Maharashtra SSC Electrical Technology Pre-Voc/NSQF cheat sheet

Ohm's law: V = I × R; power P = V × I = I²R = V²/R. In a series circuit current is common, in a parallel circuit voltage is common.

Conductors obey V = IR linearly; the resistance of a metallic conductor rises with temperature (positive temperature coefficient), while carbon and electrolytes show a negative coefficient.

Kirchhoff's laws: the algebraic sum of currents at a node is zero (KCL); the algebraic sum of emfs and drops around a closed loop is zero (KVL).

AC quantities: RMS value = peak/√2 = 0.707 × peak; average value of a sine wave = 0.637 × peak; form factor = 1.11; peak factor = 1.414.

Frequency f = 1/T; for a 50 Hz Indian supply the period is 20 ms. Inductive reactance XL = 2πfL; capacitive reactance XC = 1/(2πfC).

Three-phase relations: line voltage = √3 × phase voltage in star; line current = √3 × phase current in delta; power = √3 × VL × IL × cos φ.

First aid for electric shock: isolate the supply first, never touch the victim with bare hands, then assess breathing and call for medical help; use the recovery position if unconscious but breathing.

Fire classes: Class A solid, B liquid, C gas, D metal; CO2 extinguishers are preferred for live electrical fires because the agent is non-conducting and leaves no residue.

Earth-leakage protection: an ELCB/RCCB rated 30 mA trips within milliseconds and protects people; MCBs protect wiring against overload and short circuit but not against small leakage currents.

Copper: resistivity about 1.72 × 10⁻⁸ Ω·m, excellent conductivity, used for house wiring and windings; annealed copper is softer and more ductile than hard-drawn.

Aluminium: resistivity about 2.8 × 10⁻⁸ Ω·m, about 60% of copper's conductivity by volume but lighter, so it is used for overhead transmission conductors such as ACSR.

Insulating classes by temperature: Class Y 90 °C, A 105 °C, E 120 °C, B 130 °C, F 155 °C, H 180 °C, C above 180 °C.

Dielectric strength is the maximum voltage per unit thickness an insulator withstands without breakdown; measured in kV/mm and falls with moisture and heat.

Magnetic materials: soft iron and silicon steel have high permeability and low hysteresis loss (cores); hard steel and alnico retain magnetism (permanent magnets).

Eddy-current loss is reduced by laminating cores; hysteresis loss is reduced by using silicon steel, which narrows the B-H loop.

PVC is used for general wiring insulation up to about 70 °C; XLPE withstands higher temperatures and is used for power cables; rubber is used for flexible cords.

Soldering materials: tin-lead 60/40 melts near 190 °C; lead-free solder melts higher; flux removes oxide and rosin flux is preferred for electrical joints.

Ammeter is connected in series and has very low resistance; voltmeter is connected in parallel and has very high resistance; a meter with the wrong connection can short the supply.

An ammeter shunt extends range: Rshunt = Rm / (n − 1), where n is the multiplying factor. A series multiplier for a voltmeter: Rmult = Rm(n − 1).

A megger (insulation resistance tester) applies a high DC voltage and reads in megohms; a healthy 230 V domestic installation should read at least 1 MΩ to earth.

A multimeter in continuity mode uses its internal battery and buzzer; the circuit must be dead before testing resistance or continuity.

A clamp meter measures current by the magnetic field around a conductor and needs no breaking of the circuit; it reads only one conductor at a time.

Wattmeter has a current coil (in series) and a pressure/voltage coil (in parallel); incorrect polarity of the voltage coil makes the pointer deflect backwards.

An energy meter (kWh meter) is calibrated by counting revolutions; energy = (revolutions × 3600) / (meter constant in rev/kWh) in joules when time is in seconds.

Hand tools: a wire stripper sizes the conductor diameter; a crimping tool makes permanent lugs; a hacksaw blade of 18 TPI suits conduit, 24 TPI suits thin sheet.

A digital multimeter's input impedance is typically 10 MΩ, so it reads nearly true voltage; an analog meter with low ohms-per-volt loads the circuit and reads low.

Cleat wiring uses porcelain cleats and is cheap but temporary; casing-and-capping is surface protection; concealed conduit is required in modern construction because wiring is hidden and protected.

Conduit fill: the total cross-section of conductors should not exceed about 40% of the conduit internal area, so conductors can be drawn without damage.

A batten holder, ceiling rose, and pendant use three-core flexible cable; the earth wire must be connected even if the holder is of insulated body.

Loop-in (joint box) system is preferred over the old joint-box system because it keeps joints accessible at ceiling roses and switches rather than buried in walls.

Two-way switching needs three-core cable between the two switches (common, L1, L2); a staircase light controlled from two points uses two two-way switches.

A one-way switch has two terminals; an intermediate switch has four terminals and is used for control from three or more points.

Domestic load estimation: lighting circuits are wired in 1.5 mm² cable protected at 6 A; power circuits in 2.5 mm² protected at 16 A; a 4 mm² cable suits 20–25 A.

Wire colour convention (Indian practice): phase red/yellow/blue, neutral black, earth green; older installations may use red phase, black neutral, green earth throughout.

Insulation resistance is measured between conductors and between each conductor and earth with all switches on and loads disconnected; the minimum acceptable value is 1 MΩ.

A socket outlet is rated 6 A or 16 A; the 16 A socket is used for heavy appliances and is wired on a separate circuit with its own MCB.

A ceiling rose has terminals for phase, neutral and earth; the pendant flex must be supported by the rose, not by the terminals.

MCB ratings are chosen one step above the circuit design current; an MCB of type B trips at 3–5 times rated current, type C at 5–10 times.

A distribution board should have a separate earth bar, neutral bar and phase busbar; the main switch must disconnect phase and neutral simultaneously in a two-pole device.

Earthing: plate or pipe earth electrode is buried at least 2.5–3 m deep; earth resistance should be below 1 Ω for a substation and below 5–8 Ω for domestic installations.

A fan regulator in series with the fan reduces voltage; electronic (triac) regulators are more efficient than resistive wire-wound regulators.

A bell push is a momentary switch; the bell circuit uses a step-down transformer or a battery so that low voltage reaches the push button.

When mounting a switchboard, the switch is placed about 1.2 m above floor level and the socket about 0.3 m above the floor, with phase on the right-hand terminal.

An electric iron uses a nichrome element and a bimetallic thermostat; the iron not heating usually means an open element or a faulty thermostat contact, checked with a continuity tester.

A mixer-grinder's universal (series) motor has field and armature in series; sparking at the brushes indicates worn brushes, a dirty commutator, or a shorted armature.

An immersion rod or geyser element is checked by measuring resistance across its terminals; a reading of infinity means the element is open, and a low reading to the body means leakage to earth.

An electric fan with a capacitor-run motor that hums but does not start usually has a failed capacitor; a shorted capacitor can blow the fuse.

A refrigerator compressor is a sealed unit; the most common electrical faults are a burnt PTC starter, an open overload protector, and a faulty thermostat, not the compressor itself.

A washing machine's motor may be a capacitor-start induction motor; a blown fuse, faulty lid switch, or open timer contact stops the cycle before the motor runs.

Microwave ovens store lethal charge in the high-voltage capacitor even after unplugging; the capacitor must be discharged through a resistor before any servicing.

Heating appliances: a 1000 W iron on 230 V draws about 4.3 A; the element resistance is V²/P ≈ 53 Ω; the plug and flex must be rated above this current.

Transformer EMF equation: E = 4.44 f N Φm; the ratio V1/V2 = N1/N2 = I2/I1 for an ideal transformer.

Transformer losses: copper (I²R) losses vary with load and are found by the short-circuit test; iron (core) losses are constant and found by the open-circuit test.

A transformer works only on AC; it cannot change the frequency, and it does not change the power (apart from losses).

DC motor back EMF: Eb = V − IaRa; torque T ∝ ΦIa; a series motor must never be started without load because its speed rises dangerously.

Induction motor slip s = (Ns − N)/Ns; synchronous speed Ns = 120f/P; a 4-pole motor on 50 Hz has Ns = 1500 rpm.

Star-delta starter reduces starting current to one-third of the direct-on-line value; a direct-on-line starter is used only for small motors.

DC generator EMF: Eg = (PΦNZ)/(60A) where P is poles, Z conductors, N rpm, A parallel paths; the commutator converts armature AC to external DC.

Alternator frequency f = PN/120, where N is rpm and P is the number of poles; a 2-pole alternator at 3000 rpm gives 50 Hz.

Motor protection: a thermal overload relay protects against sustained overload, while a fuse or MCCB protects against short circuit; both are needed.

Lead-acid cell: nominal emf about 2 V per cell; a 12 V battery has six cells in series; fully charged specific gravity of electrolyte is about 1.28 and discharged about 1.15.

During discharge, lead-acid plates convert to lead sulphate; during charging the reactions reverse, water is electrolysed near full charge and must be topped up with distilled water only.

Battery capacity is rated in ampere-hours (Ah) at a stated discharge rate; a 100 Ah battery can deliver 5 A for about 20 hours at the 20-hour rate.

Efficiency: Ah efficiency = (Ah out)/(Ah in); Wh efficiency is always lower because the discharge voltage is lower than the charge voltage.

Li-ion cells have a nominal 3.6–3.7 V per cell and must never be overcharged or deep-discharged; a protection circuit or BMS is mandatory.

A UPS with an inverter converts DC battery energy to AC; the inverter's output waveform is sine or quasi-sine, and the battery bank voltage is stepped up by a transformer.

Solar PV: a panel's open-circuit voltage appears in sunlight with no load; short-circuit current is measured with a clamp meter; MPPT charge controllers extract maximum power.

Battery charging: the charging voltage for a 12 V lead-acid battery is about 13.8–14.4 V; gassing and heating indicate overcharging.

Standard symbols: a fixed resistor is a rectangle, a capacitor two parallel lines, an inductor a coil of loops, a lamp a circle with a cross, and a fuse a rectangle with a line through it.

A single-line diagram shows the power path with one line for three phases; a wiring diagram shows every conductor and terminal number.

In a schematic, lines crossing without a dot are not connected; a dot marks a junction. This convention must be followed for a drawing to be read correctly.

Circuit numbering: terminals are labelled L (line), N (neutral), E (earth); a two-way switch is labelled COM, L1, L2.

A ladder diagram places the control circuit between two vertical rails; the rung is read left to right, with the load on the right and contacts to the left.

Scale and layout: a wiring plan is drawn to scale using the building's floor plan, with the distribution board position and circuit runs marked.

A truth table for a two-way switch circuit: output is ON when either switch is in the opposite position from the other, which is the XOR function.

Indian Electricity Rules require that no wiring work be done on a live line above 250 V without a permit and a second person present.

Permit-to-work system: the isolation is locked and tagged, the line is proved dead, and the permit is signed by the authorised person before work starts.

PPE for electrical work: insulated gloves rated for the voltage, safety shoes, helmet, and arc-rated clothing where switching operations are performed.

5S workplace practice: sort, set in order, shine, standardise, sustain; it is the base of shop-floor discipline and is assessed in industrial visits.

Lockout-tagout (LOTO): each worker applies a personal lock to the isolation point; only the person who applied it removes it.

Communication in a team: report faults with the equipment tag number, symptom, and time; a shift handover records the same three items.

First aid and emergency response: know the location of the nearest first-aid box, fire extinguisher, and emergency contact, and the assembly point.

Resume and interview basics: state the trade qualification, list the tools and machines handled, and give one concrete example of a fault you diagnosed.

A small electrical contracting business needs a licence under the state electricity rules; the licence category depends on the voltage of the installations handled.

Costing: total job cost = material + labour + overhead + contingency; the quotation adds profit margin, usually 10–20% on cost.

Break-even quantity = fixed cost / (selling price per unit − variable cost per unit); below this quantity the business makes a loss.

Working capital covers day-to-day purchases and wages; it is not the same as the capital spent on tools and vehicles (fixed capital).

GST registration is required once turnover crosses the prescribed threshold; invoices must show GSTIN, HSN/SAC code, and tax rate separately.

Customer acquisition for an electrician: local referrals, a Google business listing, and tie-ups with builders and appliance dealers are the common low-cost routes.

Record keeping: a simple cash book, a stock register for cable and fittings, and a job register with customer name, date, and work done support both tax and warranty claims.

Risk control: take advance payment for material on large jobs, use written estimates, and keep a warranty clause for workmanship separate from the product warranty.

E-waste contains lead, mercury, cadmium and brominated flame retardants; it must go to authorised recyclers, never to general municipal waste.

Used lead-acid batteries are covered by the Battery Waste Management Rules and must be returned to the dealer or an authorised recycler.

Fluorescent tubes and CFLs contain mercury vapour; they must not be broken and should be stored in a closed container until collected.

Electrical safety signs: danger signs are red, warning signs yellow, mandatory signs blue, and safe-condition signs green.

Occupational hazards in the trade: electric shock, arc flash burns, falls from ladders, and musculoskeletal strain from lifting; each needs a specific control.

Hearing and dust protection: drilling and grinding exceed safe noise levels, so ear plugs and a dust mask are required during those tasks.

Energy conservation: replace incandescent lamps with LED, use occupancy sensors in corridors, and correct power factor with capacitor banks to reduce line losses.

Asbestos and old insulation in rewiring work must be treated as hazardous; damp it before removal and use a respirator, not a simple cloth mask.

Ohm's law: V = I × R; power P = V × I = I²R = V²/R. In a series circuit current is common, in a parallel circuit voltage is common.

Conductors obey V = IR linearly; the resistance of a metallic conductor rises with temperature (positive temperature coefficient), while carbon and electrolytes show a negative coefficient.

Kirchhoff's laws: the algebraic sum of currents at a node is zero (KCL); the algebraic sum of emfs and drops around a closed loop is zero (KVL).

AC quantities: RMS value = peak/√2 = 0.707 × peak; average value of a sine wave = 0.637 × peak; form factor = 1.11; peak factor = 1.414.

Frequency f = 1/T; for a 50 Hz Indian supply the period is 20 ms. Inductive reactance XL = 2πfL; capacitive reactance XC = 1/(2πfC).

Three-phase relations: line voltage = √3 × phase voltage in star; line current = √3 × phase current in delta; power = √3 × VL × IL × cos φ.

First aid for electric shock: isolate the supply first, never touch the victim with bare hands, then assess breathing and call for medical help; use the recovery position if unconscious but breathing.

Fire classes: Class A solid, B liquid, C gas, D metal; CO2 extinguishers are preferred for live electrical fires because the agent is non-conducting and leaves no residue.

Earth-leakage protection: an ELCB/RCCB rated 30 mA trips within milliseconds and protects people; MCBs protect wiring against overload and short circuit but not against small leakage currents.

Copper: resistivity about 1.72 × 10⁻⁸ Ω·m, excellent conductivity, used for house wiring and windings; annealed copper is softer and more ductile than hard-drawn.

Aluminium: resistivity about 2.8 × 10⁻⁸ Ω·m, about 60% of copper's conductivity by volume but lighter, so it is used for overhead transmission conductors such as ACSR.

Insulating classes by temperature: Class Y 90 °C, A 105 °C, E 120 °C, B 130 °C, F 155 °C, H 180 °C, C above 180 °C.

Dielectric strength is the maximum voltage per unit thickness an insulator withstands without breakdown; measured in kV/mm and falls with moisture and heat.

Magnetic materials: soft iron and silicon steel have high permeability and low hysteresis loss (cores); hard steel and alnico retain magnetism (permanent magnets).

Eddy-current loss is reduced by laminating cores; hysteresis loss is reduced by using silicon steel, which narrows the B-H loop.

PVC is used for general wiring insulation up to about 70 °C; XLPE withstands higher temperatures and is used for power cables; rubber is used for flexible cords.

Soldering materials: tin-lead 60/40 melts near 190 °C; lead-free solder melts higher; flux removes oxide and rosin flux is preferred for electrical joints.

Ammeter is connected in series and has very low resistance; voltmeter is connected in parallel and has very high resistance; a meter with the wrong connection can short the supply.

An ammeter shunt extends range: Rshunt = Rm / (n − 1), where n is the multiplying factor. A series multiplier for a voltmeter: Rmult = Rm(n − 1).

A megger (insulation resistance tester) applies a high DC voltage and reads in megohms; a healthy 230 V domestic installation should read at least 1 MΩ to earth.

A multimeter in continuity mode uses its internal battery and buzzer; the circuit must be dead before testing resistance or continuity.

A clamp meter measures current by the magnetic field around a conductor and needs no breaking of the circuit; it reads only one conductor at a time.

Wattmeter has a current coil (in series) and a pressure/voltage coil (in parallel); incorrect polarity of the voltage coil makes the pointer deflect backwards.

An energy meter (kWh meter) is calibrated by counting revolutions; energy = (revolutions × 3600) / (meter constant in rev/kWh) in joules when time is in seconds.

Hand tools: a wire stripper sizes the conductor diameter; a crimping tool makes permanent lugs; a hacksaw blade of 18 TPI suits conduit, 24 TPI suits thin sheet.

A digital multimeter's input impedance is typically 10 MΩ, so it reads nearly true voltage; an analog meter with low ohms-per-volt loads the circuit and reads low.

Cleat wiring uses porcelain cleats and is cheap but temporary; casing-and-capping is surface protection; concealed conduit is required in modern construction because wiring is hidden and protected.

Conduit fill: the total cross-section of conductors should not exceed about 40% of the conduit internal area, so conductors can be drawn without damage.

A batten holder, ceiling rose, and pendant use three-core flexible cable; the earth wire must be connected even if the holder is of insulated body.

Loop-in (joint box) system is preferred over the old joint-box system because it keeps joints accessible at ceiling roses and switches rather than buried in walls.

Two-way switching needs three-core cable between the two switches (common, L1, L2); a staircase light controlled from two points uses two two-way switches.

A one-way switch has two terminals; an intermediate switch has four terminals and is used for control from three or more points.

Domestic load estimation: lighting circuits are wired in 1.5 mm² cable protected at 6 A; power circuits in 2.5 mm² protected at 16 A; a 4 mm² cable suits 20–25 A.

Wire colour convention (Indian practice): phase red/yellow/blue, neutral black, earth green; older installations may use red phase, black neutral, green earth throughout.

Insulation resistance is measured between conductors and between each conductor and earth with all switches on and loads disconnected; the minimum acceptable value is 1 MΩ.

A socket outlet is rated 6 A or 16 A; the 16 A socket is used for heavy appliances and is wired on a separate circuit with its own MCB.

A ceiling rose has terminals for phase, neutral and earth; the pendant flex must be supported by the rose, not by the terminals.

MCB ratings are chosen one step above the circuit design current; an MCB of type B trips at 3–5 times rated current, type C at 5–10 times.

A distribution board should have a separate earth bar, neutral bar and phase busbar; the main switch must disconnect phase and neutral simultaneously in a two-pole device.

Earthing: plate or pipe earth electrode is buried at least 2.5–3 m deep; earth resistance should be below 1 Ω for a substation and below 5–8 Ω for domestic installations.

A fan regulator in series with the fan reduces voltage; electronic (triac) regulators are more efficient than resistive wire-wound regulators.

A bell push is a momentary switch; the bell circuit uses a step-down transformer or a battery so that low voltage reaches the push button.

When mounting a switchboard, the switch is placed about 1.2 m above floor level and the socket about 0.3 m above the floor, with phase on the right-hand terminal.

An electric iron uses a nichrome element and a bimetallic thermostat; the iron not heating usually means an open element or a faulty thermostat contact, checked with a continuity tester.

A mixer-grinder's universal (series) motor has field and armature in series; sparking at the brushes indicates worn brushes, a dirty commutator, or a shorted armature.

An immersion rod or geyser element is checked by measuring resistance across its terminals; a reading of infinity means the element is open, and a low reading to the body means leakage to earth.

An electric fan with a capacitor-run motor that hums but does not start usually has a failed capacitor; a shorted capacitor can blow the fuse.

A refrigerator compressor is a sealed unit; the most common electrical faults are a burnt PTC starter, an open overload protector, and a faulty thermostat, not the compressor itself.

A washing machine's motor may be a capacitor-start induction motor; a blown fuse, faulty lid switch, or open timer contact stops the cycle before the motor runs.

Microwave ovens store lethal charge in the high-voltage capacitor even after unplugging; the capacitor must be discharged through a resistor before any servicing.

Heating appliances: a 1000 W iron on 230 V draws about 4.3 A; the element resistance is V²/P ≈ 53 Ω; the plug and flex must be rated above this current.

Transformer EMF equation: E = 4.44 f N Φm; the ratio V1/V2 = N1/N2 = I2/I1 for an ideal transformer.

Transformer losses: copper (I²R) losses vary with load and are found by the short-circuit test; iron (core) losses are constant and found by the open-circuit test.

A transformer works only on AC; it cannot change the frequency, and it does not change the power (apart from losses).

DC motor back EMF: Eb = V − IaRa; torque T ∝ ΦIa; a series motor must never be started without load because its speed rises dangerously.

Induction motor slip s = (Ns − N)/Ns; synchronous speed Ns = 120f/P; a 4-pole motor on 50 Hz has Ns = 1500 rpm.

Star-delta starter reduces starting current to one-third of the direct-on-line value; a direct-on-line starter is used only for small motors.

DC generator EMF: Eg = (PΦNZ)/(60A) where P is poles, Z conductors, N rpm, A parallel paths; the commutator converts armature AC to external DC.

Alternator frequency f = PN/120, where N is rpm and P is the number of poles; a 2-pole alternator at 3000 rpm gives 50 Hz.

Motor protection: a thermal overload relay protects against sustained overload, while a fuse or MCCB protects against short circuit; both are needed.

Lead-acid cell: nominal emf about 2 V per cell; a 12 V battery has six cells in series; fully charged specific gravity of electrolyte is about 1.28 and discharged about 1.15.

During discharge, lead-acid plates convert to lead sulphate; during charging the reactions reverse, water is electrolysed near full charge and must be topped up with distilled water only.

Battery capacity is rated in ampere-hours (Ah) at a stated discharge rate; a 100 Ah battery can deliver 5 A for about 20 hours at the 20-hour rate.

Efficiency: Ah efficiency = (Ah out)/(Ah in); Wh efficiency is always lower because the discharge voltage is lower than the charge voltage.

Li-ion cells have a nominal 3.6–3.7 V per cell and must never be overcharged or deep-discharged; a protection circuit or BMS is mandatory.

A UPS with an inverter converts DC battery energy to AC; the inverter's output waveform is sine or quasi-sine, and the battery bank voltage is stepped up by a transformer.

Solar PV: a panel's open-circuit voltage appears in sunlight with no load; short-circuit current is measured with a clamp meter; MPPT charge controllers extract maximum power.

Battery charging: the charging voltage for a 12 V lead-acid battery is about 13.8–14.4 V; gassing and heating indicate overcharging.

Standard symbols: a fixed resistor is a rectangle, a capacitor two parallel lines, an inductor a coil of loops, a lamp a circle with a cross, and a fuse a rectangle with a line through it.

A single-line diagram shows the power path with one line for three phases; a wiring diagram shows every conductor and terminal number.

In a schematic, lines crossing without a dot are not connected; a dot marks a junction. This convention must be followed for a drawing to be read correctly.

Circuit numbering: terminals are labelled L (line), N (neutral), E (earth); a two-way switch is labelled COM, L1, L2.

A ladder diagram places the control circuit between two vertical rails; the rung is read left to right, with the load on the right and contacts to the left.

Scale and layout: a wiring plan is drawn to scale using the building's floor plan, with the distribution board position and circuit runs marked.

A truth table for a two-way switch circuit: output is ON when either switch is in the opposite position from the other, which is the XOR function.

Indian Electricity Rules require that no wiring work be done on a live line above 250 V without a permit and a second person present.

Permit-to-work system: the isolation is locked and tagged, the line is proved dead, and the permit is signed by the authorised person before work starts.

PPE for electrical work: insulated gloves rated for the voltage, safety shoes, helmet, and arc-rated clothing where switching operations are performed.

5S workplace practice: sort, set in order, shine, standardise, sustain; it is the base of shop-floor discipline and is assessed in industrial visits.

Lockout-tagout (LOTO): each worker applies a personal lock to the isolation point; only the person who applied it removes it.

Communication in a team: report faults with the equipment tag number, symptom, and time; a shift handover records the same three items.

First aid and emergency response: know the location of the nearest first-aid box, fire extinguisher, and emergency contact, and the assembly point.

Resume and interview basics: state the trade qualification, list the tools and machines handled, and give one concrete example of a fault you diagnosed.

A small electrical contracting business needs a licence under the state electricity rules; the licence category depends on the voltage of the installations handled.

Costing: total job cost = material + labour + overhead + contingency; the quotation adds profit margin, usually 10–20% on cost.

Break-even quantity = fixed cost / (selling price per unit − variable cost per unit); below this quantity the business makes a loss.

Working capital covers day-to-day purchases and wages; it is not the same as the capital spent on tools and vehicles (fixed capital).

GST registration is required once turnover crosses the prescribed threshold; invoices must show GSTIN, HSN/SAC code, and tax rate separately.

Customer acquisition for an electrician: local referrals, a Google business listing, and tie-ups with builders and appliance dealers are the common low-cost routes.

Record keeping: a simple cash book, a stock register for cable and fittings, and a job register with customer name, date, and work done support both tax and warranty claims.

Risk control: take advance payment for material on large jobs, use written estimates, and keep a warranty clause for workmanship separate from the product warranty.

E-waste contains lead, mercury, cadmium and brominated flame retardants; it must go to authorised recyclers, never to general municipal waste.

Used lead-acid batteries are covered by the Battery Waste Management Rules and must be returned to the dealer or an authorised recycler.

Fluorescent tubes and CFLs contain mercury vapour; they must not be broken and should be stored in a closed container until collected.

Electrical safety signs: danger signs are red, warning signs yellow, mandatory signs blue, and safe-condition signs green.

Occupational hazards in the trade: electric shock, arc flash burns, falls from ladders, and musculoskeletal strain from lifting; each needs a specific control.

Hearing and dust protection: drilling and grinding exceed safe noise levels, so ear plugs and a dust mask are required during those tasks.

Energy conservation: replace incandescent lamps with LED, use occupancy sensors in corridors, and correct power factor with capacitor banks to reduce line losses.

Asbestos and old insulation in rewiring work must be treated as hazardous; damp it before removal and use a respirator, not a simple cloth mask.