric shock, and related hazards. The product is then "listed" and will have a listing marking (label).
As you work with electrical products, make sure the product has a listing marked on it from a NRTL. If the product is too small to have a listing mark on the product itself, then look for the mark on the car ton the product came in.
The following laboratories do a considerable amount of testing and listing of electrical equipment:
Underwriters Laboratories, Inc. (UL) Underwriters Laboratories, Inc. (UL), founded in 1894, is a highly qualified, nationally recognized testing laboratory with several testing laboratories in the United States and service locations in several other countries. UL develops product safety standards, and performs tests to these standards. Most reputable manufacturers of electrical equipment submit their products to UL, where the equipment is subjected to numerous tests. These tests deter mine whether the product can perform safely under normal and abnormal conditions to meet published standards. After UL tests and evaluates a product, and determines that the product complies with the specific standard, the manufacturer is then permitted to label its product with the UL Mark (FIG. 7). The products are then listed in a UL Directory.
UL Marking. The UL marking is required to be on the product! The UL marking will always consist of four elements-UL in a circle, the word "LISTED" in capital letters, the product identity, and a unique alphanumeric control or issue number. If the product is too small, or has a shape or is made of a material that will not accept the UL Mark on the product itself, the marking is permitted on the smallest unit carton or container that the product comes in.
Marking on the carton or box is nice but does not ensure that the product is UL listed! The letters will always be staggered: UL. They will not be side by side: UL. The listing mark shown in FIG. 7 indicates the product is in compliance with the applicable product safety standards in the United States and in Canada. A listing mark with only UL in a circle indicates the product has been evaluated to only US standards.
When UL tests and lists products that comply to the requirements of a particular CSA standard, the UL logo shown in FIG. 7 will appear with a "C" outside of and to the left of the circle. This means the product has been tested and evaluated for compliance only with Canadian requirements.
Product standards are being harmonized in North America as a result of the North American Free Trade Act (NAFTA). Discussions are also going on with Mexico. When all of this is finalized, electrical equipment standards may be the same in the United States, Canada, and Mexico.
FIG. 7 The Underwriters Laboratories mark. (Underwriters Laboratories, Inc.)
Additional efforts are being made to harmonize North American standards with those of Europe.
Counterfeit Products. Be on the lookout for counterfeit electrical products. These products have not been tested and listed by a recognized testing laboratory. They can present a real hazard to life and property. Most counterfeit products as of this writing supposedly come from China. Counterfeit electrical products might also be referred to as "black market products." Look for unusual logos or wording. For example, the UL logo might be illustrated in an oval instead of a circle, or the UL logo might not be encircled with anything, or the wording might say approved instead of LISTED. UL doesn't approve anything! It tests the product. If the product meets UL standards, the product is then LISTED. The UL marking might be on the carton and not on the product. Marking on the carton or box is nice, but it can be considered advertising! Absence of the manufacturer's name should raise the caution flag.
Currently, there is federal legislation in progress that would make it a criminal offense to traffic in counterfeit products and counterfeit trademarks. The legislation makes it mandatory that the counterfeit products and any tools that make the products or markings be seized and destroyed.
To learn more about counterfeits, check out ul.com, then search on (type in) the word "counterfeit." Also, check out: nema.org, then type in the word "counterfeit".
UL does not approve a product. Rather, UL lists those products that conform to a specific safety standard. A UL Listing Mark on a product means that representative samples of the product have been tested and evaluated to nationally recognized safety standards with regard to fire, electric shock, and related safety hazards.
FIG. 8 The recognized components mark.
Do not confuse a UL marking in a circle with the markings found on recognized components.
Recognized components that have passed certain tests are marked with the letters RU printed backwards (FIG. 8). By themselves, recognized components are not to be field-installed. They are intended for use in end-use products or systems that would ultimately be tested and listed, with the final assembly becoming a UL-listed product. Some examples of recognized components are relays, ballasts, insulating materials, special switches, and so on.
Useful UL publications are Electrical Construction Equipment Directory (Green Book).
Electrical Appliance and Utilization Equipment Directory (Orange Book).
Guide Information for Electrical Equipment Directory (White Book).
It is extremely useful for an electrician, an electrical contractor, and/or an electrical inspector to refer to these directories when looking for specific requirements, permitted uses, limitations, and others for a certain product.
Many times the answer to a product-related question that cannot be found in the NEC can be found in one of these directories.
The Green and Orange Directories provide technical information about a particular product, and they list the names and addresses of manufacturers and the manufacturers' identification numbers. The White Book provides technical information regarding a product but does not show manufacturers' names and addresses.
The best companion to the NEC is probably the UL White Book (FIG. 9).
These directories can be obtained by contacting:
Underwriters Laboratories, Inc.
333 Pfingsten Road Northbrook, Illinois 60062-2096
Phone: 847-272-8800
Underwriters Laboratories, Inc., and the Canadian Standards Association (CSA) have worked out an agreement whereby either agency can test, evaluate, and list equipment for the other agency. For example, UL might test and list an air conditioner unit to the requirements of UL Standard 1995 (Heating and Cooling Equipment) because the Canadian Standard C22.2 No. 236-M90 is a mirror image of UL Standard 1995. One by one, the UL and CSA Standards are becoming similar.
CSA International
In ways, Canadian Standards Association International is the Canadian counterpart of Underwriters Laboratories, Inc., in the United States.
CSA International is the source of the Canadian Electrical Code (CEC) and of the Canadian Standards for the testing, evaluation, and listing of electrical equipment in Canada. The Canadian Electrical Code is quite different from the NEC. A Canadian version of Electrical Wiring-Residential is available in Canada.
FIG. 10 is a representation of the CSA listing mark. Like the UL listing mark, the appearance of "C" and "US" at the approximately 4:00 and 8:00 o'clock positions indicates what nation's standards the equipment has been evaluated.
The Canadian Electrical Code and CSA standards can be obtained by contacting CSA International 178 Rexdale Boulevard Toronto, Ontario, CANADA M9W 1R3
Phone: 416-747-4044; 800-463-6727
Fax: 416-747-2510
csa-international.org
FIG. 10 The listing mark of Canadian Standards Association.
(Courtesy Canadian Standards Association)
FIG. 11 The listing mark of Intertek Testing. (Courtesy Intertek)
Intertek Testing Services
ITS is a nationally recognized testing laboratory. Its Intertek ETL division provides testing, evaluation, labeling, listing, and follow-up service for the safety testing of electrical products. This is done in conformance to nationally recognized safety standards.
The ETL listing mark, like the UL and CSA listing marks, indicates which nation's product safety standards the equipment has been found to be in compliance with. See FIG. 11.
Information can be obtained by contacting Intertek Testing Services, NA, Inc. ETL SEMKO 3933 US Route 11 Cortland, NY 13045, Phone: 607-753-6711
National Electrical Manufacturers Association
The National Electrical Manufacturers
Association (NEMA) represents nearly 600 manufacturers of electrical products. NEMA develops electrical equipment standards, which, in many instances, are very similar to UL and other consensus standards.
NEMA has representatives on the CMPs for the NEC. Additional information can be obtained by contacting National Electrical Manufacturers Association; 1300 North 17th Street, Suite 1847 Rosslyn, VA 22209; Phone: 703-841-3200
World Wide Web Sites
A comprehensive list of World Wide Web sites for manufacturers, organizations, and inspection and testing agencies is provided in the back of this text.
REVIEW
Note: Refer to the NEC or the plans in the back of this text where necessary.
1. What is the purpose of specifications?
2. Refer to the specifications in the back of this text following section 32.
a. What electrical codes must be conformed to?
b. What is the wiring method to be used in the workshop?
c. What size conductors are to be used for the lighting branch circuits? ___ AWG the small-appliance branch circuits? ____ AWG
d. What section of the specifications tells us the size of the service entrance to be installed for this residence?
3. What is done to prevent a plan from becoming confusing because of too much detail?
4. Name three requirements contained in the specifications regarding material.
a.
b.
c.
5. The specifications state that all work shall be done ________
6. What phrase is used when a substitution is permitted for a specific item?
7. What is the purpose of an electrical symbol?
8. What is a notation?
9. Where are notations found?
10. List at least 12 electrical notations found on the plans for this residence. Refer to the plans at the back of the text.
11. What three parties must be satisfied with the completed electrical installation?
a.
b.
c.
12. What code sets standards for electrical installation work?
13. What authority enforces the requirements set by the NEC?
14. Does the NEC provide minimum or maximum standards?
15. What do the letters UL signify?
16. What section of the NEC states that all listed or labeled equipment shall be installed or used in accordance with any instructions included in the listing or labeling?
17. When the word "shall" appears in a NEC reference, it means that it (must)(may) be done. (choose the correct word.)
18. What is the purpose of the NEC?
19. Does compliance with the NEC always result in an electrical installation that is adequate, safe, and efficient? Why?
20. Name two nationally recognized testing laboratories.
21. a. Do Underwriters Laboratories and the other recognized testing laboratories "approve" products?
b. What do these testing laboratories do?
22. a. Has the NEC been officially adopted by the community in which you live? _______
b. By the state in which you live? ____
c. If your answer is YES to (a) or (b), are there amendments to the NEC? ___
d. If your answer is YES to (c), list some of the more important amendments.
23. Does the NEC make suggestions about how to wire a house that will be occupied by handicapped persons?
24. A junction box on a piece of European equipment is marked 200 cm^3. Convert this to cubic inches.
25. Convert 4500 watts to Btu/hour.
26. You will learn in section 3 that residential lighting loads are based on 3 volt-amperes per ft^2 (33 volt-amperes per m2 ). Determine the minimum lighting load required for an area of 186 m^2. Do calculations for both feet squared and meters squared so you can see the difference in answers. To convert meters squared to feet squared, refer to Table 6.
SAFETY RELATED QUESTIONS
27. What federal organization dictates requirements for work-related safety issues? Circle the correct answer.
a. NEC
b. OSHA
c. IAEI
28. What can you do to reduce or eliminate the possibility of receiving an electric shock when working on electrical circuits? Circle the correct answer.
a. Turn off the power on the circuit you are working on.
b. Turn off the power on the circuit you are working on, tag it, and lock the disconnect in the "OFF" position.
c. Turn off the power on the circuit you are working on, then tell everyone else working with you not to turn the power back on.
29. What is the NEC definition of a qualified person?
30. Are you a qualified person? Explain your answer.
31. Are low-voltage systems totally safe? Explain.
32. What NFPA standard specifically covers safety in the workplace?
33. What do the letters PPE stand for?
34. Explain briefly what an "arc flash" is.
35. Where might you obtain information about on-the-job safety and safety training?
36. a. Is it a safe practice to use a step ladder in which the spreaders have not been fully locked into position? ___
b. If the ladder collapses, who is at fault?
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