BASIC ELECTRONICS - OD1633 - LESSON 1/TASK 1
equipment which you have not been specifically authorized to handle.
Particularly, stay clear of electrical equipment opened for inspection,
testing, and servicing.
Covers for all fuse boxes, junction boxes, switch boxes, and wiring
accessories should be kept closed.
Any cover which is not closed, or is
missing, should be reported to the technician responsible for its
maintenance.
Failure to do so may result in injury to personnel and/or
damage to equipment in the event accidental contact is made with exposed
live circuits.
a. Electrical Fires.
Carbon dioxide (CO2) is the main firefighting
agent used in electrical fires.
However, potassium chloride or purple K
(PKP) is also used to fight electrical fires, because it is a noncorrosive
agent.
In other words, CO2 will corrode electrical circuits and PKP will
not. Both substances are nonconductive and, therefore, are safe to use in
terms of electrical safety.
If, however, the horn of a CO2 fire
extinguisher is allowed to come in contact with an energized electrical
circuit, an electrical shock may be transmitted to the person handling the
fire extinguisher.
The very qualities which cause CO2 and PKP to be valuable extinguishing
agents also makes them dangerous to life. When they replace the oxygen in
the air to the extent that combustion cannot be sustained, breathing also
cannot be sustained. Exposure of a person to high concentrations of CO2 or
PKP will cause suffocation.
For this reason, if you must fight an
electrical fire in an enclosed space, wear an oxygen producing respirator
and have assistants standing by to render assistance.
b. First Aid for Electric Shock.
A fatal shock can occur from 0.1
amperes of current. However, voltages as low as 30 volts have been recorded
as causing fatality. It is current which kills, not voltage.
A person who has stopped breathing is not necessarily dead, but is in
immediate danger. Life is dependent upon oxygen, which is breathed into the
lungs and then carried by the blood to every body cell. Since body cells
cannot store oxygen, and since the blood can hold only a limited amount
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