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45 Cards in this Set
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"Concealed" as applied to electrical wiring means: |
Rendered inaccessible by the structure or finish of the building |
NEC Article 100 - Definitions |
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A feeder is: |
All circuit conductors between the service equipment, the source of a separately derived system, or other power supply source and final branch-circuit overcurrent device. |
NEC Article 100 - Definitions |
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A bonding conductor or jumper is: |
A reliable conductor to ensure the required electrical conductivity between metal parts required to be electrically connected |
NEC Article 100 - Definitions |
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In locations where electric equipment would be exposed to physical damage, the following must be provided: |
Enclosures or guards |
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To provide access to the working space about electric equipment, the following number of entrancesof sufficient size must be provided: |
1 |
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Externally operable means: |
Capable of being operated without exposing the operator to contact with live parts |
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What must be provided for in all working spaces above service equipment? |
Illumination |
NEC Section 110.26(D) Such lighting shall not be controlled by automatic means only. |
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Parts of electric equipment that in ordinary operation produce arcs, sparks, flames, or molten metal shall be enclosed or separated and isolated from: |
All combustible material |
NEC Section 110.18 |
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Working space in rooms containing electrical equipment shall not be used for: |
Storage |
NEC Section 110.26(B) |
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In all cases where there are live parts normally exposed on the front of switchboards or motor control centers, the working space in front of such equipment shall not be less than: |
3 feet |
NEC Table 110.26(A)(1) 600 volts or under. To keep a safe distance from live electrical parts. |
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Ampacity is defined as: |
The maximum current, in amperes, that a conductor can carry continuously under the conditions of use without exceeding its temperature rating |
NEC Article 100 - Definitions |
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"Approved" as used in the NEC means: |
Acceptable to the authority having jurisdiction |
NEC Article 100 - Definitions |
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Which of the follow anchors may not be used to secure electrical equipment to masonary walls? |
Wooden plugs driven into holes in the masonry for holding wood screws. |
NEC Section 110.13(A). |
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A device designed to open and close a circuit by nonautomatic means and to open the circuit automatically on a predetermined overcurrent without damage to itself when properly applied within its rating is called a: |
Circuit breaker |
NEC Article 100 - Definitions |
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A separate portion of a conduit or tubing system that provides access through a removable cover(s) to the interior of the system at a junction of two or more sections of the system or at a terminal point of the systemis defined as a: |
Conduit body |
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What device is now required to detect and protect against arcing in 15- and 20-amp branch circuits supplying outlets installed in dwelling units? |
AFCI |
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Which circuits must not be connected to any system containing trolley wires with a ground return? |
Circuits for lighting and power |
NEC Section 110.19 |
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The minimum headroom of working spaces about service equipment, swithboards, panelboards, or motor control centers shall be at least : |
6 1/2 feet |
NEC Section 110.26(A)(3). Measurment is taken from floor to ceiling ; not from the top of the panelboard. |
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Indoor electrical installations over 600 volts that are open to unquilified persons shall be made with: |
Metal-enclosed equipment |
NEC Section 110.31(B)(1) |
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The entrance provided to give access to the working space about electric equipment rated over 600 volts must not be less than: |
2 feet x 6 1/2 feet |
NEC Section 110.33(A)(3). Additionally, door(s) shall open in the direction of egress and be equipped with listed panic hardware. |
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Where switches, or other equipment operating at 600 volts, nominal, or less, are installed in a room or enclosure where there are exposed energized parts or wiring operating at over 600 volts, the high-voltage equipment shall be effectively separated from the space occupied by the low voltage equipment by a suitable : |
Partition, fence or screen |
NEC Section 110.34 (B) |
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A contact device installed at the outlet for the connection of an attachment plug is called: |
A receptacle |
NEC Article 100 - Definitions |
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The circuit in Figure 2-2 shows the resistors R2 and R3 connected in parallel, but resistor R1 is in series with both the battery and the parallel combination of R2 and R3. What is the total resistance of R2 and R3? |
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If the total combined resistance of R2 and R3 is 10 ohms, what is the total resistance of the entire circuit in Figure 2-2? |
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Assuming the battery in Figure 2-2 is 30 volts, what is the total current in the circuit? |
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According to Kirchhoff's voltage law, which of the following Ohm's law equations may be used to find voltage drip across a resistor? |
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A 120-volt circuit has an electric heater connected with a current rating of 7.5 amperes. What is the resistance in ohms of the connected pure resistance load? |
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An ohmmeter shows the resistance of a 240-volt electric heater to be 19.5 ohms. What current flows through this heater? |
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An incandescent lamp has a resistance of 104 ohms when 2 amperes of current flow. What is the voltage. |
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What current is drawn by a 277-volt fluorescent lamp with 8 ohms reactance? |
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If the impedance Z of the circuit impedance triangle in Figure 2-3 is 5 ohms and angle A is 30°, what is the value of the inductive reactance (XL)? |
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What is the minimum general lighting load permitted by the NEC in a 4500 square foot warehouse |
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What is the minimum general lighting load permitted in a 1500 square foot single family dwelling as specified in Table 220.12 of the NEC? |
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The voltage per turn for a transformer is 1.25 volts. What is the voltage of the transformer if it had 192 turns? |
192 X 1.25 = 240 volts |
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A 50 kVA, three-phase, delta-to-wye connected, 480/120-208 volt transformer is used to supply a lighting load. What is the rated phase current on the primary side? |
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A 50 kVA, three-phase, delta-to-wye connected 480/120-208 volt transformer used to supply a balanced lighting load will have what line-current rating on the secondary? |
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A 480/277 volt, Y-connected transformer is used to supply a balanced 277-volt, single-phase lighting load of 40,000 watts. What size transformer (kVA) should be used? |
40 kVA |
A watt is a watt, is a watt... |
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What is the maximum allowable wattage that can be connected to a 240-volt, 20-ampere,single-phase circuit feeding residential electric heaters? |
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An electric oven is rated at 2000 watts when connected to a 460-volt circuit. What is the resistance of the heating element? |
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What is the approximate wattage of a 240-volt motor with the resistance of 28 ohms? |
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The minimum allowable number of 120-volt, 15-ampere, 2-wire lighting branch circuits required for a residence 70 feet by 30 feet are: |
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A voltage drop of 3 volts has been determined on a 120-volt circuit. What percent is the voltage drop? |
2.5% |
3/120 = .025 or 2.5% |
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A voltage drop of 19.2 volts has been determined on a 480-volt circuit. What percent is the voltage drop? |
4% |
19.2/480 = .04 or 4% |
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If a 120-volt circuit feeds six 80-watt fluorescent lamps, what current is drawn if the power factor is 0.91? |
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Calculate the minimum volt-ampere capacity of a 155,000 square foot school. |
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