Maharashtra SSC Electrical & Hardware Installation Tech Pre-Voc/NSQF key terms

The passage of electric current through the human body, causing burns, muscle contraction, breathing stoppage or heart rhythm disturbance. Severity depends on current magnitude, path, duration and skin condition.

Deliberate connection of exposed metal parts and the supply neutral point to the general mass of earth through a low-resistance path, so fault current flows to earth and protective devices trip quickly.

Emergency procedure of repeated chest compressions, with rescue breaths if trained, used on a person who is unresponsive and not breathing normally, to keep blood and oxygen circulating until medical help arrives.

Marked container kept at the workplace holding sterile dressings, adhesive bandages, scissors, gloves, antiseptic and a burn gel, checked regularly so contents are complete and within expiry date.

Wearable items such as insulated gloves, safety goggles, helmet, rubber-soled shoes and arc-rated clothing that reduce injury risk; it supplements safe work methods but never replaces them.

Procedure of switching off a circuit, isolating the supply, then fitting a personal lock and warning tag on the isolator so nobody can re-energise the equipment while work is in progress.

The electrical potential difference between two points, measured in volts, which drives current through a circuit. It is the pressure analogy of electricity and is measured across components.

The rate of flow of electric charge past a point, measured in amperes. In a series circuit it is the same at every point; in a parallel circuit it divides among the branches.

The opposition a material offers to current flow, measured in ohms. It depends on material resistivity, length and cross-sectional area, and causes electrical energy to be converted into heat.

Relationship stating that current through a conductor equals the voltage across it divided by its resistance (I = V/R). It allows any one quantity to be calculated when the other two are known.

The rate at which electrical energy is transferred, measured in watts, equal to voltage multiplied by current. In a resistive load it can also be found as current squared times resistance.

The ratio of true power in watts to apparent power in volt-amperes in an alternating current circuit, ranging from zero to one; a low value means more current is drawn for the same useful work.

Current whose direction and magnitude reverse periodically, typically 50 times per second in Indian domestic supply. It can be changed in voltage by a transformer, which makes transmission economical.

Current that flows in one direction only, supplied by cells, batteries and rectifier circuits. It is used by electronic appliances and by some motors and control circuits.

A material such as copper or aluminium that offers low resistance and carries electric current readily because it has free electrons available to move under an applied voltage.

A material such as PVC, rubber, porcelain or bakelite that has very high resistance and prevents current from leaving the intended path, providing safety and mechanical support.

The nominal area of a conductor in square millimetres, which fixes its current-carrying capacity and voltage drop. Undersized cable overheats and damages insulation under load.

The reduction in voltage along a cable caused by its resistance when current flows. Excessive drop makes lamps dim and motors overheat, so cable length and size must be chosen carefully.

A conductor made of many thin wires twisted together, giving flexibility for use in portable appliances, conduit wiring and panel connections where a solid wire would crack or be hard to bend.

Pliers, screwdrivers and cutters with moulded or dipped insulating handles rated for a stated voltage, used for live working only within that rating and inspected for cracks before use.

Tool with sized notches that removes insulation from a conductor without nicking the metal strands; a nicked strand weakens the wire and can break or overheat at the joint.

Making a permanent electrical and mechanical joint by compressing a metal lug or ferrule onto a conductor with a crimping tool, giving a low-resistance connection that resists vibration.

General-purpose measuring instrument that selects voltage, current or resistance ranges and displays the value digitally; the correct function and range must be chosen before the probes touch the circuit.

Instrument that measures alternating current without breaking the circuit, by clamping its jaws around a single conductor and sensing the magnetic field produced by the current.

Test using a megger that applies a high direct voltage between conductors and earth to confirm insulation is sound; a low reading in megohms indicates moisture or damaged insulation.

Check made with a low-resistance ohmmeter to confirm the protective conductor path from appliance metalwork to the earth terminal has acceptably low resistance and no breaks.

Condition of an unbroken conductive path, verified with a meter on the resistance or buzzer range after the circuit is isolated; a very high reading shows an open circuit.

Instrument that generates a high test voltage, commonly 500 volts, to measure insulation resistance in megohms; the circuit must be isolated and discharged before and after testing.

Switch with one common terminal and two way terminals, used in pairs so a lamp can be controlled from two positions, as on a staircase, using strapper wires between the switches.

Single-pole switch that makes or breaks one circuit conductor, used for simple lamp and fan control; it has two terminals and is rated by current and voltage.

Conductor that carries current from the supply to the load and remains at dangerous potential to earth; it must pass through the switch, never the neutral, for safety.

Return conductor of a supply system, connected to the earthed neutral point of the transformer; it completes the circuit and is normally near earth potential but must still be treated as live.

Automatic switch that trips on overload by thermal action and on short circuit by magnetic action, protecting cable and equipment; it is resettable and rated in amperes and breaking capacity.

Protective device that trips when the current leaving through live and returning through neutral differ by a small set amount, detecting earth leakage and reducing shock risk.

Protective device containing a metal element that melts and opens the circuit when current exceeds its rating; it must be replaced with the same rating and type after operation.

Expanding plastic or fibre sleeve inserted into a drilled hole in masonry so a screw grips firmly; the drill size and screw gauge must match the plug for a sound fixing.

Numbering system describing the diameter of a screw, where a higher gauge number means a thinner screw; it determines the pilot hole and plug size required for fixing.

Heavy-duty fixing that expands inside concrete or brick to hold brackets, boards and frames; its load rating depends on base material strength and correct drilling depth.

Threaded fitting that grips a cable entry into a box or panel, providing strain relief and a seal so the outer sheath is not cut by the metal edge.

Instrument that records the electrical energy consumed over time, usually displayed in kilowatt-hours, and forms the basis of the consumer's electricity bill.

Unit of electrical power, equal to one joule per second, or one ampere flowing at one volt. Appliance ratings in watts indicate how much power they draw in normal use.

Drawing that shows the electrical connections between components using standard symbols, arranged for easy reading rather than to represent their physical positions on the equipment.

Standard graphical mark representing a component, such as a circle for a lamp or a break in a line for a switch, so drawings are understood the same way by every technician.

Simplified drawing that represents a three-phase or multi-wire system with one line per circuit path, showing the arrangement of supply, protection and distribution without every conductor.

Enclosure that receives the supply and divides it into final circuits, housing the main switch, busbar, miniature circuit breakers and residual current devices with a labelling schedule.

Simple diagnostic tool of a lamp in an insulated holder with two probes, used to check presence of voltage; it must be rated for the supply and never used on unknown high voltages.

Plate holding switches, sockets and regulators, mounted on a box in the wall; its metal parts must be earthed and its mounting height and position follow the wiring layout.

Standard-sized switch, socket, regulator or indicator that clips into a modular plate and box, allowing circuits to be changed or extended without replacing the whole board.

Workplace capability beyond technical knowledge, such as punctuality, teamwork, communication, problem solving and willingness to learn, which employers assess alongside trade competence.

Starting and running one's own electrical service or hardware business, involving identifying customer needs, costing work, managing tools and materials, and complying with licensing and tax rules.

Written price offer to a customer listing the scope of work, materials, labour, taxes and validity period, forming the basis of the work order and helping avoid later disputes.

Explaining faults, work done, safety precautions and costs clearly to customers, supervisors and colleagues, in speech, written reports or drawings, using correct trade terminology.