CFD Electrical Safety Flashcards
Voltage
Difference in electrical potential between two point in a circuit
Force that causes the flow of electricity and is measured in volts
Compared to water pressure
Current
Flow of electrical charge
Compared to the rate of flow of water in a pipe
Resistance
Similar to the effect of friction on the flow of water in a pipe
Insulators
very high resistance materials
Ex. Porcelain, glass and plastic
Conductors
the low resistance materials
Ex. Metals
Grounding
process of mechanically connecting isolated wires and equipment to the earth
Two conditions that cause the majority of electrical fires
arcing and overheating
arcing
sudden flash of electricity between two points of contact
overheating
overloading of electrical conductors and motors
safe limits approach
until the local electrical utility verifies the voltage, emergency responders must maintain a safe clearance distance of 7m
electricity takes all paths to the ground
more current will flow through the path of least resistance
step potential
Refers to the risk of electrocution based on the possible voltage running through the ground
If you were to place one foot near the point of ground contact and your other foot a step away, the difference in voltage would cause electricity to flow up one leg, through the abdomen and back down the other leg
Touch potential
Similar to step potential, electricity would flow through your body if you were to place your hand on an energized source while your feet we at some distance from the source
Effects of electricity on the body
Dependent on the amount of current and the length of time the body is exposed to it
The path of electricity through the body is also critical
Medical follow up
Effect can be delayed up to 24 hours
Even a short exposure to electricity can cause an irregular heart rhythm resulting in death within hours
Fallen or low hanging wires
A distance of at least 10m or more is recommended from the down wire or conductive object it is in contact with
Getting out of a vehicle
Contacting the car and ground at the same time can be Fatal
Shuffle step or hop (keep feet together)
Using water on electrical fires
There should be a minimum of 700kpa at the nozzle
The fog spray should be set to 30 degrees fog pattern
FF must be at least 10m aware from energized source
Solid bore, straight stream and foam should all be avoided
Further electrical resistance of the ground can change due to water run-off
Overhead power lines near buildings
Initial minimum 7m from working zone
Radiofrequency (RF) Radiation
Two areas of the body, the eyes and the testes, are particularly vulnerable to RF heating because of the relative lack of available blood flow to dissipate the excessive heat load
