TB Electrical Hazards Continued. Flashcards
Overhead Transformers - Pole-mounted transformers are the most ___ distribution transformer.
common
Overhead Transformers -
They are installed on the 4.8kv circuits to step the voltage down to ___ volts for most residential consumers.
120/240
Transformers for subsurface electrical are mounted above ground on concrete bases called ____.
pad-mounted transformers
Pad-mounted transformers :
These large boxes are connected to ____ circuits and are located in parking lots of small and medium size businesses or in the front yard of some residences.
4.8kv
The conductors are materials that allow an electric current to flow through them ___.
easily.
Insulators are appliances which will ___ the flow of electricity and provides support to the conductor. They are most commonly made of glass or porcelain.
prevent
The most effective methods of identifying different voltages are:
1. ___ signs on the cross arms.
High voltage
The most effective methods of identifying different voltages are:
2. The size and shape of ____; remember, the ___ at the top of poles will appear smaller than they really are.
insulators
The most effective methods of identifying different voltages are:
3. The distance between ___; the higher the voltage, the greater the distance between _____.
conductors
Common Electrical Distribution Lines:
Primary wires = up to ____ volts of electricity
21,000
Common Electrical Distribution Lines:
Secondary wires = up to ____ volts of electricity
240
Common Electrical Distribution Lines:
Transformer = reduces ____ voltage to secondary voltage
Primary
Common Electrical Distribution Lines:
Electric Service = to house up to ___ volts of electricity
240
Common Electrical Distribution Lines:
Lowest lines =
Phone and Cable service
___ of an amp of electricity going through the body for just ___ seconds is enough to cause death.
1/10 / two
The amount of internal current a person can withstand and still be able to control the muscles of the arm and hand can be less than _____.
10 milliamps (mA).
Currents above ____ can paralyze or “freeze” muscles.
10 mA
People have stopped breathing when shocked with currents from voltages as low as ___ .
49 volts
Usually, it takes about ___ of current to cause respiratory paralysis.
30 mA
Currents greater than ___ may cause ventricular fibrillation (very rapid, ineffective heartbeat).
75 mA
Heart paralysis occurs at ____, which means the heart does not pump at all. Tissue is burned with currents greater than 5 amps.
4 amps
At ___ volts, the current through the body may be as great as 4 amps, causing damage to internal organs such as the heart.
600
Dry skin may have a resistance of ___ ohms or more. Wet skin may have a resistance of only 1,000 ohms.
100,000
The cutting of wires by firefighters must be confined to ____ wires.
low-voltage
