What should a limit control for a group A boiler be wired to interrupt when the contacts open?

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A limit control for a group A boiler is designed to ensure safe operation by interrupting the electrical circuit when certain conditions are met, such as overheating. When the contacts of the limit control open, they should disconnect the power supply to the burner or heating element. This means that it needs to be wired to the underground side of the circuit, which provides the most effective means of cutting off power and ensuring that no current continues to flow to the components that could otherwise pose a safety hazard.

Wiring to the underground side means that when the limit control contacts open, the flow of electricity is halted at the source, effectively shutting down the equipment. This approach safeguards the boiler from operating under unsafe conditions, which is critical for preventing damage and ensuring safety.

In contrast, wiring options like the upper side of the circuit or the electrical panel would not effectively ensure that the circuit is fully interrupted. Wiring to the ground connection is not appropriate for this use, as it would not cut off power and could lead to unsafe operating conditions. Thus, the proper identification of where the limit control should be wired is essential for maintaining system integrity and safety.

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