1 Electrical Safety

2 Electrical Hazards & OSHA 29 CFR (b)(1) requires: “Electrical equipment shall be free from recognized hazards that are likely to cause death or serious physical harm to employees” Michigan has adapted the appropriate OSHA regulations

3 Electrocution Each year, ~9% of fatalities in American workforce is by electrocution while working around electricity. Workplace electrocution hazards: Broken light bulb Frayed cords Exposed wires Water around electrical equipment Crowded outlets

4 Voltage  Voltage: amount of electrical force (electromotive force) to move electricity between 2 points  This is difference of electron and proton potential.  Measurement between 2 points can be between “hot” and neutral, or between other charged items  Voltage measured in volts

5 VOLTS RMS One Cycle Hot Neutral

6 Resistance  Resistance: measure of opposition of flow of current (opposite of conduction)  Measured in Ohms (Voltage/Current)  Similar to friction  Caused by nature of material or work done  Example: A toaster wires get hot due to resistance.

Safe Electrical Work Practices Checked for frayed cords Wear correct PPE Use correct tools Turn off unused machines Use non-conducting ladders No water around electrical equipment Grounding 7

8 Current  Current: amount of electricity that flows in a circuit  Measured in amperes (Amps)  Milliamp = 1/1000 of amp

9 Current There are 2 different types of current:  AC- Alternating current (outlets)  DC- Direct current (batteries)

10 V fib means heart loses meaningful pumping action, thus causing death in a short period of time. This happens when a small current passes either (a) from head to foot, or (b) from hand to foot and thru the heart. Ventricular Fibrillation ~100 milliamperes can cause VF Current between milliamperes, if passed through heart, can cause ventricular fibrillation.

11 Grounding  Ground: Process of achieving earth neutral  Common (wired) return path for electrical circuit to ground

12 GFCI Ground Fault Circuit Interrupter  Prevents electrocution by detecting a ground fault and opening circuit (so our body doesn’t become part of circuit)  A type of undercurrent  Use: kitchen, bathroom, basement, garage, outside, laundry room  Activates at 5-61 mA and 1/25 of second

13 GCFI-Receptacle

14 Grounded Equipment Never use a plug with a missing ground prong. Always check before plugging into a receptacle.

15 Overcurrent Overcurrent - extra amount of current that passes through a circuit Overcurrent protection device opens the circuit (electricity won’t flow) These devices are circuit breakers or fuses.

16 Short Circuit A short circuit is when there is a direct contact between “hot” and “neutral”.

17 Static Electricity Static electricity - buildup of difference of potential (electric charge) between materials E- move from one object to another when surfaces come into contact (friction) Can ignite vapors Positive  Negative

18 Extension Cords  Extension cords cannot be used:  As a substitute for fixed wiring  Running through holes  Running through doorways, windows, etc.  Behind walls, ceiling, or floors  Should contain warning labels & rating info (& only be used temporarily)

Polarized Plugs One prong slightly wider so can only be inserted one way Allows live and neutral connection safety 19