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Electrical Safety

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Introduction

� What percentage of American workforce is injured by electrocution each year?

• 9%

Note: Based on Bureau of Labor and Statistics

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Electrical Safety

� What is the most widely used form of energy in most facilities?

• Electricity

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Introduction

� What are the Michigan rules regarding electricity?

• Part 39-Design Safety Standards for Electrical Systems

• Part 40-Electrical Safety-related Work Practices

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Voltages

� What is the most common voltage used in the Hospital setting?

• Most Hospital equipment is set up for 115 (120) volts for most plug-in devices.

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Electrical Hazards

� What does 29 CFR 1910.303(b)(1) state?• 29 CFR 1910.303(b)(1) requires that

”Electrical equipment shall be free from recognized hazards that are likely to cause death or serious physical harm to employees” .

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Electrocution

� A current between _____ and ______ milliamperes can cause ventricular fibrillation in the heart.• 70 and 200 milliamperes

� What is a miliampere?• A milliampere is 1/1000 of an ampere.

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Ventricular Fibrillation

� Ventricular fibrillation can happen due to a small current passing through the body in what two ways?

(a) from head to foot or (b) from hand to foot and thru the heart

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Electrocution

� How many mAs will it take to cause ventricular fibrillation?• 100 mA to cause ventricular fibrillation

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Voltage Define voltage:

The amount of electrical force (electromotive force).

Name the measurement between two points. This can be between “hot” and neutral or between other charged items.

Potential

What is voltage measured in?

Volts

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Voltage

� What is used for the stated voltage for a given line? (Example: a 115 volt circuit may actually be 120 volts, but is called 115 volts nominal).• Nominal

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Current

� What are two different types of current?• AC-Alternating current

• DC-Direct current

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Current

� What is the amount of electricity that flows in a circuit?• Current

� What is current measured in?• Amperes (Amps)

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AC and DC

� What does most existing equipment run on?• AC and DC

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Resistance

What opposes (uses) the flow of current measured in Ohms (R).

Resistance

What two ways is this caused?

Either by the nature of the material or work done.

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Ground

What is the process of achieving earth neutral?

Grounding

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Ground

� What is the symbol for ground?

� Where is it found?• May be found on the back panels of

equipment.

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GFCI

� What prevents electrocution by detecting a ground fault and opening the circuit up?• Ground Fault Circuit Interrupter

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Overcurrent

� What is the extra amount of current that passes through a circuit and an protection device that usually opens the circuit.• Overcurrent

� What are these devices?• usually circuit breakers or fuses.

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Overcurrent Protection

� How does a fuse or breaker work?• the extra amount of amperage will cause a

conductor to get hot and either “blow” or move to open an overloaded circuit.

� What are two examples of things that have fuses or breakers?• You have fuses or breakers in your house

and car.

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Short Circuit

� What happens when there is a direct contact between “hot” and “neutral”.• Short Circuit

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Static Electricity

� What is the buildup of the difference of potential between materials?• Static Electricity

� Static electricity is ____ in voltage but ___ in amperage (in most cases).• High in voltage, but low in amperage

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Extension Cords

� In what situations does 1910.305(g)(1)(iii) not allow flexible cords to be used?• As a substitute for fixed wiring

• Running through wholes

• Running through doorways, windows, etc.

• Attached to building surface

• Behind walls, ceiling, or floors

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Temporary wiring:

� What amount of time does 1910 305(a)(2) require that temporary wiring be used for?• For a maximum of 90 days for decoration

and like items.

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Grounded Equipment

� What are two guidelines to follow when plugging a piece of equipment in?• Never use a plug that the ground prong is

broken off.

• Always check before plugging into a receptacle.