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Journeyman Electrician Practice questions and answers test Conductors with _____ marked on the insulation are NOT approved for use in a wet location. - THHN conductors with THHN insulation are approved for use in dry and damp locations only and conductors with THWN, THHW, and THW insulation are recognized for use in dry and wet locations. Given: A one-family dwelling unit with a demand load of 200 amperes is supplied with a 120/240 volt, single-phase, electrical system from the local utility company. What is the MINIMUM size aluminum THW conductors required for use as service-entrance conductors for this residence? - 4/0 AWG one-family dwelling 120/240 volt, single-phase, service-entrance conductors to be sized at an ampacity of not less than 83% of the service rating. Therefore, 200 amperes x 83% = 166 amperes; size 4/0 AWG THW aluminum conductors with an allowable ampacity of 180 amperes should be selected for this dwelling. Where a 150 kVA, single-phase transformer having a secondary voltage of 120/240 is installed at a multi-family dwelling, the full-load current rating, in amperes, of the secondary is _____. - 625 amperes To find the full-load current rating of the single-phase transformer apply the single-phase current formula as shown:I = (150 kVA x 1000) / 240 volts = 15,000/240 = 625 amperes Which one of the following listed circuit breakers is NOT a standard ampere rating? - 75 amperes the standard ampere ratings for fuses and circuit breakers. A circuit breaker with an ampere rating of 75 amperes is not a standard ampere rating.
The MINIMUM length of free conductor to be left at each junction box for the purpose of splicing conductors, or making connections to illuminares or devices shall be _____. - 6 inches free conductor is to be left at each junction box for splices or the connection of luminaires or devices. The intent of this rule is to ensure enough conductor slack for the terminal connections or splices to be made easily. In general, overhead service-drop conductors shall NOT be smaller than _____. - 8 AWG copper overhead service-drop conductors to be not smaller than 8 AWG copper or 6 AWG aluminum or copper-clad aluminum. Do not get service-drop conductors, the overhead conductors between the utility electric supply system and the service point, confused with the service-entrance conductors, the conductors from the service point from the utility company to the service disconnecting means. When a galvanized eye-bolt is to be used as the point of attachment for an electrical service, the NEC requires the eye-bolt to be installed NOT less than _____ above finished grade. - 10 ft. provide adequate vertical clearance of the conductors and prevent physical damage to the conductors and prevent persons from making accidental contact with the conductors which may create a shock hazard or electrocution. In no case shall the point of attachment of the service- drop conductors to be less than 10 ft. above finished grade. Why is electrical continuity required for metallic conduit? - To establish an effective ground-fault path and facilitate the operation of the over-current protective device.
Section 40.62(C), the total rating of the A/C unit shall not exceed 50% of the rating of a branch circuit where lighting units, general-use receptacles or appliances are also supplied. What shall not be located over the steps of a stairway? - overcurrent devices "overcurrent devices shall not be located over steps of a stairway." This requirement address a serious safety issue. No one should be required to stand on different treads on a stairway to replace, repair, maintain, install, troubleshoot, or reset overcurrent devices in a panelboard or switchboard located in a stairway. Where a permanently installed outdoor swimming pool is located on residential or commercial properties, at least one (1) single-phase, 125- volt, 15- or 20-ampere receptacle shall be located not less than _____ from and not more than _____ from the inside wall of the swimming pool. - 6 feet - 20 feet apply to the installation of wiring methods and equipment in or adjacent to permanently installed swimming pools. each permanently installed swimming pool is to be provided with at least one (1) single-phase, 15- or 20-ampere, 125-volt, receptacle placed not closer than six (6) feet from the pool and not more than twenty (20) feet from the pool. This requirement allows ordinary appliances such as a radio, to be safely plugged in and used near the pool, but avoids the need for extension cords in the pool vicinity. Be advised the receptacles must be provided with Metal water pipes installed in or attached to a building or structure shall be bonded to _____.
a. the service equipment enclosure b. the grounded conductor at the service c. the grounding electrode conductor d. any of the above - Any of the above requires metal water piping systems to be bonded to any of (1) the service entrance enclosure, (2) the grounded conductor at the service, (3) the grounding electrode conductor.Where mechanical and electrical connections are within equipment, a failure of electrical insulation can result in the connected piping systems becoming energized. For example, an insulation failure in an electrical circuit of a water heater could energize the metal water piping.Metal water piping systems must be bonded so that when a fault occurs between an ungrounded (hot) conductor and the piping, the potential difference between the two is minimized, thereby reducing the risk of electrical shock.Also, note where installed in or attached to a building or structure, all metal piping systems, including gas piping, that is likely to become energized shall be bonded to a grounded source. When armored cable, Type AC, is installed in an accessible attic and is run parallel to the sides of rafters, studs, or floor joists, _____. a. the cable shall be protected with running boards b. the cable shall be protected by guard strips at least as high as the cable c. either A or B d. neither guard strips nor running boards shall be required - neither guard strips nor running boards shall be required where the armored cable is installed parallel to the sides of rafters, studs or floor joists, neither guard strips nor running boards shall be required to protect the cable in accessible attics. if the cables run across the top of the floor joists in an attic that is not accessible by permanent studs or ladders, protection of the cable is
a. laundry rooms b. bathrooms c. garages d. all of these areas - All of these areas no matter what the location or room in a dwelling, where the 15- or 20- ampere, 125-volt eceptacles are installed within six (6) feet from the top inside edge of the bowl of the sink, GFCI protection must be provided to prevent a ground-fault shock hazard. For a building or structure where the meter enclosure is adjacent to the service disconnecting means, it is permitted to ground the meter enclosure to the _____ conductor on the load side of the service disconnect if ground-fault protection is not provided. - Grounded The meter enclosure to be grounded by connection on the load side of the service disconnect where (1) no ground-fault protection is installed, (2) the meter enclosure is adjacent to the service disconnecting means, and (3) the grounded service conductor is not smaller than the size specified In a dwelling unit where a 125-volt, 15- or 20-ampere receptacle is located under the counter for an in-sink waste disposer, the receptacle must be provided with _____. a. AFCI protection only b. GFCI protection only c. both AFCI and GFCI protection d. neither AFCI nor GFCI protection - Both AFCI and GFCI protection Because of the presence of water and grounded surfaces that contributes to a potential shock hazard
any 125-volt, 15- or 20-ampere receptacle installed within six (6) feet of a sink is required to be GFCI protected. Section 210.12(A) verifies AFCI protection is required for all 120-volt, 15- or 20-ampere branch-circuits that supply outlets in kitchens in dwellings.AFCI devices are designed to determine resistance to unwanted tripping due to the presence of arcing that occurs in utilization equipment under normal operating conditions or to a loading condition that closely mimics an arcing fault. Where a 125-volt, 15-ampere receptacle is connected to a 120-volt branch circuit supplying two (2) or more receptacles or outlets, the maximum permitted cord-and-plug-connected load to the receptacle is _____. - 12 amperes the general rules regarding branch circuits. Branch circuit and receptacle ratings are addressed in Part II of Article 210. To prevent overheating receptacles, a receptacle shall not supply a total cord-and-plug-connected load in excess of the maximum specified in Table 21(B)(2), where connected to a branch circuit supplying multiple receptables or other outlets. This table shows a 15-ampere rated receptacle may carry a maximum cord-and-plug-connected load of 12 amperes under this condition. In industrial establishments only, when a 200-ampere rated busway is tapped from a 600-ampere rated busway, what is the maximum permitted length of the 200-ampere busway where overcurrent protection is not provided for the 200-ampere busway? - 50 ft the permitted installation of busways. For busways in industrial establishments only, providing overcurrent protection at the point where the busway size is changed is not required if the busway having the smaller ampacity does not exceed fifty (50) feet in length and has an ampacity of at least one-third the rating of the overcurrent protection of the larger usway. 1/3 of 600 amperes = 200 amperes When installing nonmetallic sheathed cable enclosed in an underground buried PVC conduit, the cable _____.
in this situation there are 4 current-carrying conductors in the raceway therefore, we must apply the correct adjustment factor (derating value) 2 AWG THWN ampacity = 115 amperes (before derating)115 amperes x 80% (adjustment factor) = 92 amperes What material should not be used for Grounding electrodes. - Aluminum For a 300 ampere electrical circuit, what is the minimum size copper equipment grounding conductor as per NEC? - 4 awg 4 AWG is the minimum size wire for a 300 ampere circuit What is the minimum size secondary conductor required for a 2 wire 480 volts/ 120 volts transformer rated at 2.3 KVA with 750C temperature at terminals? - 14 AWG Secondary transformer current = 2300 / 120 = 19.16 amperes The suitable conductor is 14 AWG with 20 amperes capacity at 750C What is the resistance of the conductor if the conductor voltage drop is 3.6 volts and current flowing through conductor is 18 amperes? - 0.2 ohms Conductor voltage drop = 3.6 volts I R = 3.6 volts R = 3.6 / 18 = 0.2 ohms When an electrical circuit tested with ohmmeter, a short circuit is indicated by a reading of ...................... - Zero
For stationary small motors rated less than .................., the branch circuit over current device may serve as a controller. - 1/ 8 horse power What is the demand factor applied in calculating feeder or service conductor load for a commercial kitchen having four electrical equipment - 80 % Demand factor for kitchen equipment in other than dwelling unit shall be applied according to 220.56 table. A 440 volts motor has a full load current of 34 amperes. what size disconnecting means is required? - 40 amperes The rating of disconnecting means is 115% of full load current.34 * 1.15 = 39.1 amperes.The nearer rating is 40 amperes. If two 4 ohm resistors are connected in series which are powered by 240 volts power source, what is the current flow across one 4 ohm resistor? - 30 amperes Total resistance of the circuit = 4 + 4 = 8 ohms Current flow in the circuit = 240 /8 = 30 amperes In series circuit flow in the circuit elements is same. so 30 amperes current will flow in both series resistors. What is the minimum size of THWN conductors required for single phase 10 HP motor connected to 240 volts supply? - 6 AWG THWN Copper FLI current of single phase 10 HP motor at 230 volts = 50 amperes
If a 230 volts load is connected to 240 volts power source, what is the minimum voltage that can be supplied to load as recommended by NEC? - 228 volts When the single phase air conditioner rating is less than .......... at 240 volts can be considered as single motor unit in determining branch circuit conditions. - 40 amperes What is the low voltage contact limit for sinusoidal AC? - 15 Volts RMS Flexible cards may not be used in the following locations .......... - To replace a fixed wiring of a structure What is the minimum percentage rated voltage that a storage battery should supply the emergency load? - 87 1/2 % The vertically run metal wire-ways shall be surely supported at intervals not exceeding ............. ft of wire way and shall not have more than one joint between supports. - 15 The interior of any dip tank can be considered as ................... location - Class1, Division Should ungrounded ducts or conduits should be sealed before entering buildings? - yes, to prevent unwanted gases entry in buildings A continuous load is load where the maximum current is expected to continue for ............ hours or more. - 3
