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The document outlines key concepts related to electricity, including the function of miniature circuit breakers and extra-low voltage circuits. It poses various questions regarding electrical power transmission, national grid voltages in Kenya, and the importance of safety measures like fuses and armoured cables. Additionally, it covers topics such as electrical continuity, testing procedures, and the operation of devices like fire alarms and telephones.

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daniel kipkemboi
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18 views3 pages

Revision

The document outlines key concepts related to electricity, including the function of miniature circuit breakers and extra-low voltage circuits. It poses various questions regarding electrical power transmission, national grid voltages in Kenya, and the importance of safety measures like fuses and armoured cables. Additionally, it covers topics such as electrical continuity, testing procedures, and the operation of devices like fire alarms and telephones.

Uploaded by

daniel kipkemboi
Copyright
© © All Rights Reserved
We take content rights seriously. If you suspect this is your content, claim it here.
Available Formats
Download as DOCX, PDF, TXT or read online on Scribd
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190.

Electricity Level 3

11. Miniature circuit breaker is a mechanical device used to make and break a cinnat h ander normal
and abnormal conditions

12 Extra-low voltage circuits are circuits whose voltage do not exceed 50 V. 4.c. or 30 V Some examples
are bells and telephone circuits.

Questions

Reviscuss the advantages of transmitting large amounts of electrical power over inng distances by
means of high voltages.

2. What are the voltages used in the national grid in Kenya?

3. Give the sequence of supply control equipment at a supply-intake position.

4. Explain why a fuse used in a lighting sub-circuit should not be used in a cooker su circuit.

5. What is the purpose of armouring a cable? State the situations which require the use of an armoured
cable.

6. What is the purpose of using colour coding in cables?

7. What causes low insulation resistance in an installation?


8. Explain the importance of electrical continuity in a metallic conduit installation. When u the conduit
used as E.C.C.?

9. State the difference between a joint box and a junction box.

10. State the reason for having a limited number of cables laid in trunking.

11. Explain the following terms:

(a) Current rating of a fuse.

(b) Current rating of a cable.

(c) Fusing factor.

(d) Fusing current.

12. State the advantages of MCB over a rewirable fuse.

13. Explain how an HRC fuse can cope with transient over loads drawn by an inductive apparatus.

14. What is a final sub-circuit?

15. What is the maximum number of spurs permitted on a ring circuit?

16. State the importance of testing E.C.C.


17. Draw a schematic diagram of a fire alarm installation which has four bells connected in parallel.

18. Discuss, using illustrations, the principle of operation of a simple telephone.

19. What is the recommended sequence of testing a newly completed installation?

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