Load calculations for heating and air conditioning systems are crucial in electrical design and installation. These calculations ensure that electrical systems can safely and efficiently handle the power demands of HVAC equipment. Understanding how to perform these calculations is essential for passing the NEC electrical exam and for real-world applications in electrical work.
A residence has a 3-ton central air conditioner with a nameplate rating of 3,500 VA, and an electric furnace rated at 15 kW. The air handler for the AC system draws 800 VA. Calculate the total VA that should be included in the service calculations.
Calculate the load for a building with a 5-ton heat pump (nameplate: 6,000 VA) and supplementary strip heating rated at 10 kW. The heat pump has a 1,500 VA air handler. What is the total wattage to be considered for service calculations?
A small office has three 2-ton ductless mini-split systems, each with a nameplate rating of 2,400 VA. There is also a 7.5 kW electric baseboard heating system. What is the total VA to be considered for service calculations?
Key phrases to look out for in Heating & AC load calculation questions:
When you spot these elements:
To correctly apply NEC Articles 220.60, 220.50, and 220.51, focus on these main elements:
Summary of how to use the codebook:
A residence has a 3-ton central air conditioner with a nameplate rating of 3,500 VA, and an electric furnace rated at 15 kW. The air handler for the AC system draws 800 VA. Calculate the total VA that should be included in the service calculations.
Step 1: Identify and convert all loads to VA
Step 2: Calculate total cooling load
Step 3: Identify heating load
Step 4: Apply NEC 220.60 for non-coincident loads
Step 5: Compare the loads
Step 6: Determine the final load
Final Answer: 15,000 VA should be included in the service calculations for heating and cooling.
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