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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 Not For Publication.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


National Electric Code

Not For Publication

the code
The Code
  • What it is
  • Purpose
  • Terms & Definitions
  • Qualified
  • Wire & Conduit Selection
  • Physical Application
  • Grounding, GFCI AFCI
  • Disconnects Load Panels
the code1
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.
grounding 250
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
grounding electrode
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
  • 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
equipment grounding conductor
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
ground fault circuit interrupters
Ground Fault Circuit Interrupters
  • Detect the escape of electrical current outside the intended path.
  • Breakers
  • Outlets
  • Blind
gfci where
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
arc fault circuit interrupters
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
service drops entrance cables
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
service installation do don ts
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
service panel
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
service feeder calculations
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.
multi wire circuits
Multi-wire Circuits
  • Unbalanced Unequal loads requires the neutral to carry the current
branch circuits
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
  • 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
  • Within 3 ft of basin
  • Dedicated 20 A
  • Pumps equipment accessible tubs
  • 1, 20A w/ in 6ft of appliance GFCI
  • Dryer circuit 30 Amp/250V
  • Outdoors, front and back accessible <6.5 ft
  • Luminaries required at grade level doors.
  • ADA ?
cable systems
Cable Systems
  • NM, NMB
  • BX
  • UF
  • SE SEU
  • 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
  • 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
  • Inside use same rules as NM
  • Bury per table
  • Protect where emerging from earth 18”
  • Uv resistant where necessary
  • Intended for service entrance
  • Inside same rules as NM
  • SEU same rules as UF
  • Gradual bends (5x dia)
  • Weatherproof connections
voltage drop
Voltage Drop
  • Consider long runs, target between 3-5%
  • Use larger wire
protecting cables
Protecting Cables
  • Nailer Plates L&L
  • Rafters, running boards
  • Standoff Clamps
raceways conduits tubing conduit fill
RacewaysConduits, Tubing, Conduit Fill
  • EMT
  • RMC
  • LFMC
  • ENT Smurf
installation requirements
Installation Requirements
  • 360
  • Clean and Ream
  • Condulets Boxes remain accessible
  • 40% Fill if >2 conductors
  • Do Not Bury
  • Use Raintight where required
  • Secure at 10’ intervals
  • Supports condulets not boxes
rigid conduit
Rigid Conduit
  • OK to bury
  • Clean and Ream
  • Support at 10’ intervals
liquid tight flex conduit
Liquid Tight Flex Conduit
  • OK for WET
  • 6 Ft Rule
electrical nonmetallic tubing rigid non metallic conduit pvc

Do not bury

Temp max 122F

Secure 3 Ft


OK Bury, depth?

Temp max 122F

Support often

Expansion joints

Electrical Nonmetallic TubingRigid Non Metallic Conduit PVC
  • Various configurations and sizes
  • No splices !!
  • Boxes are necessary to safely enclose and protect wiring splices and support devices and light fixtures
boxes generalities
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
box fill
Box Fill
  • Size of box MUST be OK to provide enough free space for conductors
calculating box fill
Calculating Box Fill
  • Count number and size
  • Internal clamps count as 1
  • Devices count as 2
  • EGC counts as 1
  • Pigtails Do No Count
other box requirements
Other Box Requirements
  • In Use Covers
  • Cutouts and depth
  • Anything other than lighting
  • Cord and plug OK for disconnect
  • Disconnect means are usually in sight
  • Disposer
  • DW
  • Disconnect in Sight of Outside Unit
  • Requires 20A GFI Rec
  • Disconnect In Sight
  • Some manuf require fuses
water heater
Water Heater
  • Disconnect in sight
  • Bond pipes, all 3
paddle fans
Paddle Fans
  • Use L&L box
  • >70 requires separate support
  • Normal up to 35
  • 7 Ft Height
  • Point to remember is bulbs create heat, and must be kept from combustible materials
  • There are required lighting locations
  • Clearances for recessed
  • Closets are also special
required lighting
Required Lighting
  • Wall switch control in all habitable locations bedrooms, kitchens and bathrooms
  • May be switched outlets except in bathroom and kitchen
  • Garage, halls, and stairs require switched lighting
recessed lighting
Recessed Lighting
  • Non IC away from insulation 3”
  • Non IC away from combustibles ½”
  • IC OK contact insulation and combustibles
  • Don’t over wattage, read trim and rough labels
switching requirements
Switching Requirements
  • All Switches must be grounded
  • Cover must be large enough to cover
  • Re-identify white wire if used as an ungrounded
  • No Overhead Wires or 22.5 clearance
  • No EMT
  • Min EGC #12 and no splices
  • GFCI on Pump
  • GFCI on all lighting
  • GCFI on everything
arrays and components
Arrays and Components
  • Remember any building codes
  • L&L Equipment
  • Correct OCPD
  • DC Ground fault protector
  • All current rated continuous,
  • Must be suitable for intended application
  • All conductors sized 125% of namplate
  • Transfer Switches
    • Sign req at service advising of generator
    • If Neutral is switched, cannot be bonded to generator case
other stuff
Other Stuff
  • Knob and Tube