Junior Lineman / Energy Assistant — ITI Electrical Quick Book · Chapter 1

Electrical Safety, First Aid, Tools and Electricity Rules

What to remember

Electricity kills by current, not voltage alone. Even about 30 mA through the chest can stop breathing, and about 100 mA or more can cause ventricular fibrillation. 50 Hz mains is especially dangerous.
Never use water on an electrical fire. Switch off the supply first. Use a CO₂ or dry chemical powder extinguisher.
Treat every line as live until it is tested dead, isolated, earthed and shown with a permit. The Electricity Act 2003 and the safety regulations of the Central Electricity Authority set the legal rules.

Electric shock and its effects

The seriousness of a shock depends on four things: the amount of current, the path through the body (hand to hand or hand to foot across the heart is worst), the time of contact and the frequency of supply. Body resistance falls sharply when the skin is wet, cut or sweaty, so the same voltage is far more dangerous in wet conditions.

Current (approximate, 50 Hz)	Effect
About 1 mA	Just felt (threshold of perception)
About 10 mA	Muscles may not let go ("let-go" limit); painful
About 30 mA	Breathing becomes difficult
100 mA and above	Ventricular fibrillation; may be fatal
Several amperes	Severe burns; heart stops

Other hazards: burns from contact or arc, arc flash and blast, falls from poles after a shock, fire from overloaded or loose connections.

Ohm's law shows why: I = V / R. At 230 V with a body resistance of 1000 Ω, I = 0.23 A = 230 mA. This is far above the fatal level.

Safe working practice

The five basic safety steps before work on a line or equipment:

1. Isolate the supply from all sides (open the switch or remove the fuse).
2. Secure against reconnection (lock and tag; keep the key with you).
3. Verify that the circuit is dead using an approved voltage detector, after checking the detector on a known live source.
4. Earth and short-circuit the conductors on both sides of the work place.
5. Guard or cover nearby live parts and display danger boards.

Other good practice:

Work only with a permit to work (PTW) given by the competent person, and return it when the job ends.
Lock-out / tag-out: the person doing the work puts his own lock and tag; only he removes them.
Use insulated tools, rubber gloves, rubber mats, safety helmets, safety shoes and safety belts. Check the gloves for holes before use.
Never work alone on high-voltage jobs. Keep a second person trained in first aid.
Do not wear metal rings or watches near live parts.
Discharge capacitors and cables before touching them. Treat a transformer or cable as live until earthed.
Do not climb a pole until the line is proved dead and earthed. Use a safety belt and a proper pole climbing device.
Keep a first-aid box, a fire extinguisher and the emergency numbers at hand.
Use the earthing system for all metal bodies. Earthing (IS 3043 gives the code) keeps the exposed parts at ground potential; a good earth has a low resistance.
Colour code (current Indian practice): red, yellow and blue for the three phases, black for neutral, green or green-yellow for earth.

Protective devices

Device	Purpose
Fuse	Melts under over-current; protects wiring
MCB	Resets after tripping; protects against overload and short circuit
ELCB / RCCB	Detects earth leakage current; for personal protection it is set at 30 mA or less
Earthing	Gives fault current a low-resistance path to ground
Lightning arrester	Diverts surge to earth
Insulation	Keeps live parts apart from people

Fire and fire fighting

Fire needs fuel, heat and oxygen (the fire triangle). Classes of fire:

A: solids such as wood, paper, cloth.
B: flammable liquids such as oil and petrol.
C: gases.
D: metals.
Electrical fires: put out the supply first, then use CO₂ or dry chemical powder (DCP). Never use water or foam on live equipment.
Remember the sequence for an extinguisher: pull the pin, aim at the base of the fire, squeeze the handle and sweep from side to side.
Sand buckets are used on oil fires. A fire blanket smothers small fires.

First aid for electric shock and burns

1. Do not touch the victim while he is still in contact with the live part.
2. Switch off the supply at once. If this is not possible, push or pull the victim away with a dry insulating material such as dry wood, a rubber mat or a dry rope. Stand on a dry insulating surface.
3. Check response, breathing and pulse. Call for medical help.
4. If there is no breathing, begin CPR (cardiopulmonary resuscitation). The usual ratio is 30 chest compressions followed by 2 rescue breaths, at a rate of about 100 to 120 compressions per minute. Continue until help arrives.
5. If the victim is breathing but unconscious, place him in the recovery position.
6. Cool burns with clean running water for several minutes. Cover with a clean dry dressing. Do not apply ointment, oil or ice, and do not burst blisters.
7. Control bleeding by firm pressure with a clean cloth and raise the limb.
8. For a fall from a height, do not move the victim unless there is danger, because of possible spine injury.

Hand tools and instruments of an electrician

Combination pliers for gripping and cutting; long-nose pliers for small work; side cutters for cutting wires.
Screwdrivers: flat and Philips (cross) types; use insulated handles. A neon tester (phase tester) is a screwdriver with a lamp for checking live wires.
Wire stripper, crimping tool (for lugs and terminals), soldering iron, hacksaw, hammer, chisel, drill machine.
Spanners and wrenches: open-ended, ring and adjustable.
Multimeter: voltage, current and resistance. Clamp (tong) tester: current without breaking the circuit.
Megger (insulation resistance tester): measures insulation resistance, normally with 500 V DC for low-voltage wiring. Disconnect the supply before testing.
Earth tester: measures earth resistance.
Lineman tools: climbing belt and pole climbing device, rope, pulley, insulated sticks, tension tools, and earthing rods.

Electricity Act and rules (overview)

The Electricity Act, 2003 is the main law for generation, transmission, distribution, trading and use of electricity. It also deals with electricity theft and unsafe practices.
The Central Electricity Authority (CEA) frames technical standards and safety regulations. The older Indian Electricity Rules, 1956 gave the classic voltage classes; the CEA safety regulations are the current rules. Check the latest official text for clause details.
Voltage classes (classic IE Rules 1956): low up to 250 V; medium above 250 V to 650 V; high above 650 V up to 33 kV; extra-high above 33 kV.
Licensee and consumer duties: keep lines safe, give notice of an accident, follow the inspection rules, and keep earthing in good order.
Electrical accidents: all serious accidents must be reported to the authority (the electrical inspector) in the prescribed manner.
Only a licensed electrical contractor and supervisor may undertake installation work as per the licence.
Insulators, clearances above ground and from buildings are fixed by the regulations; read the current table before use.

Worked examples

1. Shock current: 230 V and 1000 Ω body resistance give I = 230 / 1000 = 0.23 A = 230 mA.
2. Dry skin: 230 V and 100 000 Ω gives I = 2.3 mA, only a mild shock.
3. Power and current: a 2 kW heater at 230 V draws I = 2000 / 230 ≈ 8.7 A. A 10 A fuse is a suitable next size up.
4. Insulation test: the megger reads 5 MΩ on a 500 V test. Leakage current = 500 / 5 000 000 = 0.1 mA.
5. Loop heating: I²R: 10 A through 0.5 Ω gives 100 × 0.5 = 50 W of heat.
6. CPR cycle: 30 compressions at 120 per minute take 15 seconds.
7. RCCB: a 30 mA device trips if leakage exceeds 30 mA; it limits the duration of a shock (cutting off within about 30 ms), not the size of the current.

Exam traps

Current, not voltage alone, kills; but a higher voltage drives more current.
Never use water on an electrical fire; CO₂ and DCP are right for live equipment.
The first step in rescue is to switch off the supply, not to touch the victim.
A fuse protects wiring; an RCCB protects people from earth leakage.
CPR ratio is 30:2.
Phase colours are red, yellow, blue; neutral is black; earth is green or green-yellow.
A megger tests insulation; an earth tester tests earth resistance.
A clamp tester reads current without breaking the circuit.
Earthing protects equipment bodies; it does not carry normal load current.
Lock-out and tag-out is removed only by the person who applied it.

One-liners

1. 50 Hz AC is more dangerous than DC of the same value.
2. Safety belt is a must for work on poles.
3. Permit to work is issued by a competent person.
4. CO₂ extinguishers are suitable for electrical fires.
5. A phase tester shows whether a wire is live.
6. A megger tests insulation resistance.
7. A neutral wire is black.
8. RCCB means residual current circuit breaker.
9. Earth wire is green or green-yellow.
10. CPR is 30 compressions to 2 breaths.
11. Fire needs fuel, heat and oxygen.
12. Electricity Act 2003 is the principal law.

Practice questions

Which fire extinguisher is suitable for an electrical fire?
1. Water extinguisher
2. Foam extinguisher
3. Carbon dioxide (CO₂) extinguisher
4. Soda-acid extinguisher
Answer
C. Carbon dioxide (CO₂) extinguisher
CO₂ is non-conducting and leaves no residue; water and foam conduct current.
The first action when you see a person stuck to a live wire is to
1. run for a doctor first
2. pour water on him
3. pull him by the hand
4. switch off the supply
Answer
D. switch off the supply
Break the contact with the supply safely before touching the victim.
What is the ratio of chest compressions to rescue breaths in adult CPR?
1. 5 : 1
2. 30 : 2
3. 15 : 1
4. 10 : 5
Answer
B. 30 : 2
The standard cycle is 30 compressions and 2 breaths.
Which instrument is used to measure insulation resistance?
1. Megger
2. Ohmmeter with 1.5 V cell
3. Wattmeter
4. Clamp meter
Answer
A. Megger
A megger applies a high DC voltage, usually 500 V for LV wiring, to test insulation.
A phase tester (neon tester) is used to
1. measure earth resistance
2. check whether a wire is live
3. measure power
4. measure current
Answer
B. check whether a wire is live
The neon lamp glows when the tip touches the live wire.
Which tool measures current without breaking the circuit?
1. Clamp (tong) tester
2. Earth tester
3. Megger
4. Phase tester
Answer
A. Clamp (tong) tester
The jaw of the clamp meter senses the magnetic field of the current.
The colour of the neutral wire in current Indian wiring practice is
1. red
2. yellow
3. green
4. black
Answer
D. black
Phases are red, yellow and blue; neutral is black.
The earth wire in a modern installation is
1. red
2. grey
3. green or green-yellow
4. blue
Answer
C. green or green-yellow
Green or green-yellow is the standard earth colour.
Which class of fire involves flammable liquids?
1. Class D
2. Class A
3. Class B
4. Class C
Answer
C. Class B
Class A is solids, B liquids, C gases, D metals.
For personal protection against earth leakage an RCCB is normally rated at
1. 5 A
2. 30 mA or less
3. 1 A
4. 300 mA
Answer
B. 30 mA or less
A 30 mA device limits shock current to a non-fatal level.
A permit to work is issued by
1. the helper
2. the contractor's driver
3. any consumer
4. a competent authorised person
Answer
D. a competent authorised person
Only an authorised competent person may issue the permit.
The principal law for the electricity sector in India is the
1. Factories Rules
2. Water Act
3. Telegraph Rules only
4. Electricity Act, 2003
Answer
D. Electricity Act, 2003
The Electricity Act 2003 governs generation to supply.
Extra-high voltage in the classic IE Rules means above
1. 33 kV
2. 11 kV
3. 650 V
4. 132 V
Answer
A. 33 kV
EHV is above 33 kV.
A person with a body resistance of 2000 Ω touches 230 V. The current is
1. 23 mA
2. 11.5 mA
3. 115 mA
4. 1.15 A
Answer
C. 115 mA
I = 230/2000 = 0.115 A.
A 2.3 kW heater is connected to 230 V (unity power factor). The current drawn is
1. 10 A
2. 23 A
3. 5 A
4. 1 A
Answer
A. 10 A
I = P/V = 2300/230 = 10 A.
Insulation tested at 500 V gives 2 MΩ. The leakage current is
1. 2.5 mA
2. 0.25 mA
3. 25 mA
4. 0.025 mA
Answer
B. 0.25 mA
I = 500 / 2,000,000 = 0.00025 A.
A conductor of 0.2 Ω carries 10 A for one hour. The heat produced is
1. 72,000 J
2. 2000 J
3. 7200 J
4. 20 J
Answer
A. 72,000 J
I²Rt = 100 × 0.2 × 3600 = 72,000 J.
If 120 compressions are given each minute, 30 compressions take
1. 5 seconds
2. 30 seconds
3. 60 seconds
4. 15 seconds
Answer
D. 15 seconds
30/120 min = 0.25 min = 15 s.
A motor takes 5 A at 230 V and runs for 4 hours at unity power factor. Energy used is
1. 0.46 kWh
2. 1.15 kWh
3. 4.6 kWh
4. 46 kWh
Answer
C. 4.6 kWh
230 × 5 = 1150 W = 1.15 kW; ×4 = 4.6 kWh.
A fuse of rating 15 A is placed in a circuit of 230 V. The maximum safe power is about
1. 15 kW
2. 3.45 kW
3. 34.5 kW
4. 345 W
Answer
B. 3.45 kW
P = 230 × 15 = 3450 W.
The most dangerous current path through the body is
1. foot to foot only
2. hand to hand or hand to foot across the chest
3. across the fingers of one hand
4. through the ear lobe only
Answer
B. hand to hand or hand to foot across the chest
It passes near the heart and the nervous centres.
Wet skin is more dangerous in a shock because
1. voltage rises
2. frequency falls
3. current is DC
4. body resistance falls sharply
Answer
D. body resistance falls sharply
Lower body resistance allows more current for the same voltage.
Which of the following is an insulating material for rescue from a live wire?
1. Wet cloth
2. Iron rod
3. Dry wood
4. Wet rope
Answer
C. Dry wood
Dry wood is a non-conductor; wet items and metals are not.
The first step in the safe procedure for working on a dead line, after isolating, is to
1. secure it against reconnection
2. start work at once
3. fit new fuses
4. remove the danger board
Answer
A. secure it against reconnection
Isolate, secure, verify dead, earth and short-circuit, cover adjacent live parts.
Before touching a conductor declared dead, a lineman must
1. touch it lightly with the back of the hand
2. rely on the switch position only
3. test it with a voltage detector and then earth it
4. just look at the lamp
Answer
C. test it with a voltage detector and then earth it
Verify dead with an approved detector and then earth.
Which class of fire involves metals such as magnesium?
1. Class C
2. Class B
3. Class A
4. Class D
Answer
D. Class D
Class D covers combustible metals.
For burns from electric shock, the first aid is to
1. apply butter or oil
2. cool with clean running water and cover with clean dry dressing
3. apply ice directly
4. burst the blisters
Answer
B. cool with clean running water and cover with clean dry dressing
Cooling and a clean dressing are the standard first aid.
An unconscious person who is breathing normally should be placed in
1. the recovery position
2. a sitting position
3. a standing position
4. a face-up position with legs hanging
Answer
A. the recovery position
The recovery position keeps the airway clear.
Which tool is used to fix lugs on cable ends?
1. Crimping tool
2. Combination plier
3. Chisel
4. Hacksaw
Answer
A. Crimping tool
Crimping tools press lugs onto the conductor.
Which of the following is a purpose of an earth connection?
1. To reduce the power factor
2. To give fault current a low-resistance path to ground
3. To carry the normal load current
4. To raise the supply voltage
Answer
B. To give fault current a low-resistance path to ground
Earthing keeps metal bodies at ground potential and lets protective devices operate.
A fuse is used to protect against
1. over-current
2. over-frequency
3. low voltage only
4. poor power factor
Answer
A. over-current
A fuse melts under excess current.
Consider: 1. 50 Hz AC can cause muscle lock so that the victim cannot let go. 2. Dry skin has lower resistance than wet skin.
1. 1 only
2. 2 only
3. Both 1 and 2
4. Neither 1 nor 2
Answer
A. 1 only
Wet skin has lower resistance; dry skin is higher.
Consider: 1. Water should not be used on a live electrical fire. 2. A CO₂ extinguisher conducts electricity well.
1. 1 only
2. 2 only
3. Both 1 and 2
4. Neither 1 nor 2
Answer
A. 1 only
CO₂ is a non-conducting extinguishant.
Consider: 1. A megger measures insulation resistance. 2. A clamp meter must be connected in series with the circuit.
1. 1 only
2. 2 only
3. Both 1 and 2
4. Neither 1 nor 2
Answer
A. 1 only
A clamp meter surrounds the conductor and is not put in series.
Consider: 1. Lock-out and tag-out is removed only by the person who applied it. 2. A permit to work can be issued to anybody who asks.
1. 1 only
2. 2 only
3. Both 1 and 2
4. Neither 1 nor 2
Answer
A. 1 only
The permit is issued by a competent person to the person doing work.
Consider: 1. An RCCB protects against earth leakage. 2. A fuse protects against earth leakage at 30 mA.
1. 1 only
2. 2 only
3. Both 1 and 2
4. Neither 1 nor 2
Answer
A. 1 only
A fuse protects against over-current, not small leakage.
Consider: 1. Electricity Act 2003 deals with electricity theft. 2. The Central Electricity Authority frames technical standards and safety regulations.
1. 1 only
2. 2 only
3. Both 1 and 2
4. Neither 1 nor 2
Answer
C. Both 1 and 2
Both statements are correct.
Consider: 1. The earth wire carries normal load current. 2. The neutral wire is black.
1. 1 only
2. 2 only
3. Both 1 and 2
4. Neither 1 nor 2
Answer
B. 2 only
Normal load current flows in phase and neutral, not the earth wire.
Consider: 1. Phase colours are red, yellow and blue. 2. Neutral is coloured red.
1. 1 only
2. 2 only
3. Both 1 and 2
4. Neither 1 nor 2
Answer
A. 1 only
Neutral is black in present practice.
Consider: 1. A body resistance of 1000 Ω with 230 V gives a current of 0.23 A. 2. A 1 mA current is usually fatal.
1. 1 only
2. 2 only
3. Both 1 and 2
4. Neither 1 nor 2
Answer
A. 1 only
1 mA is only just perceptible.
Match the class of fire to its fuel: 1. A 2. B 3. D.
1. Gases; liquids; solids
2. Liquids; solids; metals
3. Metals; solids; liquids
4. Solids; liquids; metals
Answer
D. Solids; liquids; metals
Class A solids, B liquids, D metals.
Match the instrument to its use: 1. Megger 2. Earth tester 3. Phase tester.
1. Earth resistance; insulation resistance; checking live wire
2. Checking live wire; earth resistance; insulation resistance
3. Insulation resistance; earth resistance; checking live wire
4. Insulation resistance; checking live wire; earth resistance
Answer
C. Insulation resistance; earth resistance; checking live wire
Megger tests insulation, earth tester tests earth resistance, phase tester indicates live wire.
Match the voltage class to the range: 1. Low 2. Medium 3. High.
1. Up to 250 V; 650 V–33 kV; 250–650 V
2. Up to 650 V; 650 V–33 kV; above 33 kV
3. 250–650 V; up to 250 V; above 33 kV
4. Up to 250 V; 250–650 V; 650 V–33 kV
Answer
D. Up to 250 V; 250–650 V; 650 V–33 kV
Classic classes: low up to 250 V, medium 250–650 V, high 650 V–33 kV.
Which personal protective item is a must when climbing an electric pole?
1. Plastic slippers
2. Woollen cap
3. Sunglasses
4. Safety belt
Answer
D. Safety belt
A belt prevents a fall after a shock or slip.

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1.The charge of two H + ions is ________.
2.The charge flowing through a circuit in 10 minutes is 300 C. Find the current drawn by the circuit.
3.The correct relation between charge(Q) following through a conductor, time(t) for which the charge follows and the current (I) following through the conductor is:
4.The formula of current I = _______ /time (t).
5.The generation of heat in a conductor due to electric current is known as:
6.The effective resistance of the parallel combination of two resistors is always _______
7.The electric dipole moment per unit volume is called ___________.
8.The electric current flowing through a metallic wire is directly proportional to the potential difference V across its ends, provided its _____ remains the same.
9.The electric ______ between two points in an electric circuit carrying some current is the work done to move a unit charge from one point to the other.
10.The electric power consumed by a resistor of resistance R, carrying current I, is _______

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