# Electricity

Formula Tables

Formula Wheel, Ohms Law Circle, & PIE Circle

Series & Parallel Circuits

Voltage Drop Calculations

MikeHolt_Section01_Electricial Basics

• Unit 01: Basic Electrical Math and Formulas
• Unit 02: Electrical Circuits
• Unit 03: Alternating Current

MikeHolt_Section02_Conductor Sizing and Protection

• Unit 06: Conductor Sizing and Protection Calculations

MikeHolt_Section03_Raceway, Conductors, and Box sizing

• Unit 05: Raceway, Conductors, and Box Calculations

MikeHolt_Section04_Motors, Transformers, and HVAC

• Unit 04: Motors & Transformers
• Unit 07: Motor and Air Conditioning Calculations

MikeHolt_Section05_Voltage Drop Calculations

• Unit 08: Voltage Drop Calculations

MikeHolt_Section06_Dwelling Units

• Unit 09: Dwelling (Single) Unit Calculations
• Unit 10: Multi-Family Dwelling Calculations

MikeHolt_Section07_Commercial Calcs

• Unit 11: Commercial Calculations

MikeHolt_Section08_Transformers

• Unit 12: Transformer Calculations

Definations

Laws

Minnesota Statutes

Character Map & Alt-Codes

# NEC Code Book Notes

#### Important Code Book Sections

Codebook Section Page Description Notes
240.6(A) 70-95 Fuse Sizes
210.52 70-64 Receptacles Dwelling Units
310.15(B)(16) 70-150 Table_Conductor Amps
210.19(A)-Note 4 Voltage Drop
215.2(A)-Note 2 Voltage Drop
210.8 Ground Fault
210.13 Ground Fault
215.10 Ground Fault
240.13 Ground Fault

#### Formulas Included

70-147 (& 154) Ambient Temperature Correction
70-149 Conductor Ampacities
70-689 Temperature Change Equation
70-690 Effective Impedance
70-795 I=VA / (E * 1.732)
70-801 Conductor Ampacity
70-806 Availability of System Performance
70-102 Short circuit formulas for conductors
?? Formulas

Ch.9-Tables contain:

• Raceway Sizing & Bend Radius
• Conductor Fill & Voltage Drop

# Metric Notes

• KW = 1000 watts
• KVA = 1000 volt-amps
• KCMil = 1000 circulr-mills
• KFt = 1000 feet
• kVA = Watts / 1000
• kWh = Watts * Hours / 1000

# Equivalences and Acronyms

• E = V
• R = (Ohm’s symbol)
• P = W = VA
• I = A
• CEMF = Counter-Electromotive Force = back-EMF = induced voltage = self-inductance
• Apparent Power = Volt-Amps = VA = Voltage = E

# Key People of Electrical History

Heinrich Hertz

Andre-Marie Ampere

Nikola Tesla

Thomas Edison

George? Westinghouse

# Class Notes

Bring Gum, water, snacks to test

Annex D has examples and math calcs – study

• Multi-Dwelling Units

╧ to earth:

• limits spikes
• limits static electricity
• limits over-current
1. Grounded = Neutral
2. Grounding = tied to earth
3. Ungrounded = hot wire

Voltage Drop

• k = kilo / 1000 / will be given in problem
• i = current / amps
• l = length
• cm = circular mils, Ch.09-Table 08

1 Ø

• VD = 2kil/ cm
• CM = 2kil / vd

1 Ø or 3 Ø

• VD = √3 kil / cm
• cm = √3 kil / vd

OH/NH = OG/NG

• Old hot / new hot = old ╧ / new ╧

Table 250.66

• grounding wire
• earth to panel
• applies to waterline and building frame

Table 250.102C

• hot wires

Disregard Ch.’s 1 thru 7 unless referrenced to in Ch. 08NEC Ch. 08

725.3

• Only those sections of article 300

Continuous duty

• Considered 3 hours or more

Fuses

• 80% load if continuous
• 100% load if non-continuous

Impedence

• Total opposition to current flow
• DC circuits
• resistance
• AC circuits
• resistance + impedence
• Both measured in Ω

Table 110.28

• Pg 70-50
• Watertight

Pipe Fill

• fill nipple to 60% (up to 24″ length)
• fill conduit to 40% at most

Insulation

• Pipe fill – Include in calculations
• Box fill – Do not include in calculations

Use table 4 & 5 to see how much to fill a pipe

Table C1

• how many of the same cable can get into 1 pipe

Table 5A

• same size wire but compact

Table 8

• Circular mils given

Receptacles-Walls

• 210.52(A)(2)
• 2′
• 6′
• 12′

Receptacles-Kitchen Counters

• 1′
• 2′
• 4′

Interrupting Rating

• 110.9
• LEARN THIS!! – unsure the formula – Notes pg 8

250.50

• Grounding = bare green electrode buried in earth

Use 80% and 125% if need to guess

• Cu” = box fill
• Sq” = Pipe fill
• Pg  10-11, 15, 50, 51, 53-to-61
• Pg 65-71
• Pg 97-117

PF = w / va

Eff = Out-Eff / In-Eff

SF (service factor) = ??

Transformer Formula

• VAP = VAS
• NP / NS = VP / VS = IS / IP

FD – 2 kil / cmil

CM = 2kil / vd

# Questions

• Power loss in relation to P=IE
• VAC with Unity Power Factor
• Difference between a volt-amp and a watt?
• I = P(E*1.732)
• Where is Tables 430.3(B)?? Replaced by 450.3(A)  (B), pg 70-333?

# To Do

• Fix Voltage Drop Formulas in table
• Center Formula Wheel Memorization Tool Table
• NOTE: Write out Q47, pg 37, MH book
• add cell borders to series and parallel rule charts
• Capacitive Reactance is a

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