20. Describe the electrical restoration of drop shutters as manufactured by the Western Electric Company.
21. What complications arise in ringing of party lines and how are they overcome?
22. Give diagram of the complete circuit of a simple magneto switchboard.
23. Sketch night-alarm circuit with relay.
24. What is a convertible cord circuit?
25. State what disadvantages may be encountered under certain conditions with a bridging drop-cord circuit.
26. Are lamps in cord circuits to be advocated on magneto switchboards?
27. What is the function of the cabinet?
28. Give cross-section of upright switchboard as used in the magneto system.
29. What is the purpose of a sectional switchboard?
30. Give a short description of the essential parts of a sectional switchboard.