Israel Electrician Licensing Exam flashcards

32 cards. Read the term and the definition here. The deck at the top of this page is optional.

Ohm's law

For a resistive circuit, voltage equals current multiplied by resistance (U = I × R). Power equals voltage times current, also I²R or U²/R.

Three-phase power formula

For a balanced three-phase load, active power equals √3 times line voltage times line current times power factor. Reactive power uses sine of the phase angle instead.

Inductive reactance

Opposition to alternating current from inductance, calculated as two pi times frequency times inductance. It rises with frequency, so higher harmonics see greater impedance.

Power factor

Ratio of active power to apparent power, equal to cosine of the phase angle between voltage and current. Low values increase current for the same useful power.

Kirchhoff's current law

The algebraic sum of currents entering and leaving any node in a circuit equals zero. It expresses conservation of charge at a junction.

Design current inequality

The circuit design current must not exceed the device rating, which must not exceed the cable capacity. This ordering ensures the cable is protected from overload.

Voltage drop allowance

Final circuits are commonly limited to about three percent drop, and the whole installation to about five percent from origin. Confirm values in SI 100.

Adiabatic short-circuit check

The cable withstands a fault if k squared times cross-section squared is at least the fault current squared times clearing time. k depends on conductor and insulation.

Protective conductor sizing rule

The protective conductor matches the phase conductor up to 16 square millimetres, is 16 square millimetres up to 35, and half the phase size above that.

Cable correction factors

Tabulated current capacity must be multiplied by factors below one for ambient temperature, grouping, thermal insulation and installation method before comparing with the design current.

MCB trip types

Type B trips at three to five times rated current, type C at five to ten, and type D at ten to twenty. The type is chosen to tolerate expected inrush current.

RCD versus RCBO

An RCD detects residual current only and needs separate overcurrent protection. An RCBO combines residual current and overcurrent protection in a single device.

RCD 30 mA protection

A 30 milliampere residual current device provides additional protection against electric shock and is required for socket circuits and wet locations under SI 100.

TN-S earthing system

The supply provides separate neutral and protective conductors all the way from the source. Earth fault current returns through the metallic protective conductor.

TT system disconnection

The installation has its own earth electrode independent of the supply neutral. Disconnection relies on an RCD, with electrode resistance not exceeding 50 volts divided by trip current.

Earth-fault loop impedance

The total impedance of the fault path. It must be low enough that the protective device trips within the required disconnection time at the nominal voltage.

Main equipotential bonding

Connection of incoming metallic water, gas and structural services to the main earthing terminal at the origin, keeping all accessible metal at similar potential.

Five safety rules

Disconnect the supply, secure against reconnection, verify absence of voltage, earth and short-circuit, and protect adjacent live parts before beginning work.

Ventricular fibrillation threshold

Currents above roughly 30 milliamperes through the body can cause ventricular fibrillation. This is why 30 milliampere RCDs are used for additional protection.

First aid for electric shock

Isolate the supply safely, call emergency services, check breathing and pulse, begin CPR if trained, and use an automated external defibrillator if available.

Lockout tagout

Each worker applies a personal lock and tag to the isolation point. Only the person who applied a lock removes it, following the documented procedure.

SI 100 scope

The Israeli national electrical code governing low-voltage installation requirements, including protection, earthing, cable selection and inspection obligations for electricians.

SI 900 scope

The Israeli standard covering electrical installations in residential buildings, setting requirements for dwelling circuits, socket outlets and protective measures.

Israeli supply characteristics

Low-voltage supply is 230 volts phase to neutral and 400 volts phase to phase at 50 hertz, with a combined neutral-earth arrangement at the origin.

Electrician licensing classes

Israeli law defines licence classes such as practical electrician, electrician and electrical engineer, each permitting different scopes of installation work and supervision.

Insulation resistance test

A DC test voltage, typically 500 volts, is applied between conductors and earth. A healthy low-voltage installation reads at least one megohm.

Continuity testing

A low-resistance ohmmeter verifies protective conductors and ring circuits. Test leads are nulled first so their resistance does not distort the reading.

RCD trip time test

A calibrated tester applies residual current at rated and five times rated sensitivity, recording trip times to confirm the device operates within specified limits.

Polarity check

Verification that the line conductor is switched and connected to the correct socket terminal. Reversed polarity is a common and dangerous installation fault.

Synchronous speed

The speed of the rotating magnetic field, equal to 120 times frequency divided by the number of poles. A four-pole motor on 50 hertz runs at 1500 rpm.

Induction motor slip

The fractional difference between synchronous speed and actual rotor speed. Slip increases with load and is necessary for torque production.

Star-delta starting

A starting method that reduces starting current and torque to one third of direct-on-line values. It suits loads that can accelerate with reduced torque.