Calculate the minimum size of copper serviceentrance conduct

Calculate the minimum size of copper service-entrance conductors and grounding electrode conductor required for a residence containing the following: 24 ft.x 38 ft. The dwelling will have:

a 12-kW, 120/240-volt electric range.

a 5-kW, 120/240-volt electric clothes dryer consisting of a 4-kW, 240-volt heating element, a 12-volt motor, and 120-volt lamp that have a combined load of 1 kW.

a 2200-watt, 120-volt sauna heater

six individually controlled 2-kW, 240-volt baseboard electric heaters.

a 12-ampere, 240-volt air conditioner.

a 3-kW, 240-volt electric water heater.

a 1000-watt, 120-volt dishwasher.

a 7.2-ampere, 120-volt food waste disposer.

a 5.8-ampere, 120-volt attic exhaust fan.

Determine the sizes of the ungrounded \"hot\" conductors and the neutral conductor. Use Type THWN. Use 310.15(B)(7). Also determine the correct size grounding electrode conductor.

Do not forget to include the required two 20-ampere small-appliance circuits and the laundry circuit.

The panelboard is marked for 75 degree C terminations.

You may use the blank Single-Family Dwelling Service-Entrance Calculation form in your textbook Appendix, or use the form as a guide to make your calculations in the proper steps.

Question 1

Two _______ AWG THWN ungrounded \"hot\" conductors

Question 2

One _______ AWG THWN or bare neutral conductor

Question 3

One _______ AWG grounding electrode conductor.

Solution

ans1. P = i² *R = i^{2 *} resistivity *length / Area

area = 24 *38 = 912

resistivity of copper = 1.7 * 10^-8

^{P =} 40000 W

i = 20A

L = 1.25 nm

for 2 AWG

L = 1.25 * 2 = 2.5nm

Question 2 :

for 1AWG

P = 1 KW

L = 0.75 nm