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Electrical Safety > LSafety > Flashcards

LSafety Flashcards

1
Q

What are the 6 major causes of accidents?

A 
Pre-occupation
Ignorance
Over familiarity
Laziness & fatigue 
Physical hazards
Horseplay
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2
Q

What are the 3 main steps to eliminate accidents?

A

Know the hazard, know the precaution
Maintain safety discipline
Get in habit of noticing potential dangers

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3
Q

What are the 3 main causes of electric shock?

A 
Equipment failure (indirect contact)
Human failure (direct contact)
Equipment & human error
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4
Q

List 4 currents and their effect on the body.

A

1mA - Involuntary reaction
10mA - Prevent hold release
20mA - Physical damage
30mA - Can kill

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5
Q

Name 4 effects of electrical shock.

A

Immediate death or unconsciousness
Paralysis of respiration muscles causing asphyxia
Electric burns
Physiological shock

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6
Q

What are the 6 steps of electric shock procedure?

A 
Raise the alarm
Isolate person from supply 
Stand on an insulator and, using an insulator, try to push/pull casualty clear of contact
Check for response 
Keep shouting until help arrives
Carry out first aid, if qualified
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7
Q

What voltage on board is considered to be safe?

A

24 V D.C

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8
Q

Give 5 reasons for using the lock off/tag out procedure.

A

Allow maintenance to proceed without hazard to maintainers.
Isolate equipment that is defective and its operation may be dangerous.
Prevention of the selection of a mode of equipment operation which may be unavailable or defective.
Where supplies are provided but equipment has not been fitted.
Where equipment has been removed.

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9
Q

What is LOTO?

A

It is a safe system of work which facilitates the isolation of ships equipment and systems rendering them safe to work on.

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10
Q

Name 6 scenarios where you would require a permit to work as well as carrying out LOTO.

A 
Shore supply
Fueling
Turning shafts
Divers down
Confined spaces
Working aloft
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11
Q

What are the 4 sections of LOTO?

A

The LOTO index sheet
The LOTO safety certificate
LOTO label
LOTO display board

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12
Q

What are the 2 parts of long term LOTO?

A

Long term LOTO index

Long term LOTO safety certificate

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13
Q

What are the 8 LOTO procedure steps?

A

Obtain permission from senior rate to carry out isolations
Identify all points of isolation
Inform users and anyone who may be effected by removal of supplies
Fill out entry in index sheet and collect next sequential serial number
Senior rate and person requiring LOTO to complete relevant sections of LOTO safety certificate and sign
Complete LOTO label parts A, B and C
Remove fuses and attach part A to empty fuse holder
Place part B of LOTO label on LOTO board and place part C of LOTO label, with fuses, in box provided

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14
Q

What are the 5 steps for the procedure of removing fuses?

A

Place finger firmly in the center of the fuse holder
With free hand, unscrew fuse holder using fuse key
When fully unscrewed, firmly hold fuse holder, turn the head away from fuse box and remove fuse holder
Remove fuse from fuse holder and keep safe. Replace empty fuse holder to maintain the dead front of the fuse panel
Repeat for the second and third fuse way

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15
Q

Whats the procedure before replacing a fuse?

A

The person who conducted LOTO should be the person who tags the equipment/system back in.
If not available, the authorizing individual can brief another competent person to restore supplies.
Obtain permission to restore supplies.
Ensure the equipment is switched off.
Obtain the fuses for the correct circuit from the LOTO box and remove part C of the label and keep safe.
Remove part A of the label and hand to the authorizing individual.
Replace the fuses.
Remove part B of the LOTO label and hand to the authorizing individual.

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16
Q

What is the procedure to physically replace a fuse?

A

Remove empty fuse holder from the fuse way.
Using approved equipment, test for voltage across empty fuse way to ensure it is dead.
If zero volts is detected, replace the fuse.
Repeat for fuse way 2 and 3.
Ensure correctly rated fuse is used.
Avert eyes, locate fuse carrier onto bus bars.
Tighten with fuse key while holding the fuse carrier firmly in place.
Person completing LOTO should have parts A, B and C ready for inspection by senior rate.
Complete section 2A of the LOTO safety certificate.

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17
Q

How would you prove that a system is dead before working on it?

A

Using approved test equipment, test for voltage across empty fuse way to ensure fuse way is dead. This proves that the equipment isolating switch/breaker is still open.

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18
Q

What are the dangerous components and their hazards on ship?

A

Tantalum capacitors - an electrical component that stores electricity and can explode under certain conditions. They will spray sulphuric acid. Found in AVR’s. Necessary to wear face protection.

Selenium rectifiers - electrical component that converts AC to DC. They release toxic dust when they burn out during operation. Must not be inhaled or ingested.

Lotoxane / Penetone - degreaser for electrical components. Can be very toxic. 12 month shelf life, flash point 53 degrees c.

Radioactive valves - class one theta sign, class two trefoil symbol and says class two, hazard terfoil symbol and work caution in black.

19
Q

What are the precautions for using Penetone TPC?

A

Keep away from naked flames.
Supply and exhaust fans to be running.
Never spray directly onto electrical equipment.
Always wear gloves.

20
Q

What PPE should be worn in the galley?

A

DMS boots, overalls or 4s with sleeves down, chefs hat.

21
Q

What is the biggest hazard in the galley?

A

Deep fat fryer due to high temperatures used to heat oil.

22
Q

How do we control supplies to the galley?

A

Via isolating switches which are painted red. They are located just outside the galley.

23
Q

At what voltage is work on live electrical equipment never to be carried out?

A

1000 V AC

1500 V DC

24
Q

What 12 precautions must be taken while working on live electrical equipment?

A

Do not take risks.
Wear rubber gloves if practical.
Use insulated tools.
Stand on rubber insulated mats, avoid leaning on equipment.
Wear insulated footwear.
Be aware of voltages that can be or are present.
Do not rely on interlocks or other safety devices.
Unless essential, do not render interlocks or safety devises inoperable.
Do not work alone. Make sure your assistant knows the electric shock procedure and where the power supply is.
Take care that tools do not cause short circuits.
Work with one hand if possible, keep other hand in pocket.
Check all items of portable equipment has been tested and has in date label.

25
Q

When is live equipment worked on?

A

Only when no alternative is available and when accompanied by an ME senior rate.

26
Q

What must be done before working on dead equipment?

A

Isolate and carry out correct tag out procedure.
Prove that it is dead by using a GPTME to test for voltage between phases and phase and earth.
Discharge any capacitors in the circuit using GPTME.
If required, fit shorting straps to prevent capacitors from recharging.

27
Q

What are the three types of changeover switches?

A

Normal/alternative
Normal/emergency
Normal/alternative/emergency

28
Q

When are changeover switches never used?

A

When the equipment they feed is running.

29
Q

Why do we have changeover switches?

A

Essential equipment on board must have more than one supply. Changeover switches are used to switch between normal, alternative and emergency supplies.

30
Q

What is high voltage defined as?

A

Voltages exceeding 1000 V AC or 1500 V DC between any two circuit conductors. Voltages exceeding 600 V AC or 900 V DC between conductor and earth.

31
Q

What is HV live?

A

Ship is either generating HV, capable of generating HV or connected to external HV shore supply.

32
Q

What is HV dead?

A

Ship is no longer capable of generating, distributing or receiving HV All sources of HV are disconnected and isolated with circuit main earths applied.

33
Q

What is HV safe?

A

Particular area is safe to enter with all forms of HV power sources disconnected and HV decay periods have elapsed.

34
Q

What documents are used with control of HV systems?

A

Permit to work
Sanction for test
Limitation of access
Switching schedule

35
Q

What personnel are involved in HV system control?

A

Authorising engineer
Authorised person
Authorised person in control
Competent person

36
Q

What is a CP?

A

Competent person - a person who has sufficient technical knowledge or experience to enable the person to avoid danger from electrical hazards.

37
Q

What is arc flash?

A

The uncontrolled conduction of electrical current from phase to ground, phase to neutral, and/or phase to phase.

38
Q

What is the most likely occurrence of arc flash?

A

When breakers are racked in and out and when making or breaking the electrical connections.

39
Q

What are the forms of energy released by an arc flash?

A 
Heat
Plasma
Light
Pressure wave
Shrapnel
Sound
Smoke
40
Q

What are the three types of radioactive valves?

A

Class one
Class two
Hazard

41
Q

What are examples of human failure?

A

Shoddy work
Over familiarity
Working in damp surroundings
Failure to test portable equipment

42
Q

What is an example of equipment failure?

A

Insulation on a kettle failing, causing it to become live.

43
Q

What is an example of equipment and human error?

A

Failing to repair damaged leads when doing maintenance.

Using unapproved test equipment.

Electrical Safety (1 decks)

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