Electrical Safety

Kellogg community college, INEL 05010

The danger of shock from a 480 or 240 volt a.c. power system is well recognized by operating personnel is shown by the relatively few reports of serious shock received from these voltages despite their widespread use. On the other hand, numerous fatalities are reported every year due to contact with ____?

110 -120 volt circuits

Despite a fairly widespread, but totally unfounded, popular belief to the contrary, voltage in the _____-_____ volt range and below are very dangerous and can cause death.

110-120V

Voltages as low as _____________ have been known to cause fatal shock.

35 Volts

List three things that are important to safety:

Planning, preparation, neatness

Avoid ________________ with power line voltages.

Body or hand contact

If an accident should occur ______________________________________________.

Shut off electrical power immediately

Current flow through the body of 0.1-0.2 amps causes a fatal heart condition known as ___________________________.

Ventricular fibrillation

After an accident has happened, investigation almost invariably shows that it could have been prevented by the exercise of ____________________________________.

Simple safety precautions

Electricity strikes without _______________________.

Warning

Hurrying reduces ___________________ and invites accidents.

Caution

Taking time to be ________________ saves time in the end.

Careful

Taking _________________ is an invitation to trouble.

Chances

If you don’t know the safe way, it pays to find out before _____________to danger.

Exposing yourself

Every electrical circuit, even as low as ___________ and possibly even lower, is a potential source of danger and must be treated as such.

35 Volts

Except in cases of emergency, never work on an energized circuit and then only if you are qualified to do so. It must be considered that the circuit is ______________ until a personal check has been made to see that the switch is opened and tagged, and the circuit has been tested with a volt meter or voltage tester.

Energized

1. Energized switchboards are a great source of danger. No work should be done on any switch board without first obtaining the approval of ____________________ supervisory personnel.

Qualified

Records show that seven out of ten victims of electric shock were revived when CPR

 was started in less than _______________ after the shock. After 3 minutes the chances of revival decrease rapidly.

3 minutes

Instead of taking time to hunt for a pair of rubber gloves for use in grasping the victim, the victim can be safely pulled free if conditions are dry by grasping them by the a) ___________ __________ or by the b) ___________________. Instead of hunting for a rubber mat to stand on such non-conducting materials as c) ____________________________ laid down on the floor, or a coil of rope will suffice.  In no case during the rescue should the rescuer allow any part of their body to touch a d) ____________________. Such as a bare concrete floor, metal structure or furniture, earth or anything that will place his body in an electrical current path.

A) Slack in clothing

B) Leather of his shoes

C) Linoleum, vinyl tile, blankets or bedding, dry lumber, cardboard, wooden ladder, etc.

Conventional domestic distribution systems such as 230/120 volt, single phase, 3-wire systems that supply most homes and many smaller commercial establishments have a “grounded” neutral. While there is no potential difference or voltage between the _______ _____________ conductors and earth, the shock hazard definitely exists between the ___________________ conductors and the ___________________ conductors and earth or any surface or structure that is grounded to earth.

Neutral, live neutral

Metal enclosing cases, bases, frames, and structural parts of electrical equipment which are not intended or expected to have a voltage on them or to carry a current should be _____________________________.

Grounded

Ground-fault current is that which results from a breakdown of electrical insulation allowing current to flow to the metal case or structure of the equipment. If inherent grounding is not provided in the system, grounding can be satisfactorily accomplished by connecting a conductor from the grounding terminal on the receptacle used to the nearest ___________ _______________________________.

Cold water pipe

Cords should be inspected for physical damages such as tears in the insulation, frayed ends, and the like. The plugs should be checked for worn out prongs (worn out prongs are loose when inserted in the receptacle), for proper type for the voltage they are to be used with, and for proper polarity and connections. Plugs should be __________________ _________ when inserted in the receptacle.

Relatively snug

Extension cords should not be over 25 feet in length unless they are sized sufficiently larger than the equipment cord so as to prevent undesirable ____________________________.

Voltage drops

If the grounded type receptacles have not yet been installed in the spaces where the tool or equipment is to be used, other types of plugs and receptacles may be used if the grounding conductor in the tool or equipment cord is connected to the grounding system by other methods; for example:  by means of a spring clip or by securing the grounding conductor to a _________________________________________

Convenient screw or bolt (grounded)

Receptacle

A device that allows electrical equipment to connect to a power supply, typically featuring slots for plugs.

Used in homes and buildings to provide power to various appliances and devices. Can vary in type, such as standard outlets, GFCI, or USB ports. Safety features may include covers or circuit breakers.

Conductor

A substance that facilitates the movement of electric charge, commonly used in electrical wiring and components. Examples include metals like copper and aluminum.

Circuit Breaker

This safety device protects electrical circuits by stopping the flow of electricity when it detects a fault, such as an overload or short circuit. It can be reset after tripping, making it a crucial component in electrical systems for preventing fires and equipment damage.

All electrical leads are to be considered as being alive until it is positively proven that they are dead. To check a circuit, test the “live” side with a voltmeter or voltage tester, then test the “dead” side with the same device and then, ______________________________.

Retest the “live” side

Portable cables should be carefully selected and maintained. They should be of the proper length and cross-sectional area. Spliced portable cables are extremely dangerous and should not be used unless __________________________________________.

An emergency warrants the risk involved

Fuses are safety devices and should be sued as such. When a fuse is blown, it should be replaced with a fuse of the same rated ______________________________. NEVER SHORT OUT A FUSE.

Voltage and ampere capacity

Fuses larger than 10 ampere rated capacity should be removed or replaced only when the circuit is a) _____________________. After the replacement, the circuit should be energized only when the cover over the fuses is b) _______________________________. Neglect of this precaution had=s led to injuries caused by explosion of a fuse when the circuit was energized.

A) Completely de-energized

B) Closed

When checking to see whether circuits are de-energized, never forget to check __________ _________________ circuits as well as power circuits.

Metering and control

Circuits to be overhauled or repaired should be de-energized by opening all switches through which the power could be supplied, and the circuit should be tested with a voltmeter or voltage tester. These switches should be tagged:  “WARNING: DO NOT ___________________________________________.

Change position of switch except direction of (NAME)…

When considerations require that electrical repair or maintenance work be performed, but prohibit de-energizing the circuits involved, extreme measures of precaution must be used. The work should be accomplished only by ______________________________________.

Adequately supervised personnel fully cognizant of the dangers involved

Provide ______________________ illumination.

Ample

The person doing the work should not wear wrist watch, rings, watch chain, metal articles, or loose clothing which might make accidental contact with live parts or which might accidentally catch and throw part of their body into contact with _____

Live parts

Insulate the work from ____________________ by means of insulating material covering any adjacent grounded metal with which you might come in contact.

Ground

Cover working metal tools with _____________________ tape (not friction tape) as far as practicable.

Insulating rubber

Insofar as practicable, provide _______________________ between the work and any live metal parts immediately adjacent to the work to be done.

Insulating barriers

Use ______________________ hand in accomplishing the work, if practicable.

Only one

A rubber glove should be used on the hand not used for handling tools. If the work being done permits, __________________________ should be worn on both hands.

Rubber gloves

Have someone stationed by __________________, and telephoned manned if necessary, so that the circuit or switchboard can be de-energized immediately in case of emergency.

Circuit breakers or switches

A person qualified in ____________________ for electric shock should be immediately available while the work is being done.

First aid

Energized switchboards are a great source of danger. No work shall be undertaken on energized switchboards without first obtaining the _______________________.

Approval of your supervisor

In case of an electrical fire, what are the three steps:

A) De-energize the circuit or equipment affected

B) Report the fire

C) Extinguish the fire with carbon dioxide (or other approved extinguishing agents