A notification circuit terminal-voltage check
A simplified training-board model supplies 20 volts at the source under the stated alarm condition. The modeled load current is 0.5 ampere and total path resistance is 5 ohms. The fictional appliance data provided with the exercise specifies a minimum terminal voltage of 16 volts under these conditions. A trainee substitutes a nominal 24-volt label for the supplied 20-volt operating value and overstates the available margin. The exercise assumes the stated constant current and lumped resistance for its arithmetic; it does not represent every distributed notification circuit. Students must calculate the terminal value and explain the need for the actual supply and listed-device conditions. No conductor selection, real appliance approval or complete code-compliance determination is provided.
1. Calculate the modeled terminal voltage and margin.
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Voltage drop is 0.5 times 5 = 2.5 volts. The terminal value is 20 minus 2.5 = 17.5 volts, giving a 1.5-volt margin above the supplied 16-volt minimum.
2. What limits the conclusion?
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The result applies to the supplied simplified model. Actual source limits, circuit topology, connected loads, listing, synchronization and applicable requirements need their own assessment.