1. Quiz in progress Don’t forget to put your name on the quiz 1) How hard was the quiz? A.Easy B.Hard C.In-between D.What quiz?

2. Objectives Calculate billing costs (HW problem 2) List electrical devices Select conductor and conduit (HW problem 3) Prepare you for Assignment 1 (due in one week)

3. Electricity Billing (ch. 13) Electrical Use (energy) Peak Demand (power) Power factor Which is largest portion of residential bill? What about for commercial buildings? http://www.austinenergy.com/About%20Us/R ates/Commercial/largePrimaryService.htmhttp://www.austinenergy.com/About%20Us/R ates/Commercial/largePrimaryService.htm

4. Example: September cost of Electricity for ECJ Assume ECJ is 120,000 ft2 and that it needs, on average, 8 W/ft 2 for 8 hours a day, 6 W/ W/ft 2 for 4 hours a day, and 4 W/ft 2 for 12 hours a day Use Austin Energy Large Primary summer service rate 1.5¢/kWh, 12.60 $/peak kW/month Assume no power factor charges

5. 2) What is the correct way to calculate energy consumption? A.kWh ÷ time B.Energy × time C.Power × time D.Power ÷ time

6. 3) What is peak demand? A.0.018 kW/ft 2 × 120,000 ft 2 = 2,160 kW B.0.008 kW/ft 2 × 120,000 ft 2 = 960 kW C.0.018 kW/ft 2 × 120,000 ft 2 × 8 hr = 17,280 kWh D.0.008 kW/ft 2 × 120,000 ft 2 × 30 days = 28,800 kW

7. Solution large primary service $/kW $/kWh Daily $ 12.60 $ 0.015 hourskWkWh 89607680 demand $12,096.00 47202880 energy $ 7,344.00 124805760 TOTAL16320 Total $19,440.00

8. Other Pricing Strategies Time of use pricing Becoming more common for residential and commercial Electricity cost related to actual cost Requires meter HW question #2 Interruptible pricing Utility can shut off electricity for periods of time

9. Protective Devices What are we protecting from? Overcurrent Overvoltage Circuit breakers Switch that responds to thermal or short circuit loads Can be direct digital Fuses Melting metal Can be time-delay

10. Ref: Tao and Janis (2001)

11. 4) Why use fuses instead of circuit breakers? A.Fuses can be used multiple times B.Fuses are more aesthetically pleasing C.Fuses are safer D.Fuses cause less damage to equipment

12. Grounding What is electrical ground? Why do we ground electrical devices/systems? Protect equipment Lightening Protection of people GFCI Sometimes need ungrounded power If the hot side touches ground can trip a circuit Isolate ungrounded systems

13. Ref: Tao and Janis (2001)

14. 5) What is the difference between neutral and ground? A.Neutral is a conductor, ground is an insulator B.Current only flows through neutral when there is a problem C.Current only flows through ground when there is a problem D.Neutral conductor is larger than ground conductor

15. Conductors Material Form Composition Voltage class Insulation Covering Temperature rating

16. Design issues with conductors Material (copper/aluminum) Size of conductor (pg. 145, pg. 189) Conduit requirements (pg. 189) Location Residential (NM,NMC,UF) AC and MC (with conductors) EMT (compression fittings set screws) IMC/Rigid (threaded connections) NEC and local codes

17. Ref: Tao and Janis (2001)

19. Other Issues In general, no more than 40% of raceway can be filled with wiring Romex is allowed Only in residential buildings Only when concealed Why?

20. Conductor Rules Explain each of the following: No more than 4 90 ° bends are allowed between pull boxes In the same conduit: No mixing of high- and low-voltage conductors No mixing control and power conductors No mixing phone and power conductors Do place all three phases in the same conduit

21. Receptacles and switches Receptacles (duplexes) Number Shape Voltage rating Current Rating Number of poles and wires Switches Type (NEC rating) Contact method Speed of operation Voltage rating Number of poles Method of operation Enclosure Duty Other (dimming)

22. Homework Assignment Q1 NEC, Q3 Conductor/Conduit Sizing

23. Problem 2 Demand charges are assessed each month The problem involves calculating the daily cost of electricity Demand charges ÷ 30 Confusion about peak period On-Peak: 1:00 p.m. to 9:00 p.m., Monday through Friday; May 1 through October 31. 8:00 a.m. to 10:00 p.m., Monday through Sunday; November 1 through April 30. Off-Peak: 9:00 p.m. to 1:00 p.m., Monday through Friday; all day Saturday, Sunday, Memorial Day, Independence Day, and Labor Day; May 1 through October 31. 10:00 p.m. to 8:00 a.m. Monday through Sunday; November 1 through April 30.

24. Summary Describe role of electrical system components Calculate billing for an electrical system given the rate structure Size conduit and conductors given current requirements and conductor type Complete HW#1