NSTM 300 Flashcards

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Questions and Answers

Which of the following are sources of information contained in NSTM 300? (Select all that apply)

Maintenance of electrical equipment (correct)

Electrical Safety Precautions (correct)

Reconditioning electrical equipment after contamination (correct)

Electrical Insulation (correct)

What are the contents of the 9 Appendix? (Select all that apply)

Electrical/Electronic Workbenches (correct)

Certification Procedure for Providing Motors with a Sealed Insulation system (correct)

Safety Supplement (correct)

Electrical Insulating Materials (correct)

TYCOMs and commands shall not issue any guidance contradictory to the NSTM 300 without approval from ________.

NAVSEA

What is an Arc Flash?

A situation where electrical current passes through air gaps between ungrounded conductors or between conductors and grounded components Signup and view all the answers

What are possible causes of Arc Flash? (Select all that apply)

Insulation breakdown Signup and view all the answers

What occurs during an Arc Blast?

Destructive heating and explosive vaporization of both the surrounding air and the metal in the current path Signup and view all the answers

Molten metal and gas is expelled away from the arc at speeds exceeding __________ mph.

700 Signup and view all the answers

The sound of the blast can exceed ________ dB.

160 Signup and view all the answers

What is the Flash Protection Boundary?

The unobstructed distance from exposed energized circuits within which unprotected skin could receive a second degree burn. Signup and view all the answers

Arc flash protection is required for routine operations.

False Signup and view all the answers

Match the following Flash Protection Boundary distances with their corresponding voltages:

-30 volts to 1000 volts = 4 feet 1000 volts to 5000 volts = 11 feet Greater than 5000 volts = 13 feet Signup and view all the answers

Commanding Officer's permission is not required when performing IVV or safe-to-work voltage checks.

True Signup and view all the answers

What are the IVV Risk Categories? (Select all that apply)

High risk Signup and view all the answers

Low risk is defined as less than or equal to ________V.

30 Signup and view all the answers

Medium risk is classified as greater than ________V and less than 1000V.

30 Signup and view all the answers

High risk includes equipment rated at ________V or greater.

1000 Signup and view all the answers

What is required whenever equipment or circuits have been verified de-energized?

Safe to work (STW) Signup and view all the answers

Study Notes

NSTM 300 Overview

NSTM 300 includes critical topics such as sources of information, electrical safety precautions, electrical insulation, maintenance, and reconditioning of contaminated electrical equipment.

Appendices

Contains 9 appendices covering essential topics:
- A: Electrical insulating materials
- B: Certification procedures for sealed insulation systems in motors
- C: Refurbishment certification for specific motor-generator sets
- D: Banding armatures with resin-treated fibrous-glass
- E: Trickle method for shipboard motor repair
- F: QA inspection procedures for insulating varnishes on Navy equipment
- G: Safety supplement
- H: Electrical/electronic workbench guidelines
- I: Personal protective equipment (PPE) and safety equipment details

Compliance and Approval

Commands and TYCOMs cannot issue contradictory guidance to NSTM 300 without NAVSEA approval.

Arc Flash Definition

An arc flash occurs when electrical current jumps through the air between ungrounded conductors or between conductors and grounded components.

Causes of Arc Flash

Insulation breakdown
Inadequate separation between workers and energized parts
Use of uninsulated tools
Handling conductive objects near exposed energized conductors

Arc Blast Definition

An arc blast results from destructive heating and explosive vaporization caused by arc or short-circuit currents.

Arc Flash Hazards

Molten metal and gas from arcs can be expelled at speeds over 700 mph, posing serious risks, including penetration injuries.
Blast sound levels can exceed 160 dB, potentially rupturing eardrums.

Flash Protection Boundary

Defines the safe distance from energized circuits to prevent second-degree burns from arc flashes.
Flash protection distances vary by voltage:
- 30V to 1000V → 4 feet
- 1000V to 5000V → 11 feet
- Over 5000V → 13 feet
For maintenance, electrical safety distances and flash protection boundaries are the same.

Permission for IVV

Commanding Officer's permission is not needed for Independent Verification and Validation (IVV) or safe-to-work voltage checks.

Risk Categories

IVV risk categories include low, medium, and high risks, based on voltage levels and equipment requirements.
Low risk: ≤ 30V and >30V to <1000V
Medium risk: >30V to <1000V
High risk: Rated 1000V or greater, or requiring over 12 cal/cm² PPE for de-energization verification.

Safe to Work (STW)

STW protocols are required for equipment verified as de-energized, especially if the isolation status is questionable.

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Description

Test your knowledge on NSTM 300 topics with these flashcards. This quiz covers crucial definitions and information related to electrical safety precautions and the maintenance of electrical equipment. Perfect for those involved in electrical engineering and maintenance in maritime contexts.