Journeyman theory 2024

Providing a path to earth often helps reduce electro static charge. True Lightning frequently terminates to a point of elevation and strikes non-metallic as well as metallic objects with the same frequency. True The termination of the lightning strike is unlikely to ignite combustible materials. False Lightning protection is intended to protect the building itself as well as the electrical equipment on or inside the structure. False Non-magnetic metals are ferrous meaning they do not contain any iron and cannot be magnetized. False Magnetic lines of force can cross each other and they are called flux lines. False It is not the force of the magnetic field through a conductor that produces electricity, it is the relative motion of the field to the electrons within the conductor that produces the movement of electrons. True People become injured in death occurs when voltage pushes electrons through the human body causing the heart to go into ventricular fibrillation. True The severity of an electric shock is dependent on the current flowing through the body, which is impacted by circuit voltage and contact resistance. True An electrical arc glass can approach______, which vapor rises metal parts and produces both in deadly pressure waves. 30,000°F If a conductor carrying current is next to another conductor carrying current in the opposite direction, the electromagnetic field attempts to push the conductors apart. True A clamp on a CM meter has a coil that is clamped around the conductor and detects the rising and falling______field being produced due to the arc flow through the conductor. Magnetic Ohmmeters measure the______or opposition to current flow of a circuit or component. Resistance The Megger is used to measure a very high______values, such as those found in cable insulation, or motor and transformer windings. Resistance The electric motor works on the principle of the attracting and repelling forces of______fields. Magnetic The______of a generator is forced to rotate while it is being subjected to the magnetic field of the stator. Rotor A holding relay is primarily use for work or convenience. False According to the electron current flow theory electrons flow away from the negative terminal of the source through the circuit and load, toward the positive terminal of the source. True According to the conventional current flow theory, electrons travel from the positive to negative. Trail The major advantage of a AC over DC is the ease of voltage regulation by the use of a transformer. True The best conductors, in order of the conductivity, are gold, silver, copper, and aluminum. False In a DC circuit, the only opposition to current flow is the physical resistance of the material. This opposition is called reactance and is measured in ohms. False What is the voltage drop of 2 12 AWG conductors (.40 ohms) supplying a 16 amp load, located 100 feet from the power supply? Formula Evd = I X R 6.4 volts What is the resistance of the circuit conductors when the conductor voltage drop is 7.20 V and the current flow is 50 A? R= E/I .14 ohms What is the power loss in watts of a conductor that carries 24 A and has a voltage drop of 7.20 V? 175 watts, P= IxE The formulas in the formula will apply to______ AC with unity power factor The opposition to current flow results in Voltage Drop. True Kerchoff's voltage law states, in a series circuit, the sum of the voltage drops across all of the resistors will equal the applied voltage. True Kerchoff's current law states, in a series circuit, the current is______through the transformer, the conductors, and the appliance. The same According to Kerchoff's current law, the total current provided by the source to a parallel circuit will equal the sum of the currents of all of the branches. True The total resistance of a parallel circuit can be calculated by______method. Equal resistance, product over sum, reciprocal. When power supplies are connected in parallel, the voltage remains the same, but the current or amp hour capacity will be increased. True A balanced three wire, 120/240 V, single phase circuit is connected so that the ungrounded conductors are from different transformer phases line 1 and line 2. The current on the neutral conductor will be______% of the ungrounded conductor current. 0% If the ungrounded conductors of a multiwire circuit Are not terminated to different phases, this can cause the neutral current to be in excess of the neutral conductor rating. True The current flowing on the neutral conductor of a multi wire circuit is called unbalance current. True Improper wiring or miss handling of multi wire branch circuits can cause______connected to the circuit. Overloading of the ungrounded conductors, overloading of the neutral conductors. Because of the dangers associated with an open neutral conductor, the continuity of the______conductor cannot be dependent upon the receptacle. Grounded Electrons leaving a power supply are always trying to return to the same power supply; they are not trying to go into the earth. True To prevent fires and electric shock, the NEC specifies that neutral current can flow on metal parts of the electrical system. False Metal parts of premises wiring must be bonded to a low impedance path designed so that the circuit protection device will quickly open and clear a ground fault. True Because of the earths______resistance to current flow, it cannot be used for the purpose of clearing a line to case ground fault. High The purpose of overcurrent protection is to protect the conductors and equipment against excessive or dangerous temperatures because of overcurrent. Overcurrent is current in excess of the rated current of equipment or conductors. it may result from an______. Overload, short circuit, ground fault. To protect against electric shock or to prevent a fire, a dangerous______must quickly be removed by opening the circuits overcurrent protection device. Overload, short circuit, ground fault. Inverse time breakers operate on the principal That as the current decreases, the time it takes for the device to open decreases. False The______Sensing element causes the circuit breaker to open when a predetermined calibration temperature is reached. Thermo The magnetic time delay circuit breaker operates on the solenoid principle where a movable core, held with a spring, is moved by the magnetic field of An ______. Short circuit, ground fault. Available short circuit current is the current in amperes available at a given point in the electrical system. True Factors that affect the available short circuit current include transformer______. Voltage, KVA rating, impedance.