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Michigan electrical contractors Journeyman
Electrician Practice Test with 100% correct
answers
Conductors with _____ marked on the insulation are NOT approved for use in a wet location. - correct answer ✔ 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? - correct answer ✔ 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 _____. - correct answer ✔ 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? - correct answer ✔ 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 _____. - correct answer ✔ 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 _____. - correct answer ✔ 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 conductors are installed in a conduit or tubing nipple of _____ or less in length, the ampacity adjustment factors for more than three (3) current-carrying conductors in the raceway, are not required to be applied. - correct answer ✔ 24 inches adjustment factors for more than three (3) current-carrying conductors in raceways shall not apply where the raceway is not more than 24 inches in length. Where more than 3 current-carrying conductors are installed in short lengths of conduit or tubing, the heating effect caused from the additional conductors is insignificant therefore, the allowable ampacity of the conductors is not greatly reduced. In compliance with the NEC, the total marked rating of a 120-volt, cord-and- plug-connected room air conditioner shall not exceed _____ of the rating of a branch circuit when lighting units, general-use receptacles, or other appliances are supplied from the branch circuit. - correct answer ✔ 50% the special provisions for room air conditioners which are (1) rated not over 250-volts ac, single-phase and (2) which are cord-and-attachment plug connected. In order to prevent overloading the branch circuit, as per 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? - correct answer ✔ 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. - correct answer ✔ 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 - correct answer ✔ Any of the above
Generally, in a movie theater the manual switch for controlling the emergency lighting systems is permitted to be located _____. - correct answer ✔ in an accessible location in the lobby apply buildings used as a theater or for a similar purpose. Section 520. mandates the control of emergency systems in theaters to comply with the rules set forth in Article 700; Part V of Article 700 applies to the control of emergency lighting circuits. Section 700.21 does not permit a manual control switch for emergency lighting to be placed in a motion picture projection booth or on a stage or platform; the switch shall be located in the lobby or at a convenient accessible location.Emergency lighting systems are designed and installed to maintain a specific degree of illumination for means of egress of the building in the event of fire, or similar emergency, or if the normal power supply fails. Single-conductor cable such as _____ and single-conductor cable listed and identified as solar photovoltaic (PV) wire are permitted for use in PV source circuits within the PV array. - correct answer ✔ USE- 690 covers the wiring methods specified for use on solar photovoltaic (PV) systems arrays. indicates open, single-conductors such as Type USE-2 and single-conductor cable listed and identified as PV wire are permitted foruse in PV source circuits within the PV array. These conductors are evaluated and listed for use where exposed to sunlight and wet conditions.
For dwelling units, GFCI protection is required for all single-phase, 125-volt, 15- and 20-ampere receptacles installed within six (6) feet of the top inside edge of the bowl of sinks located in _____. a. laundry rooms b. bathrooms c. garages d. all of these areas - correct answer ✔ 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. - correct answer ✔ 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 _____.
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? - correct answer ✔ 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 _____. a. must be Type NMC b. must be Type NMS c. must be Type NMW d. is prohibited - correct answer ✔ Is prohibited he inside of all raceways and enclosures located underground is classified as a wet location. The conductors and cables installed in underground installations must be of a type listed for use in wet locations.Restrictions of the use of non- metallic sheathed cable
NMC is permitted in dry, moist, and damp locations, but wet locations are not included in this list. According to the NEC, fixed outdoor deicing and snow melting equipment is to be considered as a _____ load. - correct answer ✔ Continuous a continuous load is a load expected to continue for three (3) hours or more.The installation requirements for fixed outdoor electric deicing and snow melting equipment, fixed outdoor electric deicing and snow melting equipment shall be considered a continuous load.When sizing conductors and overcurrent protection for the fixed outdoor equipment you must take into consideration the equipment can operate over 3 hours, so it is considered a continuous load. In regard to a commercial building, where a service-entrance conduit having a length of six (6) feet contains four (4) size 2 AWG THWN insulated copper current-carrying conductors, each of the conductors have an allowable ampacity of _____. - correct answer ✔ 92 amperers To solve this problem first locate the conductor size,and look under the copper THWN column with a temperature rating of 75°C and note the ampacity of the conductors is 115 amperes. The table is based on an ambient temperature of 86°C and not more than 3 current-carrying conductors in the raceway. 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
For stationary small motors rated less than .................., the branch circuit over current device may serve as a controller. - correct answer ✔ 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 - correct answer ✔ 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? - correct answer ✔ 40 amperes The rating of disconnecting means is 115% of full load current.34 * 1.15 = 39. 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? - correct answer ✔ 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? - correct answer ✔ 6 AWG THWN Copper FLI current of single phase 10 HP motor at 230 volts = 50 amperes Minimum conductor ampacity = 50 * 125% = 62.5 amperes 6 AWG THWN Copper with 65 amperes capacity at 75 0C is suitable conductor for the motor In a metal wire-ways, the distance between supports shall not exceed .............. ft. - correct answer ✔ 10 Underground wiring shall be installed in which of the following conduit a.)Threaded rigid metal b.)Threaded steal intermediate metal c.)All options are correct .)PVC - correct answer ✔ All options are correct What is the resistance of 80 watt Light bulb rated at 120 volts? - correct answer ✔ 180 ohms
Flexible cards may not be used in the following locations .......... - correct answer ✔ To replace a fixed wiring of a structure What is the minimum percentage rated voltage that a storage battery should supply the emergency load? - correct answer ✔ 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. - correct answer ✔ 15 The interior of any dip tank can be considered as ................... location - correct answer ✔ Class1, Division Should ungrounded ducts or conduits should be sealed before entering buildings? - correct answer ✔ 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. - correct answer ✔ 3
