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Electrical Systems Midterm Review: Residential & Commercial

Prepare for your electrical systems midterm by reviewing key concepts including NEC, power calculations, panel sizing, lamp technologies, CU calculations, and more.

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Electrical Systems Midterm Review: Residential & Commercial

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Presentation Transcript

  1. 1) What area are you most nervous about for the midterm? • Residential electrical systems • Commercial electrical systems • Panel and branch circuit sizing • Lamp technology and light level requirements • CU calculations and fixture calculations

  2. Objectives • Review material for midterm • Electrical systems • Lighting systems • Review session • ECJ 6.406 (this room) on Monday 10/4 at 5pm

  3. Electrical Systems • What is NEC? What does it tell you? • What is single phase power? What is three phase power? • How do you calculate power usage? • How do you size conductors? • What is conduit and how do you size it? • How do you calculate electrical bills for a commercial building? For a residential building?

  4. Residential Electrical (1Ø) • How many phases are there? How many voltage levels? What voltages are typical? • How does air conditioning influence the required electrical load? How is central heating accounted for differently from non-central heating? • How do you size the panel

  5. Commercial Electrical (3Ø) • What is a branch circuit? • What is the difference between MLO and MCB? • What is the difference between single pole and multiple pole loads? • What is the difference between 2 and 3 pole loads? • How do divide the wattage among legs for multi-pole loads?

  6. Commercial Panels • How do you find the total load on each neutral leg? On each hot leg? • How should you size the hot feeders? • How should you size the neutral feeder? • How should you size the panel? • How should you size the conductors coming into the panel? • Do you need to size conduit for the panel feeders?

  7. Branch Circuits • What is a branch circuit? • What is an example of a branch circuit rule? • How do you size the circuit breaker for a branch circuit? Is the procedure different for a multi-pole breaker? • How do you size the conductor for a branch circuit? • When do you use the 1.25 safety factor? • When do you use √3?

  8. Commercial Electrical • When do you need a transformer? How do you size it? • How do calculate the current coming into a transformer? • Why do we segregate loads on panels? • When do you need to size a switch? How do you size it? • How do you size a wireway? • What do you do if no conductor is big enough?

  9. Electrical Systems • What is the most confusing thing about electrical systems? • What is the least confusing thing about electrical systems?

  10. Lighting Design • What is the difference between illuminance and luminance? • What is a lumen? Does it relate to illuminance or luminance? • In addition to quantity of light what are five other variables which influence lighting design?

  11. Lighting Quantities and Quality • What is CRI? • What is lamp lifetime? • What is efficacy? How does it differ from efficiency?

  12. Lamp Technologies • What are three different kinds of lamps? • How do halogen lamps differ from incandescent lamps? • How do fluorescent laps work? • How do HID lamps work? • What is a ballast? When do you need a ballast? • What lamp has the highest/longest CRI/lifetime/efficiency?

  13. Determining Required Lighting Levels • Where do you start? • What other pieces of information do you need to know? • What is a weighting factor? • How many parameters contribute to the weighting factor? • What is the difference between a lux and a footcandle?

  14. CU calculations • What is CU and what does it mean? • Where do you start when calculating CU? • How does room geometry influence the CU? • What is PAR? What is a CR? • What is the difference between a base reflectance and a cavity (or effective) reflectance? What symbols do you use for each? • How do you calculate effective reflectances?

  15. CU Calculations • Once you have the CR and effective reflectances how do you find the CU? • When do you have to calculate the floor cavity reflectance? What do you do if it is not 0.20? • Once you have the CU, how do you calculate the number of fixtures? • What is S/MH and how does in influence the fixture calculation?

  16. Your Turn - Questions?

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