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Page 153

| Figure 8-23 Metal-clad switch gear: (A) Installing a circuit breaker, and (B) adjusting a control. |

| provided by one or more steel covers or panels that cannot be removed while the circuit is energized, being prevented from doing so by a mechanical interlock. Similarly, an interlock prevents moving the circuit breaker unless it has been tripped. When the breaker is removed from its cubicle, it is automatically isolated from the circuit controlled and thus obtains the same protection afforded by air-break switches (see Chap. 10). |

| Heaters are installed in outdoor breakers, including metal-clad switch-gear, to reduce condensation and prevent freezing of the mechanisms; some are permanently energized and others are thermostatically controlled. |

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