Electrical safety Flashcards
What are the standards for electrical safety
CNEC - Canadian National Electrical Code
OEC - Ontario Electrical Code
Why is electrical energy a hazard
it can act as both a source of heat or spark of ignition of a fuel which can subsequently develop into a fire
Why is electricity a hazard to humans
because human tissue is primarily water and water is an excellent conductor of electricity. tissues can very easily be damaged if electrical contact is made
where does electricity travel and what is its normal route
in closed circuits and via conductor
What is electrical shock
when the body becomes part of the circuit
Electrical shock occurs When an individual is in contact with the ground and contacts what 3 things
both wires of an electrical circuit
1 wire of an energized circuit and ground
metallic part that has become energized by contact with conductor
When do metal parts of electric tools become energized
If there is a break in the insulation of the tool or machine wiring
What does the breakdown in insulation or short circuiting to ground result in
material degradation
heat buildup
ignition if electrical arc intensity is sufficient to initiate combustion
What are the 3 hazard classifications for electrical equipment
class 1: flammable liquids and gases Div 1: present in some form Div 2: not normally present class 2: combustible and or conducting dusts class 3: fibers and lint
It is okay to use electrical equipment for 1 type of class for another. true or false
false
List areas of electrical equipment
electrical rooms: HVAC
computer and data center
switchyards and switchrooms: (transformers and capacitors)
Electical operated equipment
What does the CEC provide
basic technical guidance framework for all canadian jurisdictions to follow when it comes to overall safety relating to electrical systems in buildings
What is the CEC equivalent to
US NEC
What are the 3 types of hazardous locations as per NEC
Class 1 - one which is created by the presence of flammable gases or vapors in the air (natural gas or gasoline vapor) in sufficient quantities to be explosive or ignitable
Class 2 - areas made hazardous by the presence of combustible dust. finely pulverized material suspended in atm can cause powerful explosion as one in a petroleum refinery
Class 3 - areas where easily ignitable fibers are present due to the types of materials being handled, stored or processes. fibers are not suspended in air but collect around machinery or light fixtures where heat can ignite them
List examples of class 1 hazardous locations
petroleum refineries
spray finishing areas
dry cleaning planrs
utility gas plants
list examples of class 2 hazardous locations
grain elevators
flour and feed mills
producers of plastics, medicine, fireworks, starch, candies, mg or al powders
coal preparation plants
list examples of class 3 hazardous locations
textile mills
cotton gins or seed mills
flax processing plants
How is static electricity generated
by contact and separation of dissimilar materials
when a fluid flows through a pipe or from a tank opening to another vessel or container
what are the main hazards of static electricity
fire and explosion from sparks containing enough energy to ignite flammable vapors of flowing liquid
what is the primary mean of reducing static electricty hazard
through the use of bonding or grounding when transferring as it prevents static electricity from igniting the gasoline vapors as its being pumped
what is the purpose of grounding
to eliminate potential difference betwen object and earth
what is grounding required for
class 1 flammable liquids
Which materials can accumulate significant static charges? are they easily dispersed?
plastics (synthetic materials) and no
When are objects said to be well bonded
when their charges flow freely between them and with no difference in charge exists between them
Will bonding eliminate a static charge?
no
what will bonding do
equalize the potential between the bonded objects so that a spark/arc wont occur
When is bonding achieved
when there is a physical connection with a bond wire between 2 conductive objects in order to eliminate static charge potential difference
When must one provide a bond wire and when is it unnecessary
between containers during flammable liquid filling operations UNLESS a metallic path between them is present
Will bonding eliminate the different in potential between objects and earth?
NO unless one of the objects is connected to earth using a ground wire
List some electrical equipment defects
vibration of electrical conneftions
floor leakage where wiring is exposed to waters, oils, alkalis, etc
insulation deterioration and damage
rodents
cable trays and passages containing multiple services
cable coverings wear and tear
Is causation of fire by electrical source complex or simple
simple
what can causation involving electrical energy and equipment be attributed to
operating ourside design and installation standards
misuse of equipment
failure to inspect and maintain
List some electrical fires causation
overloading circuits
suspended lights in contact with combustible ceilings or other material
faulty ballast - overheating
dirty motors
improper flammable liquid storage
computer rooms
protable electrical equipment in hazardous areas
Which section of NFPA deals with electrical safety
NFPA 70E
What are GFCI
a device that protects a worker from dangerous electrical shock by detecting a ground fault almost instantaneously before the fault has the opportunity to be compelted with any current of significance.
How fast does a GFCI shut off the electricity flow in the case of a ground fault
1/40 of a second
where does a GFCi detect differences in current
ordinary household wires - black and white circuit wires
What are clues that an electrical hazard exists
tripped circuit breaker or blown fuse
warm tools, wires, cords, connections or junction boxes
GFCI shuts off a circuit
worn/frayed insulation around wire or connection
What is the ESA
Electrical Safety Authority
not for profit organization that is set up to administer the ESC in Ontario
What does the ESA provide
annual reports on status of electrical safety in province
