PERMISSIBLE LOADS ON BRANCH CIRCUITS BASED ON NEC BASICS AND TUTORIALS

The NEC is very specific about the loads permitted on branch circuits. Here is a recap of these requirements.

• The load shall not exceed the branch-circuit rating.

• The branch circuit must be rated 15, 20, 30, 40, or 50 amperes when serving two or more outlets, NEC 210.3.

• An individual branch circuit may supply any size load.

• 15- and 20-ampere branch circuits


a. may supply lighting, other equipment, or both types of loads.
b. for cord-and-plug-connected equipment, shall not exceed 80% of the branch-circuit rating.
c. for equipment fastened in place, shall not exceed 50% of the branch-circuit rating if the branch circuit also supplies lighting, other cord-and-plug-connected equipment, or both types of loads.

• The 20-ampere small-appliance circuits in homes shall not supply other loads, NEC 210.11(C)(1).

• 30-ampere branch circuits may supply equipment such as dryers, cooktops, water heaters, and so forth. Cord-and-plug-connected equipment shall not exceed 80% of the branch-circuit rating.

• 40- and 50-ampere branch circuits may supply cooking equipment that is fastened in place, such as an electric range, as well as HVAC equipment.

• Over 50-ampere-rated branch circuits are for electric furnaces, large heat pumps, air-conditioning equipment, large double ovens, and similar large loads.

Comments

Post a Comment

Popular posts from this blog

POLYMERIC INSULATON OF POWER CABLES BASICS AND TUTORIALS

This type of cable can be classified as follows: 1. NEC compounds 2. Elastomers 3. Thermoplastics 4. Thermosettings The rubber and rubber-like insulated cables enjoy their popularity owing to moisture resistance, ease of handling, ease of splicing, and extreme flexibility. Elastomers are materials that can be compressed, stretched, or deformed like rubber and yet retain their original shape. The thermoplastics materials soften when they are reheated, whereas thermosetting-type insulation has very little tendency to soften upon reheating after vulcanization. The earlier oil-based natural rubber compounds have been replaced by synthetic materials, which have better electrical and mechanical characteristics. The following synthetic rubber-like compounds are in use today: Ethylene propylene rubber (EPR) , an elastomer compound: EPR is commonly used in power cables, but is also gaining use in telecommunications and other types of cables. EPR possesses good chemical,...
Read more

ENTRY LEVEL and SENIOR ENGINEERING JOBS

Hello there. On this blog, i will try to compress and collect any available engineering jobs out there with emphasis on the entry level. USA JOBS 1 USA JOBS 2 USA JOBS 3 M.E. JOBS 1 M.E. JOBS 2 M.E. JOBS 3 note: I am in no way related to these job hiring poster.
Read more

SURGE ARRESTER ENERGY HANDLING CAPABILITY FOR TRANSMISSION AND DISTRIBUTION LINES APPLICATION TUTORIALS

Image
Photo Courtesy of http://www.classiclightningprotection.com/index.html Metal oxide arresters protect the equipment from high voltage surges by absorbing the energy from the surge. Hence, the energy handling capability (or also called "energy absorption capability" or "energy withstand capability") is an important consideration in the design and application of metal oxide arresters. Most manufacturers publish energy capability values of arresters. However, there are no specified tests either in IEEE/ANSI, or IEC standards. Hence, there is confusion in using these important application parameters. Both IEEE and IEC are contemplating writing standardized tests for the arrester energy handling capability. When metal oxide arresters are energized, valve elements of the arrester will absorb energy which results in a temperature increase of the valve elements. Under normal operating conditions (i.e. absence of overvoltage) there is a balance between the heat...
Read more
free counters