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Electrical Installation and Derating Factors

Electrical Installation and Derating Factors

Assessment

Interactive Video

Mathematics, Science, Professional Development

10th - 12th Grade

Practice Problem

Hard

Created by

Olivia Brooks

FREE Resource

The video tutorial explains the use of the On-Site Guide, focusing on Appendix F, which covers current carrying capacities and voltage drop in copper conductors. It breaks down a complex formula into understandable parts, considering installation and environmental conditions. The tutorial provides practical examples, highlights common errors, and offers a recap of the process. It concludes with resources for further learning.

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10 questions

Show all answers

1.

MULTIPLE CHOICE QUESTION

30 sec • 1 pt

What is the primary purpose of the on-site guide?

To advertise electrical services

To offer detailed information on electrical installations

To provide a list of electrical tools

To sell electrical products

2.

MULTIPLE CHOICE QUESTION

30 sec • 1 pt

What does the symbol 'I T' represent in the formula?

Installation temperature

Insulation type

Tabulated current carrying capacity

Total current

3.

MULTIPLE CHOICE QUESTION

30 sec • 1 pt

What does 'I N' stand for in the context of the formula?

Insulation number

Nominal value of the fuse or circuit breaker

Installation number

Nominal voltage

4.

MULTIPLE CHOICE QUESTION

30 sec • 1 pt

Which factor is used to account for the effect of thermal insulation on a cable?

C I

C F

C A

C T

5.

MULTIPLE CHOICE QUESTION

30 sec • 1 pt

In the first worked example, what is the derating factor for a 50mm length of thermal insulation?

0.88

0.75

0.95

0.65

6.

MULTIPLE CHOICE QUESTION

30 sec • 1 pt

For a 32 amp circuit breaker passing through 50mm of thermal insulation, what is the required tabulated current carrying capacity?

28 amps

40 amps

36.36 amps

32 amps

7.

MULTIPLE CHOICE QUESTION

30 sec • 1 pt

In the second worked example, what is the derating factor for a BS-3036 semi-enclosed fuse?

0.65

0.88

0.725

0.95

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