Branch Circuit Flashcards
True or False: The rating of a branch circuit is determined by the maximum ampere rating of the overcurrent protective device and ALSO by the size of the conductors used for the branch-circuit
FALSE: The rating of a branch circuit is determined by the maximum ampere rating of the overcurrent protective device and NOT by the size of the conductors used for the branch-circuit
True or False: Branch-circuit conductors shall have an allowable ampacity of NOT less than 125% of the continuous load, plus 100% of the non-continuous load to be served.
TRUE
When a single branch-circuit serves a continuous load of 20 amperes and a non-continuous load of 10 amperes, the branch-circuit conductors are required to have an allowable current-carrying capacity of at least _______.
- 00 amperes
- 50 amperes
- 00 amperes
- 50 amperes
=35.00 amperes
20 amperes x 1.25 = 25 amperes
10 amperes x 1.00 = 10 amperes
Total. = 35 amperes
True or False: Continuous load is a load where the minimum current is expected to continue for 3 hours or more
False: Continuous load is a load where the MAXIMUM current is expected to continue for 3 hours or more
True or False: Examples of continuous loads are lighting loads for commercial and industrial occupancies that are expected to be operated for at least three (3) hours
True
Examples of non-continuous loads are ….
General Purpose receptacle outlets provided for commercial, industrial, and residential occupancies and general.
Purpose lighting loads for RESIDENTIAL occupancies
When a 100 ampere rated circuit breaker is used to protect a branch circuit serving a continuous load, the load shall not exceed
80 amperes
100 amperes
125 amperes
115 amperes
=80 amperes
100 amperes x .80 = 80 amperes
Note* Overcurrent devices protecting branch circuits, are not to be loaded more than 80% of their rated value when protecting CONTINUOUS loads.
True or False: If the overcurrent device protecting the circuit is listed for continuous operations. It shall be permitted to have a rating of 100% of the continuous load(s) to be served. Circuit breakers are NOT listed for continuous operation, unless they have a rating of at least 400 amperes and more.
True
True or False: Lighting loads are to be suppled by 20 ampere rated branch circuits
False. Lighting loads are to be suppled by 15- AND 20 ampere rated branch circuits
How are lighting loads for specific occupancies determined?
Lighting loads are based on the unit load per square foot, depending upon the table (loads per occupancy)
How are GENERAL lighting loads to be calculated?
Lighting loads are to be calculated from the outside dimensions of the building.
How do you determine the area of a building to find the lighting load?
Square Foot, multiply the length of a building times the width of the building
A building has outside dimensions of 100 feet in length and 75 feet in width. The building has a total area of
750 sqft
175 sqft
7500 sqft
1750 sqft
=7500 sqft
100ft x 75 ft = 7500 sqft
How do you determine the area of a multi-story building?
Multiply the length of the building by the width of the building *** by the number of stories
A 3 story building having outside dimensions of 100ft by 75 ft has a total area of
2225 sqft
7,500 sqft
15,000 sqft
22,500 sqft
=22,500 sqft
100ft x 75ft x 3 (stories) = 22,500 sqft
When calculating lighting loads for dwelling units, do you include open porches, garages, or unfinished spaces not adaptable for future use?
No.
When calculating lighting loads for dwelling units, do you include garages?
No.
Are lighting loads of the habitable spaces of guest rooms of hotels and motels considered continuous?
No.
Are lighting loads of commercial and industrial occupancies considered continuous?
Yes.
What is the formula used to determine the minimum number of general lighting branch circuits required for a dwelling unit?
Number of Circuits = Load VA / Circuit VA
A dwelling unit having 2,000 sqft of habitable space is required to have a least ________ 15 ampere, 120 -volt general - purpose lighting branch - circuits.
2
3
4
5
=4
2000 sqft x 3 va / 120 volts x 15 amperes
6000VA/1800VA = 3.3 (4 circuits)
A multifamily condo, without cooking facilities provided for the tenets, having 12,000 sqft of living areas is required to have at least _________ 20 ampere, 120 volt general lighting branch-circuits, or at least ______15 ampere, 120 volt general lighting branch-circuits.
10-10
14-14
10-13
10-14
=10-14
12,000sqft x 2VA / 120volts x 20 amperes
24,000 VA / 2,400 VA = 10 circuits
12,000sqft x 2VA / 120volts x 15 amperes
24,000VA/1800VA =13.3 = 14 circuits
*Multifamily dwellings without cooking are calculated the same load Hotel and Motels (2VA)
What is the formula used to determine the minimum number of required general lighting branch-circuits for an office building, store, bank, restaurant, etc?
Number of circuits = load VA x 125% / circuit VA