Answer: the demand load of the electric clothes dryers on the ungrounded service-entrance conductors in this 10-unit multifamily apartment building is 30,000 VA.
Step-by-step explanation:
To determine the demand load of the dryers in VA (volt-amperes) on the ungrounded service-entrance conductors, we'll use the general method of calculations for multifamily dwellings.
The general method typically involves using demand factors from the National Electrical Code (NEC). According to NEC, the demand factor for electric clothes dryers in multifamily dwellings is calculated based on the number of units and the rated load of the dryers.
Given:
Number of units: 10
Rated load of each dryer: 4 kW
First, let's calculate the total load for all dryers:
Total load = Number of units × Rated load per unit
Total load = 10 units × 4 kW/unit
Total load = 40 kW
Now, we'll apply the demand factor. For multifamily dwellings, NEC provides a demand factor of 75% for electric clothes dryers.
Demand load = Total load × Demand factor
Demand load = 40 kW × 0.75
Demand load = 30 kW
Finally, we'll convert the demand load from kilowatts (kW) to volt-amperes (VA) since both are units of power:
1 kW = 1000 VA
So,
Demand load (in VA) = Demand load (in kW) × 1000
Demand load (in VA) = 30 kW × 1000
Demand load (in VA) = 30,000 VA
Therefore, the demand load of the electric clothes dryers on the ungrounded service-entrance conductors in this 10-unit multifamily apartment building is 30,000 VA.
