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78 Cards in this Set
- Front
- Back
The electrical service supplied to a Building is measured in what units? |
Amperes |
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An electrical distribution system consists of what five things? |
1- an electric meter 2- a main switch or breaker 3- a distribution panel 4- fuses or circuit breakers 5- wire conductors |
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What device would protect users of electrical equipment from shock hazards in damp conditions? |
A ground fault circuit interrupter (GFCI) |
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Once a GFCI receptacle get tripped, can it be reset without going to the distribution panel? |
Yes |
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“Permanently joining all non-current-carrying metal parts to ensure electrical continuity” is a partial definition of? |
Bonding |
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What size conductor is required to bond gas piping systems to the buildings electrical system grounding conductor? |
#6 AWG (or larger) copper |
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The two most common devices for the protection of electrical systems are what? |
1- fuses 2- circuit breakers |
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Where would maximum ampacity values for over current protection devices be specified? |
Canadian electric code, part 1 |
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Two situations that cause overcurrent are? |
1- a surge in current when a motor starts up 2- a short circuit |
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An electrical overload happens very quickly. True or false? |
False |
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What advantage does a circuit breaker have over a fuse? |
It can be reset instead of having to be replaced. |
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What is the most common electrical conductor? |
Wire |
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The two basic types of wire are? |
Solid wire and stranded wire |
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The maximum current rating of a #10 AWG conductor is less then that of a #14 AWG conductor. True or false? |
False |
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Where the possibility of physical damage to a conductor exists, what must be done? |
The conductor must be adequately protected |
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Electrical distribution, in a building, consists of? |
1- the device equipment 2- the branch circuits |
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Low-voltage circuits operated at what voltage? |
31V to 750V, inclusive |
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What type of armoured cable should be used for installations subject to adverse service conditions? |
Teck |
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What is the purpose of ladder and schematic diagrams? |
To show how circuits work and the function of their components |
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How are components represented on connection diagrams? |
By symbols |
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Gas technicians should have a thorough understanding of electrical symbols. True or false? |
True |
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The sequence of operation of a circuit can be determined from what kind of drawing? |
A schematic diagram |
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What type of diagram is most helpful when trying to trace wires? |
A wiring diagram |
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In which position will the switch’s and other devices in a circuit be shown in if a wiring diagram is drawn in the “at rest” state? |
In their normal positions (normally-open or normally-closed, depending on their function) |
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In which position will the switch’s and other devices in a circuit be shown in if a wiring diagram is drawn in the “at rest” state? |
In their normal positions (normally-open or normally-closed, depending on their function) |
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All control valves open and close in response to changes in what? |
Temperature, pressure, humidity and fluid flow |
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A multimeter incorporates which basic electrical meters? |
1- voltmeter and millivoltmeter 2- ammeter 3- ohmmeter |
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An ammeter is connected in parallel with the circuit under test. True or false? |
False |
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A continuity check is actually a measurement of what? |
Resistance |
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A continuity check is actually a measurement of what? |
Resistance |
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An ohmmeter should always be connected to a live circuit. True or false? |
False |
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A continuity check is actually a measurement of what? |
Resistance |
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An ohmmeter should always be connected to a live circuit. True or false? |
False |
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Is it advisable to test a fan circuit with a multimeter? |
Yes |
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How many wires are contained in a service conductor to a residential distribution panel and what are they? |
1- four 2- two hot wires, one neutral and one ground wire |
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Where do branch circuits start? |
At the distribution panel |
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Where do branch circuits start? |
At the distribution panel |
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All line voltage circuits have a continuous ground from the distribution panel to where? |
Each junction box, receptacle and appliance |
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How are transformers rated? |
By the amount of power the secondary winding can handle |
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How are transformers rated? |
By the amount of power the secondary winding can handle |
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All electrical connections shall be made where? |
In outlet or junction boxes |
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Bonding conductors must be soldered. True or false? |
False |
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Switches are always located in the hot leg of a circuit. True or false? |
True |
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Switch’s must be in what position to conduct electrical current? |
Closed |
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Switch’s must be in what position to conduct electrical current? |
Closed |
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Switch’s are operated by hand or by? |
1- changes in pressure 2- changes in fluid flow 3- changes in temperature |
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Switch’s must be in what position to conduct electrical current? |
Closed |
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Switch’s are operated by hand or by? |
1- changes in pressure 2- changes in fluid flow 3- changes in temperature |
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Despite their similarity in outward appearance to the contacts in a light switch, how are the contacts in a toggle motor starter different? |
The contacts in a toggle motor-starter are horsepower rated and the contacts in a light switch are rated for the amount of current they can handle. |
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Relays are magnetically operated to which principle? |
The solenoid principle |
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Control relays are best suited for controlling single-phase pumps of any size. True of false? |
False |
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How does a contactor differ from a relay? |
A contactor has large-load contacts so it could handle large amounts of current |
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What is meant by the term “gangable box”? |
Several boxes may be joined or “ganged” together |
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List some common fasteners used for securing electrical cable and conduit. |
Staples, clamps, cleats, sleeves, straps and grommets |
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The point at which two to similar metals are joined on a thermocouple is known as what? |
The hot junction |
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Thermocouples are used with which type of pilot? |
A constant (standing) pilot |
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What does a thermocouple power when it I being heated? |
The electromagnet in the safety shut-off or safety switch. |
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What does a thermocouple power when it I being heated? |
The electromagnet in the safety shut-off or safety switch. |
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Approximately how many thermocouples does a power pile contain and how are they connected? |
10 to 30, connected in series |
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What portion of the hot junction should be heated by the pilot flame and what should the temperature difference be between the hot and cold junctions? |
1- the first 0.375 to 0.5 inches of the tip 2- at least 400f (204c) |
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What are powerpiles with outputs of 250 to 750 mv able to power? |
An appliance combustion safety circuit and its control circuit |
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Upon inspection, the pilot flame of a powerpile-equipped appliance is observed to be blue in colour, burning steadily and contacting the top .5 inch of the powerpile tip. Is this acceptable? |
Yes |
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Three things that can cause a small, blue pilot flame? |
1- a small or restricted orifice 2- low gas pressure 3- a clogged pilot filter |
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Is an external power source required for a control circuit operating on a thermopile millivoltage? |
No |
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What type of current do thermocouples and thermopiles produce? |
DC current |
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Ha type of test is preformed to check the polarity of a millivolt meter? |
A flash test |
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Ha type of test is preformed to check the polarity of a millivolt meter? |
A flash test |
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A thermocouple must be under load to preform an open circuit test. True or false? |
False |
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What does a closed-circuit test show? |
Millivoltage that can be maintained under load |
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During the pilotstat coil test, at what point and at what mv reading should the coil drop out? |
- within 90 seconds - between 2 mv and 5 mv |
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Excessive millivolt drop indicates excessive resistance. what is the cause of the resistance? |
Loose wire connections, poor wire splices, excessive wire run length, corroded terminals and connecters |
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The three available thermal pile outputs are? |
250 mV, 500 mV and 50 mV |
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A 750 mV powerpile should be used when? |
When there is a need to power two circuits |
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Testing a 750 mV circuit is essentially the same as testing a 500 mV circuit, except for what? |
The steps for testing the pilotstat coil |
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The voltage rating of a Milli volt thermostat is? |
0 to1.5 V DC |
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Total electrical resistance in the system includes the heat anticipator in the thermostat. true or false? |
True |
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Name three components of a self powered heating control system. |
A- pilot burner B- thermal pile C- diaphragm gas valve D- limit switch E- Milli volt thermostat F wire runs for connecting the devices in the system |
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The manufacturer recommends maximum lengths of wiring runs for self-powered control systems. true or false? |
True |