4. When is a piece of apparatus called "self-protecting"?
5. Why must a protector for telephone apparatus work more quickly for a large current than for a small one?
6. State the general problem which heating hazards present with relation to telephone apparatus.
7. What is the most nearly universal electrical hazard?
8. Sketch and describe the saw-tooth lightning arrester.
9. Make diagram of the carbon-block arrester and state its advantages.
10. Describe a vacuum arrester.
11. Explain the reason for placing an impedance in connection with the lightning arrester.
12. What is the purpose of the globule of low-melting alloy in the Western Electric Company's arrester?
13. Why are not fuses good lightning arresters?