Section 14 - Protection and Control Flashcards by Joe Locke

True or False?

The formula used to calculate the available short circuit current is:

True

This is the same as taking rated Secondary Current divided by %IZ as a decimal.

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A short circuit can be a ground fault or a line-to-line fault.

True or False

True

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An overload device and an overcurrent device are the same thing.

True or False?

False

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A 15A circuit breaker trips when a 20A current flows through it for around two minutes. This trip is most likely due to fault current.

True or False?

False

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Fuses used to protect against fault level overcurrents do not need an interrupting capacity rating.

True or False?

False

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It is possible to use a 60A Rated fuse holder for a 25A fuse.

True or False?

True, if Fuse Reducers are used.

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A dual-element fuse does not provide a time delay.

True or False?

False.

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A fuse may be responsive to overcurrents from both overloads, and _____ ________.

Short Curcuits

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A time delay fuse shall be marked with TD.

True or False?

False. 14-200 2)

The marking referred to in Subrule 1) shall be the letter “P” for low-melting-point types that do not have time-delay characteristics and the letter “D” for time-delay fuses.

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Plug fuses are limited to a maximum of 30A continuous current rating.

True or False?

True. 14-208 1)

Plug fuses shall be rated at not more than 30A.

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A Class H fuse has an interrupting capacity of

a) 10 000A
b) 50 000A
c) 100 000A
d) 200 000A

a) 10 000A

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A Class C fuse offers overload and short circuit protection.

True or False?

False. 14-212 c)

Class C and HRCII-MISC fuses shall be permitted to be used for overcurrent protection, only where circuit overload protection is provided by other means.

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A Class K fuse can replace a Class H fuse, and is often used to provide better interrupting capacity.

True or False?

True.

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A 250V fuse will fit a 600V fuse holder if approved fuse reducers are used.

True or False?

False.

Fuse reducers permit the use of lower ampere rated fuses to be used in higher ampere rated fuse holders.

Voltages are different so it won’t fit.

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A circuit breaker is a manual control device as well as an overcurrent device.

True or False?

True.

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The electromagnetic trip component of a circuit breaker reacts to:

a) Overloads
b) Short Circuits
c) Both Short Circuits & Overloads
d) Low-level Arc-Faults only

b) Short Circuits

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Protective devices are required to operate automatically under which two conditions?

Overcurrent
Ground Fault

14-010 a)
Electrical apparatus and ungrounded conductors shall be provided with…
a) devices for the purpose of automatically opening the electrical circuit thereto,
i) if the current reaches a value that will produce a dangerous temperature in the apparatus or conductor; and
ii) in the event of a ground fault, in accordance with rule 14–102

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The ungrounded conductors of a multi-wire circuit must have a manually operable control device that will disconnect all ungrounded conductors simultaneously with exceptions.

What are the exceptions?

-Multiwire branch circuits for lighting loads, non-split receptacles, and that have each lighting load or receptacle connected to the neutral, and one ungrounded, conductor, and devices that when necessary will open the electrical circuit there are two in the event of failure of voltage in such circuit.

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Which rule other than 14-100 1) permits the rating of an overcurrent device to exceed the allowable ampacity of a conductor?

14-104 1) a) b) c)

a) where a fuse or breaker having a rating or setting the same as the conductor is not available, values in table 13 shall be permitted up to 800A

b) flexible cord #16,18 and 20 copper and tinsel on 15A O/C

c) other rules in this code

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It is necessary for a portable commercial iron with a rating of 2500W to have an additional control device.

True or False?

True. 14-602 a)

If the appliance is over 1500W

Or…

If the appliance does not have a cord-end, plug or other means of readily disconnecting it, it needs an additional control device.

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What are the requirement for mounting a knife switch?

14-502 1) 2) 3)

1) ST KS’s shall be mounted with their bases in a vertical plane
2) ST KS’s shall be mounted so that gravity will not close them.
3) DT KS’s can be mounted vertically or horizontally as long as if vertically there is a “stop” or positive locking device to prevent gravity from throwing the switch.

When two single-pole breakers are used as a two pole breaker, what are the CEC requirements?

14-302 b)

Their handles are interlocked with a device as provide by the manufacturer so all ungrounded conductors open simultaneously.

Must be tied together with an approved tie handle.

What is the maximum Voltage to Ground rating for Plug Fuses?

150V

14-202

What is the maximum Current rating for Plug Fuses?

30A

14-208 1)

In a single-phase 3-wire system, how many individual lighting branch circuits can originate from a common enclosure without the overcurrent devices being contained in a panelboard?

2 individual lighting branch circuits. 14-110 1) a)

The network system is also referred to as a **ring** system. True or False?

True

Where do you normally see the **Network** system?

Downtown Cities

What makes the **ring** system different from the traditional **network** system?

The **ring** system is a closed loop network system.

What is a network system?

It is a type of utility distribution system. In a network system, transformers are connected in parallel on the secondary side, reducing the impedance of the supply system, and increasing the capacity. This allows a transformer to be isolated for maintenance while the other transformers in the network share the load that was on the transformer that is being worked on.

What is the **Radial System**?

It is the conventional utility distribution system. it’s used in residential and light commercial neighborhoods. Since it is a radial system, the service to any building is fed from only one transformer.

Is the maximum fault current relatively high or relatively low in a radial system and why?

Relatively low because the fault current is based on the impedance of one transformer.

Is the available fault current relatively high or relatively low in a network system and why?

Relatively high. Much higher than the radial system because the available fault current is calculated based on the total impedance of all the transformers in the network.

Where is the radial system usually used?

Residential and light commercial neighbourhoods.

A radial system typically has a much higher available fault current than a network system. True or False?

False.

A radial system is usually used in downtown cores. True or False?

False

A network system is usually used in a network of residential neighbourhoods. True or False?

False.

A contactor used to switch an inductive lighting load must have an ampere rating of twice the load ampere rating. True or False?

True. 14-508 d) d) for inductive loads, switches, shall have an ampere rating of twice the ampere rating of the load.

A 347V light switch may be installed in a two–gang box together with a 120V switch if there is a permanent barrier between the two. True or False?

True. 14-514

A manual, general-use switch controlling a 10A, 120V inductive load is required to have a 15A minimum ampere rating. True or False?

True. 14-510

In a proper selectively coordinated system, the overcurrent device that trips first will be the: a) Service b) Main c) Feeder d) Branch Circuit

d) Branch Circuit

You may install a circuit breaker that does **not** have an interrupting rating, equal or greater than the available fault current of the circuit if it is approved as part of a series-rated combination. True or False?

True. 14-104 a)

Ground fault circuit interrupter [GFCI] receptacles provide protection against line–to–line faults. True or False?

False.

Receptacles installed within 1.5m of kitchen sinks must be protected by Class A GFCIs. True or False? Rule?

True. 26-704

A Class A GFCI must be used to protect all receptacles that are located outdoors. True or False? Rule?

False. 26-704

An AFCI protects against series and parallel low–level arcing faults. True or False?

True.

In a three-phase 4-wire system, how many individual lighting branch circuits can originate from a common enclosure without the overcurrent devices being contained in a panelboard?

3 individual lighting branch circuits. 14-110 1) b)

What is the passive functionality of a fuse?

Carries normal load current continuously without deteriorating due to age or overheat.

What is the Active functionality of a fuse?

Open the circuit when under abnormal conditions.

What are the two ratings of an Overcurrent Device?

- Continuous Current Rating - Interrupting Rating

At its minimum, what percentage of a fuses continuous current rating is it’s interrupting rating?

130% if it’s continuous current rating.

For a Time-Delay Fuse, how long can it hold an overcurrent and how far over its continuous current rating?

500% of the continuous rating for approximately 10 seconds.

Class H fuses are often referred to as ______ fuses.

Code They are one time fuses but are also available as renewable where the element or link needs to be replaced.