1. ELECTRICAL SAFETY
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end NOTES
Today we are going to talk about electrical safety. ▼

2. Electricity - a hazard path of least resistance
Electricity is a hazard only when YOU become part of a “live” circuit. Electrical current will always return to the ground. Current will flow through a person if he or she is the path of least resistance.
There are several ways you can be exposed to electricity in a shop, as well as at home. ▼

3. “Live” Electrical Circuits
Exposed “live” wires:
Electrical cords
Electrical outlets
Electrical panels
Energized tools or vehicle parts
Hybrid batteries
You are near “live” electrical circuits every time you are around ▼
exposed “live” wires such as:
Damaged electrical cords
Electrical outlets with missing parts or knockouts
Electrical panels with uncovered openings ▼
Energized tool or vehicle parts ▼
and hybrid batteries ▼

4. Hazardous situations Using electrical tools when water is present
Performing electrical work standing on metal ladders
Handling metal objects that can contact “live” wires
Being in or around vehicles in contact with “live” powerlines
There are also hazardous situations that increase your risk of being electrocuted : ▼
Using electrical tools when water is present on the floor or in the air ▼
Performing electrical work while standing on metal ladders ▼
Handling metal objects that may come in contact with “live” wires ▼
Being in or around vehicles in contact with damaged powerlines that are still “live”. ▼ ▼

5. Health Effects Electrocution (fatal)
Electric shock (muscle contractions, blood clots, nerve damage)
Burns (from electric arc, or burning clothes or objects)
Other injuries caused by falls due to shock or muscle contractions (fractures, torn ligaments)
When you are exposed to electrical current, a number of outcomes are possible: ▼
Electrocution – which is fatal.
1 in 3 deaths are caused by contact with electricity at 120V. This is the voltage of most outlets in collision shops, as well as in your home. ▼
Electric shock can cause muscle contractions, blood clots and nerve damage. ▼
Burns can occur from an electric arc, or from burning clothes or other objects ▼
Other injuries such as bone fractures and torn ligaments may be caused by falls due to shock or muscle contractions. ▼

6. Health Effects Current intensity (amps) Current path through the body
Skin condition: wet or dry
Duration of exposure
The severity of health effects due to exposure to electricity depends on: ▼
Current intensity, measured in Amperes or amps ▼
Current path through the body. The most dangerous currents are the ones passing through the chest and head. ▼
Skin condition – wet or dry. The damage is much greater when skin is wet. ▼
Duration of exposure to electricity. The longer you are exposed the more severe the damage. ▼
It’s not the voltage that kills you, it’s the amperage! ▼
It’s not the voltage that kills you, it’s the amperage!

7. 1 second @ 120 Volts Current Reaction 15 A 10 A
cardiac arrest; death probable
1-4.3 A
nerve damage occurs; death likely mA
extreme pain; breathing stops;
ventricular fibrillation
6-30 mA
painful shock; muscles freeze;
may not be able to let go of live circuit
5 mA
slight shock
1 mA
faint tingle
< 1 mA
not perceptible
breaker trips
3-4 min to
“brain dead”
GFCI trips
Let’s see what happens when the human body is exposed to various currents for 1 second, at 120 Volts, the common household voltage.
Currents up to 5 milliamps are perceived as a slight tingle or shock. ▼ 5mA is the value at which a GFCI trips and interrupts the circuit. GFCIs are designed to protect people.
Currents up to 30 milliamps deliver a painful shock and can trigger muscle freeze. If that happens, a person may not be able to let go of the live circuit. ▼
Currents between 50 and 150 milliamps inflict extreme pain and may trigger ventricular fibrillation. This is when the heart beats rapidly but oxygenated blood does not reach the brain. ▼ Brain death occurs in 3-4 minutes. Normal heart rhythm is re-established by initiating defibrillation using an AED, Automated External Defibrilator.
All currents above 1 Amp have the potential to cause immediate death. ▼
A circuit breaker trips at a minimum current intensity of 15 Amps. Breakers are designed to protect electrical equipment from damage.
Now let’s look at the current intensity of some tools you use in the shop. ▼

8. Electrical Currents in the Shop
portable welder
up to 235 A
15 A
up to 15 A
10 A
1-4.3 A
4.2 A
500 mA mA
5 mA
shop vacuum
GFCI trips
ventricular
fibrillation
breaker trips
death likely
Makita buffer
Makita 5” disc sander
fluorescent lights
First, let’s keep in mind the key health effects: ▼
Ventricular fibrillation occurs from 75 to 150 milliamps and death is likely after exposures to currents of 1 to 4.3 Amps. Remember that a GFCI trips at 5 milliamps and a breaker at 15 Amps.
Now let’s look at how much amperage common tools need to operate. ▼
Florescent lights: 500 milliamps
DISCUSSSION: Is it safe to change the ballast without turning off the lights AND putting the circuit breaker in OFF position?
-----
No. As you’ve seen in the previous slide, when ventricular fibrillation occurs, brain death follows in 3 or 4 minutes.▼
A Makita 5 inch disc sander: 4.2 Amps ▼
A Makita buffer: 10 Amps ▼
A shop vacuum: up to 15 Amps ▼
And a portable welder can draw up to 235 Amps! ▼
Now you understand WHY contact with any exposed wires on a running tool has the potential to kill you. ▼

9. Precautions – Electrical Cords
Report electrical cords that have:
loose plugs
missing ground prongs
damaged insulation
To avoid accidents involving electricity, several precautions can be taken.
At school, report electrical cords that have: ▼
Loose plugs ▼
Missing ground prongs ▼
or Damaged insulation ▼

10. Electrical Cords – DO NOT:
Repair using tape
Splice
Remove grounding pin
Do not repair electrical cords using tape of any kind
Do not splice electrical cords
Do not remove grounding pin ▼

11. Electrical Tools - DO NOT:
Use if you get shocked or the breaker trips repeatedly
Operate while holding against your chest, arm, or leg
Repair or troubleshoot while the tool is plugged in
Pull by the cord when unplugging
Carry by the cord
When it comes to electrical tools, DO NOT:▼
Use if you get shocked or the breaker trips repeatedly ▼
Operate while holding against your chest, arm, or leg ▼
Repair or troubleshoot while the tool is plugged in ▼
Pull by the cord when unplugging ▼
Carry by the cord ▼

12. Precautions - Electrical Panels
No unguarded openings
Door closed at all times
Clear access
Electrical panels can be a source of sparks and arcs, which could start a fire.
To prevent such incidents: ▼
There should be no unguarded openings. ▼
The electrical panel door should be securely closed at all times. ▼
Access to electrical panels should be kept clear. ▼

13. Precautions – Wet Areas
Wear insulated footwear when operating electric tools
Avoid standing in water
Use only GFCI-protected outlets
Permanently installed
Portable
In areas where water is present: ▼
Be sure to wear insulated footwear when operating electric tools. ▼
Avoid standing in water. ▼
Use only GFCI-protected outlets. GFCIs can be: ▼
permanently installed. As you see here multiple outlets can be wired to ONE ground wire ▼
or they can be portable. ▼
Always test GFCIs with a tool plugged in and running! Wiring errors have caused fatal accidents. ▼
Test GFCIs with a tool plugged in and running!

14. Precautions – Hybrid Batteries
Wear Class 0 rubber insulated gloves (lineman’s gloves)
Follow manufacturer’s instructions for disconnecting the battery
Test for stray currents
Wait at least 10 min before working on the vehicle
red label
To avoid electrocution when working with hybrid vehicle batteries: ▼
Wear Class 0 rubber insulated gloves, lineman’s gloves. ▼
Follow manufacturer’s instructions for disconnecting the battery ▼
Test for stray currents ▼
Wait at least 10 minutes before working on the vehicle ▼
In the assigned homework you will learn more about lineman’s gloves.
DISCUSSION: Tell students what the expectations are while in school and if they will receive additional training on working with hybrid batteries.

15. In Case of Emergency Turn off the electrical current Call 911
Do not touch the victim if still in contact with the “live” circuit!
Pry the victim from the energized circuit using non-conducive materials (broom wood handle, plastic vacuum cleaner tube, PVC pipe)
Do not move the victim
Use a defibrillator (AED) if the victim is breathing but has rapid irregular heart rhythm
Perform CPR if the victim is NOT breathing and you’ve been trained
DISCUSSION: Tell students what they are expected to do in case of emergency – THEN show slide content: ▼
Turn off the electrical current ▼
Call 911▼
Do not touch the victim if still in contact with the “live” circuit! ▼
Pry the victim from the energized circuit using non-conducive materials (broom wood handle, plastic vacuum cleaner tube, PVC pipe) ▼
Do not move the victim ▼
Use a defibrillator (AED) if the victim is breathing but has rapid irregular heart rhythm. The nearest AED is located _______________________ ▼
Perform CPR if the victim is NOT breathing and you’ve been trained ▼

16. Summary Contact with “live” wires can be potentially fatal
Avoid using electric tools in wet environments, with wet hands, or when perspiring heavily
Report all damaged cords, outlets, tools
GFCIs protect YOU – test them!
Know what to do in case of emergency
In summary: ▼
Contact with “live” wires can be potentially fatal. ▼
Avoid using electric tools in wet environments, with wet hands, or when perspiring heavily. ▼
Report all damaged cords, outlets, or tools to your instructor ▼
Circuit breakers protect the equipment.
GFCIs protect YOU – test them! ▼
Know what to do in case of emergency and what is expected of you. ▼
And remember:
It’s not the voltage that kills you, it’s the amperage! ▼
It’s not the voltage that kills you, it’s the amperage!

17. Questions?
Do you have any questions?