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PRACTICAL ELCTRICITY

PRACTICAL ELCTRICITY. National Electric Code. Not For Publication. The Code. What it is Purpose Terms & Definitions Qualified Wire & Conduit Selection Physical Application Grounding, GFCI AFCI Disconnects Load Panels. The Code. Three year cycle 2002, 2005, 2008 Interpretations

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PRACTICAL ELCTRICITY

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  1. PRACTICAL ELCTRICITY National Electric Code Not For Publication

  2. The Code • What it is • Purpose • Terms & Definitions • Qualified • Wire & Conduit Selection • Physical Application • Grounding, GFCI AFCI • Disconnects Load Panels

  3. The Code • Three year cycle • 2002, 2005, 2008 • Interpretations • Usually Adopted by city as is • Purpose = Practical safeguarding of persons and property from hazards arising from the use of electricity • If comply = free from Haz, but not necessarily efficient, convenient, or adequate for good service or future expansion of elec use.

  4. Grounding 250 • Metal Water Pipe 250.52A1 • Bond around Water Meters • Water Pipe Cannot Be only Electrode 250.53D2 • Cu Rods Min size 1/2” x 8’ L&L. Vertical, below grade • 2 rods • Metal Well Casings • Metal building frame, exterior siding • Do not Use Gas Pipe as electrode

  5. Grounding Electrode • Must connect to Neutral at or before service • Sized per service size, 100, 200, etc • No splices • Connection to water pipe must be made within 5 ft of entrance to bldg • Buried Clamps L&L • One conductor per clamp • Connections accessible except buried

  6. Bonding • Bonding ensures electrical continuity to prevent differences of potential between conductive components. • Use parts made for the task • Lightening Rods are to be bonded to electrical system • Bond all piping hot cold and gas

  7. Equipment Grounding Conductor • Sized per OCPD • 15A = 14 awg • 20A = 12 awg • Can be bare, green, green with yellow stripe • Can be > #6 OK to strip bare or use green tape • Can be the rigid pipe, or emt or imt

  8. Ground Fault Circuit Interrupters • Detect the escape of electrical current outside the intended path. • Breakers • Outlets • Blind

  9. GFCI, Where? • All Kitchen counters • All bathrooms • Within 6 ft of sink • HVAC Recept • Garages • Unfinished basements • Within 20 ft of a pool • Pool pumps, spa, hot tubs • Front and rear of dwelling

  10. Arc Fault Circuit Interrupters • Arc Fault breakers are intended to provide protection by opening the circuit if an arcing fault is detected. Often have GFI protection built in

  11. Service Drops & Entrance Cables • Height 12 ft driveway • 22.5 ft above a pool • No trees for support • Use wire rated for such use • Use warning ribbon 12 above underground feed lateral • 3 feet around window openings SE Conductors • Identify the Neutral with white tape • Protect them against damage • Utilize a drip loop • Clamp and strap as required

  12. Service InstallationDo/Don’ts • Meters too close to gas pipe 3 Ft from feed side, 10” from house side • Wrong height • Not accessible • Length of wires at weather head too short • Roof heights not correct • Weather head should be 1 foot higher than point of attachment • Point of attachment too far from weather head • Service cable has to be on the exterior • Working space at panels insufficient

  13. Panels and Sub Panels

  14. Service Panel • Neutral Conductor is bonded to service enclosure. • Once Neutral leave service they must always be isolated from equipment and enclosures • Front working clearance 30 w and 36 deep • Wet, must be rated for area? • All open KO filled • NO panels in bathroom or closet • Must be accessible • All breakers correct brand • One wire per screw, ONLY • Clearly marked circuit ID • Approved handle ties breakers • Multi-wire feeds must have handles tied • Use antioxidant on Al wire

  15. Service & Feeder Calculations • Guidelines in the code help anticipate the size and number of circuits needed to supply the loads in a home. Code states service conductors, feeders, branch circuits must be sufficient to serve the connected loads. • Since not everything will be ON at the same time, code allows to use demand factors.

  16. Multi-wire Circuits • Unbalanced Unequal loads requires the neutral to carry the current

  17. Branch Circuits • They are intended to supply the loads. • Required branch circuits are minimal, more are required for convenience and safety. • Smallest branch circuit is #14 with 15A breaker • Rule of thumb, 1 GP cir per 500 sq feet • Wall > 2 ft req recept • Hallways greater than 10 req recept

  18. Kitchen • Min 2 20A mp GFI Circuits • Serve no other areas or items • DW and Disposer separate cir • Island / Peninsulas require outlets • If > 6 overhang outlet can be 12” below

  19. Bathrooms • Within 3 ft of basin • Dedicated 20 A • Pumps equipment accessible tubs

  20. Laundry • 1, 20A w/ in 6ft of appliance GFCI • Dryer circuit 30 Amp/250V

  21. Other • Outdoors, front and back accessible <6.5 ft • Luminaries required at grade level doors. • ADA ?

  22. Ampacity of Wire

  23. Cable Systems • NM, NMB • BX • UF • SE SEU

  24. NM • OK in dry locations • Protect from damage • Strain reliefs • Use 60 deg column (90 deg wire) • Derate when bundled in a hole • Secure w/in 12” box & 4.5’ intervals • Don’t kill the staples

  25. BX • Dry Locations only • Secure w/in 12 of box & 4.5’ • Use insulated bushings, red hats • Don’t bring bonding wire into box • Secure each joist if underside

  26. UF • Inside use same rules as NM • Bury per table • Protect where emerging from earth 18” • Uv resistant where necessary

  27. SE • Intended for service entrance • Inside same rules as NM • SEU same rules as UF • Gradual bends (5x dia) • Weatherproof connections

  28. Voltage Drop • Consider long runs, target between 3-5% • Use larger wire

  29. Protecting Cables • Nailer Plates L&L • Rafters, running boards • Standoff Clamps

  30. RacewaysConduits, Tubing, Conduit Fill • EMT • RMC • LFMC • ENT Smurf • RNC PVC

  31. Installation Requirements • 360 • Clean and Ream • Condulets Boxes remain accessible • 40% Fill if >2 conductors

  32. EMT • Do Not Bury • Use Raintight where required • Secure at 10’ intervals • Supports condulets not boxes

  33. Rigid Conduit • OK to bury • Clean and Ream • Support at 10’ intervals

  34. Liquid Tight Flex Conduit • OK for WET • 6 Ft Rule

  35. ENT Do not bury Temp max 122F Secure 3 Ft PVC OK Bury, depth? Temp max 122F Support often Expansion joints Electrical Nonmetallic TubingRigid Non Metallic Conduit PVC

  36. Conduit Fill

  37. Condulets • Various configurations and sizes • No splices !!

  38. Boxes • Boxes are necessary to safely enclose and protect wiring splices and support devices and light fixtures

  39. Boxes, Generalities • Metal must be grounded • Must be accessible • 1/4 “ setback max • No gaps by wall board • Must be supported/mounted • Outside require In use Covers

  40. Box Fill • Size of box MUST be OK to provide enough free space for conductors

  41. Calculating Box Fill • Count number and size • Internal clamps count as 1 • Devices count as 2 • EGC counts as 1 • Pigtails Do No Count

  42. Box Calculation Example

  43. Other Box Requirements • In Use Covers • Cutouts and depth

  44. Appliances • Anything other than lighting • Cord and plug OK for disconnect • Disconnect means are usually in sight

  45. Kitchen • Disposer • DW

  46. HVAC • Disconnect in Sight of Outside Unit • Requires 20A GFI Rec

  47. Furnace • Disconnect In Sight • Some manuf require fuses

  48. Water Heater • Disconnect in sight • Bond pipes, all 3

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