ELECTRICAL HAZARDS
307.
307. What What are are the the Electrical Electrical hazards? hazards?
Shock, Burn, Electric sparks that can cause ignition of flammable Shock, Burn, Electric sparks that can cause ignition of flammable mixtures, explosion etc., are the electrical hazards.
mixtures, explosion etc., are the electrical hazards.
308.
308. At At what what current current a a person person can can withstand? withstand?
1mA
1mA to to 8mA 8mA - - Person Person can can withstand.withstand.
Greater
Greater than than 75mA 75mA - - Cause Cause death.death.
Tissue will burn when current greater than 200 mA and greater.
Tissue will burn when current greater than 200 mA and greater.
309.
309. Before doing Before doing the the electrical jelectrical job ob what what to to check check first? first?
Always test a circuit to make sure it is de-energized by using proper Always test a circuit to make sure it is de-energized by using proper PPE, before working on it.
PPE, before working on it.
310.
310. What What do do you you do do when when co-worker co-worker get get shocked? shocked?
Call other people for help Call other people for help
Shut off the power supply to the particular circuit.
Shut off the power supply to the particular circuit.
Do not touch the victim.
Do not touch the victim.
Pry the victim with non-conductor (wood) Pry the victim with non-conductor (wood) Call emergency medical team.
Call emergency medical team.
311.
311. How How to to avoid avoid electrical electrical hazards? hazards?
Prevent overloading by using correct size and type wire.
Prevent overloading by using correct size and type wire.
Prevent exposure of live wire. (provide proper insulation) Prevent exposure of live wire. (provide proper insulation) Prevent exposure of live electrical equipments/parts.
Prevent exposure of live electrical equipments/parts.
Lock out and tag out circuits and machines before Lock out and tag out circuits and machines before maintenance.
maintenance.
Prevent electrical shock by grounding tools while working on Prevent electrical shock by grounding tools while working on it.
it.
Prevent too much current in circuits by using over current Prevent too much current in circuits by using over current protection devices.
protection devices.
312.
312. What What are are the the common common ignition ignition hazards hazards in in petrochemical industry petrochemical industry electrical equipment?
electrical equipment?
Motors, switches & breakers, lamps, cable joints, junction & terminal Motors, switches & breakers, lamps, cable joints, junction & terminal boxes, welding cables etc.,
boxes, welding cables etc.,
313.
313. What What is is an an electrical electrical sparks? sparks?
When electricity jumps a gap in air, it is called a spark.
When electricity jumps a gap in air, it is called a spark.
314.
314. Are Are all all electrical sparks electrical sparks or or arcs arcs hot hot enough enough to to ignite ignite petroleum petroleum products?
products?
Most of
Most of them. them. But there But there are certain are certain electrielectrical devices cal devices which mwhich mayay create sparks or arcs
create sparks or arcs that are that are too weak to too weak to cause ignition. cause ignition. The flashThe flash light switches or thermocouple switches are examples of this type. It light switches or thermocouple switches are examples of this type. It is however, to be remembered that the intensity of the spark does is however, to be remembered that the intensity of the spark does not depend on the switch but on the amount of current flowing the not depend on the switch but on the amount of current flowing the circuit.
circuit.
315.
315. Can the Can the flash light flash light bulb bulb ignite a ignite a flammable mixture flammable mixture if if exposed? exposed?
Yes.
Yes. If the If the hot-glowihot-glowing ng filament is exposed filament is exposed due to due to a broken a broken glassglass bulb, a fire can start in a flammable mixture.
bulb, a fire can start in a flammable mixture.
316.
316. How are How are the the lamps lamps protected from protected from causing causing ignition in ignition in the plant the plant area? area?
Lamps are provided with vapor tight fittings that is, even if the bulb Lamps are provided with vapor tight fittings that is, even if the bulb breaks and the
breaks and the hot filament is exposed hot filament is exposed momentarily, there will momentarily, there will be nobe no fire or explosion since vapors are present inside the glass globe.
fire or explosion since vapors are present inside the glass globe.
317.
317. What What is is the the meaning meaning of of an an explosion explosion proof proof fittings? fittings?
An explosion proof fitting is designed to withstand the pressure An explosion proof fitting is designed to withstand the pressure created by a internal explosion & to cool hot gases below the ignition created by a internal explosion & to cool hot gases below the ignition temperature before they reach outside of the explosion proof temperature before they reach outside of the explosion proof housing.
housing.
318.
318. What is What is the the basis basis of of the the selection selection of eof explosion xplosion proof proof electrical electrical equipment in petrochemical industries?
equipment in petrochemical industries?
Likewise, electrical equipments are classified into two types.
Likewise, electrical equipments are classified into two types.
Equipment which creates sparks is arcs as a result of normal use.
Equipment which creates sparks is arcs as a result of normal use.
Example:
Example: An An ordinary ordinary light light switch.switch.
Equipment which create sparks only when there is a failure Equipment which create sparks only when there is a failure Example: The common induction motor.
Example: The common induction motor.
All electrical equipment in continuously hazardous areas must be All electrical equipment in continuously hazardous areas must be explosion proof.
explosion proof.
319.
319.