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Engineering 43 Electrical Safety Bruce Mayer, PE Licensed Electrical & Mechanical Engineer BMayer@Chabot. College. Engineering 43 Electrical Safety Bruce Mayer, PE Licensed Electrical & Mechanical Engineer [email protected] College. edu Engineering-43: Engineering Circuit Analysis 1 Bruce Mayer, PE [email protected] College. edu • ENGR-43_Lec-01 a_Electrical_Safety. ppt

Electrical Circuits § Electrical Power source § Electrical Components Interconnected with Wires § Electrical Electrical Circuits § Electrical Power source § Electrical Components Interconnected with Wires § Electrical user Engineering-43: Engineering Circuit Analysis 2 Bruce Mayer, PE [email protected] College. edu • ENGR-43_Lec-01 a_Electrical_Safety. ppt

Rules of Electricity § Electricity Travels In A Completed Circuit § Electricity Always Travels Rules of Electricity § Electricity Travels In A Completed Circuit § Electricity Always Travels In The Path Of Least Resistance § Electricity Tries To Travel To Earth Ground Engineering-43: Engineering Circuit Analysis 3 Bruce Mayer, PE [email protected] College. edu • ENGR-43_Lec-01 a_Electrical_Safety. ppt

Electricity and People § A Person Usually Offers Low Resistance For The Electricity § Electricity and People § A Person Usually Offers Low Resistance For The Electricity § The Person Forms A Completed Circuit When Touching The Ground § Electricity Always Tries To Travel To Ground Engineering-43: Engineering Circuit Analysis 4 Bruce Mayer, PE [email protected] College. edu • ENGR-43_Lec-01 a_Electrical_Safety. ppt

Conditions for Electrical Shock § Source of Electrical Potential (Voltage) • Relative to EARTH Conditions for Electrical Shock § Source of Electrical Potential (Voltage) • Relative to EARTH GND – Most Electricity Will Flow Into the DIRT § An Electrical Conductor (a Person) § Completed Connection Engineering-43: Engineering Circuit Analysis 5 Bruce Mayer, PE [email protected] College. edu • ENGR-43_Lec-01 a_Electrical_Safety. ppt

Volts and Amperes § Voltage = Amps X Ohms (Ω = Resistance) § Ω’s Volts and Amperes § Voltage = Amps X Ohms (Ω = Resistance) § Ω’s Converts Volts To Amps § Typical Industrial Voltages • 115 Volts AC » 60 milli. Amps (m. A) Shock • 230 Volts AC » 120 m. A Shock • 460 Volts AC » 240 m. A Shock Engineering-43: Engineering Circuit Analysis 6 Bruce Mayer, PE [email protected] College. edu • ENGR-43_Lec-01 a_Electrical_Safety. ppt

Effects on the Human Body § 1 m. A: Can Be Felt By The Effects on the Human Body § 1 m. A: Can Be Felt By The Body § 2 -10 m. A: Minor shock, May result in a fall § 10 -25 m. A: Loss of Muscle Control, May Not Be Able To Let Go Of The Current § 25 -75 m. A: Painful, May Lead to Collapse or Death § 75 -300 m. A: If Lasts for more than ¼ Second, Almost Always FATAL Engineering-43: Engineering Circuit Analysis 7 Bruce Mayer, PE [email protected] College. edu • ENGR-43_Lec-01 a_Electrical_Safety. ppt

Body’s Resistance § Skin Offers Most Of The Body’s Electrical Resistance § Increased Resistance Body’s Resistance § Skin Offers Most Of The Body’s Electrical Resistance § Increased Resistance • Thick and Callused Skin (Foot or Hand) • Dry skin § Decreased resistance • Thin Skin (Inner Forearm) • Wet or Sweaty Skin • Broken or Abraded Skin (Scratches) Engineering-43: Engineering Circuit Analysis 8 Bruce Mayer, PE [email protected] College. edu • ENGR-43_Lec-01 a_Electrical_Safety. ppt

Resistance Varies § Different levels of electrical resistance for each person § Ranges from Resistance Varies § Different levels of electrical resistance for each person § Ranges from 500 ohms to many thousands of ohms § The greater the body’s resistance, the less chance of harm § A similar voltage shock can be minor to one person and deadly to another. Engineering-43: Engineering Circuit Analysis 9 Bruce Mayer, PE [email protected] College. edu • ENGR-43_Lec-01 a_Electrical_Safety. ppt

Additional Resistance § Gloves § Shoes § Mats Engineering-43: Engineering Circuit Analysis 10 Bruce Additional Resistance § Gloves § Shoes § Mats Engineering-43: Engineering Circuit Analysis 10 Bruce Mayer, PE [email protected] College. edu • ENGR-43_Lec-01 a_Electrical_Safety. ppt

Hazard Control § Electrical Systems Are Inherently Safe § Injuries Typically Occur When: • Hazard Control § Electrical Systems Are Inherently Safe § Injuries Typically Occur When: • Procedures Are Inappropriate • Procedures Are Not Followed Or Ignored • Safety Systems Are Circumvented 1866 - Werner Siemens (1816 -1892) perfects the dynamo, a generator in which part of the generator's working current is used to power the field windings, eliminating both the need for permanent magnets and one of the basic limits to generating electric power Engineering-43: Engineering Circuit Analysis 11 Bruce Mayer, PE [email protected] College. edu • ENGR-43_Lec-01 a_Electrical_Safety. ppt

General Electrical Hazards § High-voltage overhead power lines § Damaged insulation on wires § General Electrical Hazards § High-voltage overhead power lines § Damaged insulation on wires § Digging or trenching near buried lines § Broken switches or plugs § Overloaded circuits § Overheated appliances or tools § Static electricity § Flammable materials Engineering-43: Engineering Circuit Analysis 12 Bruce Mayer, PE [email protected] College. edu • ENGR-43_Lec-01 a_Electrical_Safety. ppt

Portable Power Tools § Inspect Portable Corded Power Tools § Never Use Damaged Equipment Portable Power Tools § Inspect Portable Corded Power Tools § Never Use Damaged Equipment • Tag it out of service • Have it repaired or replaced § Never Use Portable Power Equipment In Wet Or Damp Areas § Stop Using Power Tools If They Become Hot Or Start Sparking Engineering-43: Engineering Circuit Analysis 13 Bruce Mayer, PE [email protected] College. edu • ENGR-43_Lec-01 a_Electrical_Safety. ppt

Extension Cords § Inspect And Check For Capacity § For Temporary Work only § Extension Cords § Inspect And Check For Capacity § For Temporary Work only § Do Not Use As A Rope To Pull Or Lift Objects § Should NOT Be Fastened With Staples or Hung Over Hooks Engineering-43: Engineering Circuit Analysis 14 WHY? Bruce Mayer, PE [email protected] College. edu • ENGR-43_Lec-01 a_Electrical_Safety. ppt

Electrical Cord Inspection § § Deformed or Missing Pins Damaged Outer Jacket Or Insulation Electrical Cord Inspection § § Deformed or Missing Pins Damaged Outer Jacket Or Insulation Evidence of Internal Damage If Damaged, Take Out Of Service Until Repaired NEVER remove or bypass the ground pin on a three-pronged plug in order to insert it into a non-grounded outlet. Engineering-43: Engineering Circuit Analysis 15 Bruce Mayer, PE [email protected] College. edu • ENGR-43_Lec-01 a_Electrical_Safety. ppt

Circuit Protection § Energize or De-energize With Appropriate Switches, Breakers, etc. § Do Not Circuit Protection § Energize or De-energize With Appropriate Switches, Breakers, etc. § Do Not Energize Or De-energize With Fuses, Terminal Lugs, Or Cable Splice Connections § If Circuit Protection Device Is Tripped - inspect Engineering-43: Engineering Circuit Analysis 16 Bruce Mayer, PE [email protected] College. edu • ENGR-43_Lec-01 a_Electrical_Safety. ppt

Grounding Equipment § Most Electrical Equipment Is Designed With A Grounding System § Do Grounding Equipment § Most Electrical Equipment Is Designed With A Grounding System § Do Not Use Equipment With Damaged Grounding Connectors § Do Not Use Adapters That Interrupt The Grounding Connection SP-1001 Ground Monitor/Ground Point • Verifies electrical ground • Ground point for wrist straps • Ground point for ground cords with banana plugs • Provides surge protection Engineering-43: Engineering Circuit Analysis 17 Bruce Mayer, PE [email protected] College. edu • ENGR-43_Lec-01 a_Electrical_Safety. ppt

Ground Fault Circuit Interrupters § GFCIs Reduce The Likelihood Of Fatal Shocks § Detect Ground Fault Circuit Interrupters § GFCIs Reduce The Likelihood Of Fatal Shocks § Detect Small Amount Of Earth Current And Automatically Switch Off Power § Used With Extension Cords And Portable Tools § Standard Fuses and Circuit Breakers Protect EQUIPMENT, NOT PEOPLE Engineering-43: Engineering Circuit Analysis 18 Bruce Mayer, PE [email protected] College. edu • ENGR-43_Lec-01 a_Electrical_Safety. ppt

What To Do In An Electrical Storm § NOTE: Lightning surges from the clouds What To Do In An Electrical Storm § NOTE: Lightning surges from the clouds to the ground along the best conductor around, which is usually the HIGHEST object: DON'T BE THAT CONDUCTOR! § If you are OUTSIDE in a storm, do this: • Seek SHELTER, preferably a house. • Get in your VEHICLE. • If in the open, seek LOW ground; Sit or Lie DOWN Engineering-43: Engineering Circuit Analysis 19 Bruce Mayer, PE [email protected] College. edu • ENGR-43_Lec-01 a_Electrical_Safety. ppt

Electrical Storm → DON’Ts § Do NOT Associate Yourself with an Electrical Conductor or Electrical Storm → DON’Ts § Do NOT Associate Yourself with an Electrical Conductor or be the Highest Point • On a golf course, don't continue to play, and never hold a metal club in your hand. • Don't swim. If you are in the water, get out! • If you are in a boat, get to land! • Stay away from metal objects that are lightning conductors. • Don't stand under a tree. Instead of providing shelter, a wet tree can attract lightning. • Never stand out in the open during a storm. Engineering-43: Engineering Circuit Analysis 20 Bruce Mayer, PE [email protected] College. edu • ENGR-43_Lec-01 a_Electrical_Safety. ppt

Summary § Electricity Will Try To Reach Ground Even If It Means Going THROUGH Summary § Electricity Will Try To Reach Ground Even If It Means Going THROUGH A PERSON § Even the “Small” Voltage From Your Home Can Cause Serious Injury § Always Inspect Power Tools And Cords And Do Not Use Them If Damaged § Do Not Attempt To Repair Electrical Equipment Unless Trained & Qualified Engineering-43: Engineering Circuit Analysis 21 Bruce Mayer, PE [email protected] College. edu • ENGR-43_Lec-01 a_Electrical_Safety. ppt