Commercial Wiring Ch.6-10

What are the two methods for providing floor outlets?

1. Installing underfloor raceway or 2. Installing floor boxes

When selecting the conductor type for a feeder, if the selected OCPD has a rating greater than ________, the conductors to be installed are selected from either the ___degrees C or ____ degrees C column of NEC table 310.15(B)(16)

100 amperes; 75; 90

NEMA rated motors are designed to operate at +/- ____% of their __________ rated voltage.

10; nameplate

What kind of raceways are used to connect recessed or lay-in luminaires? What do electricians refer to this as?

Flexible metal and nonmetallic conduit ; fixture whip

What are the three features are available with receptacles for multioutlet assemblies?

GFCI, isolated ground, surge suppression

What has a smooth seamless inner core and cover bonded together and having one or more reinforcement layers between the core and covers for a layered conduit?

LFNC-A

What is LFNC?

Liquidtight Flexible Nonmetallic Conduit

Floor boxes, either metallic or nonmetallic, can be wired using any *suitable* raceway, such as a, b, c, d.

Metallic and Non-Metallic Rigid Conduit, and Metallic and Non-Metallic Electrical Tubing.

What are the two most popular types of PVC?

Schedule 40 & Schedule 80

Which has a thicker wall, Schedule 40 or Schedule 80 PVC?

Schedule 80

What does 430.24 apply to?

The ampacity of conductors that are supplying several motors, or a motor(s) and other load(s).

True or False: Schedule 40 and Schedule 80 PVC are permitted underground (direct burial or encased in concrete) and aboveground (indoors and outdoors) exposed to sunlight.

True

What is the most common cause of motor failure?

Unbalanced voltage which causes unbalanced currents in the motor's stator windings.

What allows a motor to start,yet opens on an overload before the motor is damaged?

a dual-element, time delay fuse.

To get accurate current readings where harmonics are involved, _______, referred to as "_______" must be used.

ammeters; true rms

How is a raceway defined by the NEC?

as a channel that is designed and used expressly for the purpose of holding wires, cables, or busbars. (Art. 100)

A reception area is provided with a ____________ system to provide a different "look" for the clients.

combination lighting system

Because the circuit breaker for the water heater is located in the panelboard on the 2nd floor, and is out of sight from the water heater, a __________ at the water heater is required by 422.31(B)

disconnecting means

The electrical contractor will install a ______ conduit system according to the specifications for the commercial building and in the locations indicated on the working drawings for the communications systems.

empty

The requirements of 310.10 (H) for parallel conductors are to ensure the conductors will share the current ______ to prevent _____ individual conductors.

equally; overloading

In the insurance office, a special raceway is installed in the two _______ walls. This raceway provides for both __________ and _______.

exterior; electrical power and communications

Ungrounded "hot" conductors can be just about any color except _____, _____, _______, or any color conductor (except green) that has three continuous _______ ___________.

green, white, gray, white stripes. 200.7(A)

Regarding the basement communication wiring: The inside conduit drops need not be _______ unless they can become ________. 250.86, Exception 2

grounded; energized

For the computer room special receptacles, the _______ terminal of each of these receptacles is connected to an _________ conductor and not to the ______.

grounding; insulated equipment grounding conductor; box

_______ are multiples of a fundamental frequency.

harmonics

If the ampacity of a feeder does not match a standard OCPD rating, then the next *lower/higher* rating may be used, provided the rating is ______ amperes or less. 240.4(B)

higher; 800

If voltage drop is a problem, it can mean an ________ in size of the ____________and/or_____________.

increase; conductor and/or raceway

Some boxes must be installed to the correct height by adjusting the __________________ before the concrete is poured.

leveling screws

The surge protection feature of the receptacles provides protection from ______ and other __________________ that may occur in the electrical system.

lightening; severe electrical surges

NEC 310.10 (H) sets forth the requirements for installing __________.

parallel conductors

The compression fittings for EMT are classified as ______ tight and _______ tight types.

raintight; concrete-tight

What is temperature rise?

the difference between motor winding temperature and the ambient temperature.

Who is responsible for installing an empty conduit system according to the specifications for the commercial building and in the locations indicated on the __________ drawings?

the electrical contractor; working

Water heaters are available for commercial occupancies in many sizes and ______, and for both single and _______ supply.

voltages; single and 3-phase

Because of ______ and ______ factors, Aluminum is frequently selected for ________ and _________.

weight and cost; feeders and services

Why does the Code use the term motor location instead of motor?

Because in many instances, the motor is inside an enclosure and is out of site until an access panel is removed.

How is the thickness of the wall of E.M.T. described?

It's a thin-wall metal raceway

Which PVC is allowed to be aboveground where subject to physical damage? and which is not?

Schedule 80 can be aboveground where subject to physical damage; Schedule 40 is NOT permitted to be aboveground where subject to physical damage.

Feeders are the part of the electrical system that connect the ________ to the __________.

branch-circuit panelboards to the elctrical service equipment.

For most applications, the motor circuit switch for a motor must be _______ rated.

horsepower

In surface metal raceways, conductors that are to be installed in raceways may be spliced at _________ or _____________ if the cover of the raceway is ______.

junction boxes; within the raceway;removable

Temperature rise means the difference between ____________ temperature and the ______ temperature.

motor winding; ambient

________________assemblies are similar to surface raceways and are designed to hold both ______ and _______.

multioutlet; conductors & devices

Simply stated, a motor may be loaded continuously up to the horsepower obtained by multiplying the rated _______ by the _______.

multiplying the rated horsepower by the service factor.

When calculating the size of a feeder, only the larger of any *coincident/noncoincident* loads such as air-conditioning and heating need to be included. NEC 220.60

non-coincident

Surge protectors are available in _______ units, which can be used to provide protection on any type of sensitive equipment such as __________ and __________.

separate; computers; printers

Unbalanced voltage causes _____________ in the motor's ___________.

unbalanced currents; stator windings

You should take special note of long runs of raceway or cable and determine whether _______ is a problem.

voltage drop

When we are talking about three phase motors, we are talking about three phases, each ______ degrees out of phase (symmetrical) with the other ________.

120 degrees, phases

The branch circuit supplying the washer-dryer combination must have a rating of at least _____ of the appliance load.. 422.10

125%; load

Even though multipair conductors are no longer used extensively in telephone installations, the size of the conduit should be trade size _____________

3/4 or larger

Schedule _____ PVC is sometimes marked for underground use only.

40

When a load is over ____ amperes, parallel conductors should be considered.

400 amperes.

What is the NEC reference for Conductors Supplying Several Motors or a motor(s) and other load(s)?

430.24

In surface metal raceways, the combined size of the conductors, splices, and taps shall not fill more than ____% of the raceway at the point where ______ and _____ occur.

75%; splices and taps

The minimum size conductor, if all terminals are rated 75 degrees Celsius or higher, is 4AWG, as the allowable ampacity in NEC Table 310.15 (B)(16) is _______amperes.

85

_________ wire is seldom used in branch circuits.

Aluminum

How is voltage drop in a circuit calculated?

By multiplying the current flow(I) times the impedance (Z) Ed = I X Z

How can you demonstrate proof of the flux cancellation principle?

By using a clamp-on ammeter

EMT *can/cannot* be threaded.

Cannot

In the trade, conduit bodies are often referred to as ______ and ______.

Condulets and Unilets