Final answer:
The closest correct current that a 1Ø boiler with two heating elements rated at 12.3 kW at 240 volts would draw from a 480-volt circuit is 25.625 A per element. Given the options provided, none of them accurately represent the calculated current; however, the value 51.25 A represents the combined current for both elements, which is not what the question asks.
Step-by-step explanation:
The nameplate on a 1Ø boiler that operates at either 240 or 480 volts indicates that each of its two heating elements has a rating of 12.3 kW at 240 volts. To determine the current the boiler will pull through each branch circuit conductor when connected to a 480-volt circuit, we apply the power formula, P = IV, where P is power in watts, I is current in amperes, and V is voltage.
When the boiler is connected to 480 volts, the power rating for each element does not change, but because P = IV, I = P/V. So for each element, I = 12,300 W / 480 V which equals approximately 25.625 A. Since there are two elements, the total current is twice that, so it's 51.25 A. However, the question asks for the current through each branch circuit, which is 25.625 A. None of the options accurately reflect the correct calculation based on the given information. The closest correct answer should be 25.625 A, not 51.25 A, since that is the addition of two elements' currents, or it might be a mistake in stating the voltage or power ratings in the options provided.