Article 450
Where no secondary overcurrent protection is used, a 480V, 50A transformer shall have an individual overcurrent device on the primary side rated at a maximum _____ of the rated primary current of the transformer.
What is 125 percent? 450.3(B) Table
Dry-type transformers 1,000V nominal or less and not exceeding _____ that are installed in hollow spaces of buildings and not permanently closed in by the structure, shall not be required to be readily accessible.
What is
a. 10 kVA
b. 25 kVA
c. 50 kVA 450.13(B)
d. 75 kVA
Dry-type transformers installed indoors and rated 112 1/2 KVA or less, shall have separation of at least _____ from combustible material unless separated from the combustible material by a fire-resistant, heat insulated barrier.
What is 12 in. 450.21(A)
Overcurrent protection shall be provided in accordance with Table _____.
What is 450.3(A) ?
A fault sensing system that causes the opening of a main switch or common trip overcurrent device for a 3 phase, 4 wire system shall be provided to guard against _____.
What is
a. external faults
b. single-phasing
c. internal faults
d. B & C 450.5(A)
The primary overcurrent protection for a transformer rated 1,000V, nominal, or less, with no secondary protection and having a primary current rating of _____ shall be set at not more than 125 percent or a higher rating that does not exceed the next higher standard rating shall be permitted.
What is
a. 9A or more 450.3(B) Table Note 1
b. less than 9A
c. 2A or more
d. less than 2A
Transformers, other than Class 2 or Class 3 transformers, shall have a disconnecting means located either in sight of the transformer or in a remote location. Where located in a remote location, the disconnecting means shall be lockable open in accordance with 110.25 and _____.
What is
a. its location shall be field marked on the transformer 450.14
b. accessible only to qualified persons
c. placed in supervisory locations
d. none of the above
Transformers insulated with a dielectric fluid identified as nonflammable shall be permitted to be installed _____.
What is both indoors and outdoors? 450.24
The ampacity of the tie shall not be less than _____ %.
What is 67? 450.6(A)(1)
Where secondary ties are used, an overcurrent device rates or set at not more than _____ % of the rated secondary current of the transformers shall be provided in the secondary connections of each transformer supplying the tie system.
What is 250? 450.6(B)
Transformers with ventilating openings shall be installed so that the ventilating openings are _____.
What is not blocked by walls or obstructions? 450.9
A ground responsive protective device on a 3 phase 3 wire ungrounded system shall conform to _____.
What is
a. 450.5(B)(1)
b. 450.5(B)(2)
c. A & B 450.5(B)
d. none of the above
Oil-insulated transformers shall be permitted to be used without a vault in portable and mobile surface mining equipment if _____.
What is:
a. provision is made for draining leaking fluid to the ground
b. safe egress is provide for personnel
c. a minimum 6mm(1/4") steel barrier is provided for personnel protection
d. all of the above 450.26 Ex. 6
Each transformer shall be provided with a nameplate with the following location_____.
What is
a. frequency
b. name of manufacturer
c. primary voltage
d. all of the above 450.11
Individual dry-type transformers of more than _____ rating shall be installed in a transformer room of fire resistant construction having a minimum fire rating of 1 hour.
What is 112 1/2 kVA? 450.21(B)
Transformer top surfaces that are horizontal and readily accessible shall be marked _____.
What is to prohibit storage? 450.9
All energized parts shall be guarded in accordance with _____.
What is:
a. 110.27
b. 110.34
c. A & B 450.8
d. 90
Each doorway leading into a vault from the building interior shall be provided with a tight-fitting door that has a minimum fire rating of _____.
What is
a. 1 hr.
b. 2 hr.
c. 3 hr. 450.43(A)
d. 5 hr.
Less-flammable liquid-filled, transformers shall be permitted to be installed _______.
What is outdoors? 450.23(B)
Where the total capacity does not exceed 112 1/2 kVA, the fault specifies in Part III of Article 450 shall be permitted to be constructed of _____ that is not less than 100mm (4 in.) thick.
What is
a. asphalt
b. steel
c. reinforced concrete 450.26
d. iron
The equipment grounding conductor terminal bar of a dry-type transformer shall be bonded to the enclosure in accordance with 250.12 and shall not be installed on or over any _____.
What is vented portion of the enclosure? 450.10(A)
Liquid insulated transformer installation shall be permitted in accordance with _____.
What is:
a. type 1 or 2 buildings 450.23(A)
b. 250
c. 502
d. 702
Where practicable, vaults containing more than 100 kVA transformer capacity shall be provided with a drain or other means that will carry off any accumulation of _____, unless local conditions make this impractical.
What is:
a. oil or water 450.46
b. oil
c. water
d. anhydrous fluid
A vault shall not be required if nominal voltage does not exceed _____ volts.
What is
a. 500
b. 700
c. 1000 450.26 Ex. 4
d. 2000
With oil insulated transformers on roofs, attaches, adjacent or installed, what shall be safeguarded?
What is combustible material, buildings, windows, fire escapes? 450.27