Unit 10: Commercial Load Calculations Flashcards
Apply commercial load calculations, assess service demand factors, and verify NEC compliance for commercial spaces. (25 cards)
Fill in the blank:
At carnivals and fairs, service equipment shall not be installed in a location that is accessible to unqualified persons, unless the equipment is _________.
lockable
Fill in the blank:
Where the NEC® specifies that one equipment shall be “within sight from” or “within sight of” another equipment, the specified equipment is to be visible and not more than _________ from the other
50 feet
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As a general rule, where a cable is installed parallel to framing members, the cable shall be installed so that the nearest edge of the cable is not less than _________ from the nearest edge of the framing member.
1¼ in.
Generally, how many grounded conductors are permitted to be terminated under an individual terminal within a switchboard or panelboard where the equipment operates at less than 1,000 volts?
one
Fill in the blank:
According to the Code, where Type NM cable is run across the top of framing members or across the face of raters or studding in accessible attics, the cable shall be protected by guard strips that are as high as the cable where the cable is installed within _________ or less of the nearest edge of the scuttle hole or attic entrance.
6 feet
What is the maximum number of size 1/0 AWG THH/THWN copper current-carrying conductors allowed by the NEC® at any cross-sectional area of a 4 in. x 4 in. metallic wireway?
17
Where electrical boxes are installed in a wall having a combustible finish and located above a kitchen wall countertop they shall be installed _________.
flush or projected from the finish surface
Fill in the blank:
A single-phase, 125-volt, 15- or 20-ampere receptacle outlet shall be installed at each residential kitchen, breakfast room, or dining room wall countertop and work surface that is at least _________ or wider.
12 in.
Fill in the blank:
Given: A one-family dwelling unit is to have the following fastened in place appliances installed:
- 1,200 VA dishwasher
- 4,000 VA water heater
- 1,150 VA garbage disposer
- 700 VA attic fan
- 1,920 VA garage door opener
The demand load, in VA, on the ungrounded (line) service entrance conductors for the listed appliances is _________ when applying the general method of calculations for dwelling units.
6,728 VA
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Nonmetallic cable trays shall be made of _________ material.
flame-retardant
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Switches are to be located a horizontal distance of at least _________ from
the inside walls of an indoor placed spa or hot tub.
5 feet
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Direct buried cables installed under an open field of vacant property must have a minimum cover depth of _________ when the applied voltage is not more than 1000 volts ac.
24 in.
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Shore power for boats docked in marinas and boatyards shall be provided by single receptacles that are of the locking- and grounding-type, mounted at least 12 inches above the deck surface, and rated not less than _________.
30 amperes
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For electrical systems over 1000 volts, where pulls of conductors in junction boxes are being made, the length of the box shall not be less than _________ the outside diameter of the largest shielded or lead-covered conductor or cable entering the box.
48 times
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Each grounding electrode plate of bare or electrically conductive coated
iron or steel material shall expose not less than _________ sq. ft. of surface to
exterior soil.
2
Fill in the blank:
Installation of direct buried cables in an area that is subject to movement
by frost or settlement of the soil shall be _________.
placed with “S” loops or provide an adequate allowance for movement
Fill in the blank:
Busways shall be securely supported at intervals not exceeding _________ unless the raceway is otherwise designed and marked.
5 feet
Fill in the blank:
At least _________ of free conductor, measured from the point in the box where it emerges from its raceway, shall be left at each junction box or device box for splices or connections to devices.
6 in.
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As a general rule, each motor fuel dispenser shall be provided with a identified emergency shutoff or electrical disconnect not less than _________ from the fuel dispensing devices.
20 feet
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Electrical installations of over 1000 volts which are controlled by lock(s) or other approved means, shall be considered to be accessible to _________.
qualified persons only
What determines the required size of an equipment grounding conductor of the wire type?
- rating of the branch-circuit
- short-circuit
- ground-fault protective device
The NEC® mandates expansion fittings for rigid PVC conduit shall be provided to compensate for thermal expansion. In an environment where the normal annual change in temperature is 100°F, and the length of the PVC is 100 feet, how much allowance for thermal expansion must be considered?
4.06 in.
Fill in the blank:
Where size 250 kcmil copper conductors are installed in vertical raceways of a multi story occupancy or structure, each conductor shall be supported at the top of the vertical raceway or as close to the top of the vertical raceway as practical, and at intermediate supports at intervals not greater than _________.
60 feet
Fill in the blank:
The minimum clearance between luminaires installed in clothes closets and the nearest point of a closet storage space shall be _________ where surface-mounted incandescent or LED luminaires are installed.
12 in.
