Electric Shock Safety and Procedures

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Questions and Answers

What unit is the measure of electric shock intensity?

Current (Amperes)

What level of current will a person be unable to let go?

10 Milliamps

What level of current can be fatal if felt for more than 1 second?

100 Milliamps

PPE is required when working with what voltage?

30 Volts and above Signup and view all the answers

What are the symptoms of electric shock?

Pale, bluish color, weak pulse/breathing, body stiffness Signup and view all the answers

If someone experiences electric shock, what action should be taken for loss of breathing?

CPR Signup and view all the answers

What are the first two steps when someone is being electrocuted?

Shut off power (or remove victim with dry, non-conductive material); Administer first aid Signup and view all the answers

What is a flash protection boundary?

Unobstructed standoff distance from an energized circuit in which unprotected skin could receive a second degree burn from an arc flash Signup and view all the answers

What is the purpose of equipment grounding?

Provide low resistance path away from human in event of electrical or mechanical failure Signup and view all the answers

What is an EMI Filter used for?

To reduce the amount of interference to shipboard electrical and electronic systems Signup and view all the answers

What are TVSS systems?

Transient Voltage Surge Suppression Systems Signup and view all the answers

What are Arc Fault Detection Systems?

Installed on electrical switchboards and load centers, they detect an Arc Flash and send an open signal to the switchboard to minimize damage. Signup and view all the answers

Work on energized systems above this voltage is prohibited unless approved by NAVSEA.

1000 Volts Signup and view all the answers

When may interlocks be 'cheated'?

Only when using an approved procedure (3M) Signup and view all the answers

Whose approval is required for work on energized electrical equipment over 30 volts?

Commanding Officer Signup and view all the answers

What are some safety precautions when working on energized equipment?

All metal removed from person, rubber gloves, work with one hand only, insulate deck, dry clothes, CPR qualified person on scene, safety observers with non-conductive tools and safety line (over 300 volts) Signup and view all the answers

What are STW Checks?

Safe-to-Work checks Signup and view all the answers

What safety checks must be completed during STW checks?

Verify Danger Tags, WAFs, TORs, MRCs, and voltages Signup and view all the answers

When do STW checks not need to be completed?

When working with under 30 Volts Signup and view all the answers

What is 'deranged equipment' now called?

Damaged equipment Signup and view all the answers

For repair activity work conducted shipboard not IAW NSTM Chapter 300, a ___ between shipyards/repair activities and Ship's Force must be documented.

Memorandum of agreement Signup and view all the answers

For naval applications, voltages greater than or equal to ___ are considered high voltage.

1000 volts Signup and view all the answers

The resistance of a human body is about ___

500 ohms Signup and view all the answers

When the skin is damp, the resistance of a human body is about ___

300 ohms Signup and view all the answers

A situation where electrical current passes through air gaps between ungrounded conductors or between conductors and grounded components is called?

Arc flash Signup and view all the answers

Another product of an arc flash is the incident energy, which is ___

Radiant energy Signup and view all the answers

Occurs when the severity of an arc or short circuit current causes destructive heating and explosive vaporization of both the surrounding air and the metal in the current path?

Arc blast Signup and view all the answers

The unobstructed distance from exposed energized circuits within which unprotected skin could receive a second degree burn if an arc flash were to occur is known as?

FPB Signup and view all the answers

Flash Protection Boundaries is abbreviated as?

FPB Signup and view all the answers

The FPB distance aboard a ship for 450-volt circuits is ___

4 feet Signup and view all the answers

The FPB distance aboard a ship for 4160-volt circuits is ___

11 feet Signup and view all the answers

The FPB distance aboard a ship for 13.8K volt circuits is ___

13 feet Signup and view all the answers

An FPB of 4 feet is applicable to circuits with rated voltages between ___

30-1000 volts Signup and view all the answers

An FPB of 11 feet is applicable to circuits with rated voltages between ___

1000 to 5000 volts Signup and view all the answers

An FPB of 13 feet is applicable for voltages ___

Greater than 5000 Signup and view all the answers

Study Notes

Electric Shock and Current

Electric shock intensity is measured in Amperes (current).
10 milliamps is the current level at which a person cannot release their grip.
A current of 100 milliamps can be fatal if sustained for more than one second.

Personal Protective Equipment (PPE)

PPE is mandatory when working with voltages of 30 volts and above.

Symptoms and Emergency Actions

Symptoms of electric shock include pale or bluish skin, weak pulse or breathing, and body stiffness.
Perform CPR if a person loses breathing due to electric shock.
First two steps during an electrocution incident: shut off power (or remove the victim using dry, non-conductive materials) and administer first aid.

Safety and Protection Measures

Flash protection boundary (FPB) is defined as the distance from an energized circuit that could cause a second-degree burn from an arc flash.
Equipment grounding ensures a low-resistance path to reduce dangers from electrical failures.

Electrical Systems and Protection Devices

EMI Filters minimize interference in shipboard electrical and electronic systems.
Transient Voltage Surge Suppression (TVSS) systems absorb and clamp voltage spikes on the main AC bus.
Arc Fault Detection Systems are installed on switchboards to detect arc flashes and minimize damage.

Voltage Regulations and Approvals

Work on energized systems is prohibited above 1000 volts unless approved by NAVSEA.
Commands for work on energized electrical equipment over 30 volts require Commanding Officer approval.

Safe Practices in Energized Conditions

Safety precautions include removing all metal, wearing rubber gloves, using one hand while working, and ensuring someone CPR qualified is present.
Safe-to-Work (STW) checks are necessary after prolonged inactivity or changes in boundaries, including verifying danger tags, work authorization forms (WAFs), and voltage levels.
STW checks are unnecessary when working on systems under 30 volts.

Equipment and Voltage Classifications

"Deranged equipment" is now referred to as damaged equipment.
For naval applications, voltages equal to or greater than 1000 volts are categorized as high voltage.

Human Body Resistance

The average resistance of a human body is around 500 ohms, which decreases to 300 ohms when the skin is damp.

Arc Phenomena

An arc flash occurs when current passes through air gaps between ungrounded conductors or between conductors and ground.
Incident energy from an arc flash is classified as radiant energy.
An arc blast results from severe heating due to high current, leading to explosive vaporization of air and surrounding metal.

Flash Protection Boundary (FPB) Details

FPB defines the distance where unprotected skin could suffer burns from an arc flash.
FPB ranges for energized circuits aboard ships:
- 4 feet for circuits rated between 30-1000 volts.
- 11 feet for circuits rated between 1000-5000 volts.
- 13 feet for voltages exceeding 5000 volts.

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Description

This quiz covers essential knowledge on electric shock intensity, symptoms, and emergency responses. It also highlights the importance of Personal Protective Equipment (PPE) and safety measures when handling electricity. Prepare to learn and assess your understanding of electrical safety protocols.