AM2 / AM2S flashcards

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

Proving unit

A known voltage source used to confirm that a voltage indicator operates correctly before and after testing a circuit for dead.

GS38 voltage indicator

Safety standard for test probes requiring fused leads, finger guards and limited exposed metal, used for proving dead on low-voltage systems.

Hierarchy of control

Risk control order: eliminate the hazard, substitute, apply engineering controls, use administrative controls, then PPE as the last resort.

EAWR 1989

Electricity at Work Regulations require work to be dead where reasonably practicable; live work only if justified, authorised and controlled.

Lock-off device

A lockable isolation device applied to a breaker or switch so that the circuit cannot be re-energised while a person works.

Reference Method C

Installation method for flat twin-and-earth cable clipped direct to a surface, used to select current-carrying capacity from BS 7671 tables.

Correction factor Ca

Factor applied to cable current-carrying capacity for ambient temperature; it is tabulated in BS 7671 and reduces capacity as temperature rises.

Main protective bonding

Connection of extraneous conductive parts to the main earthing terminal; minimum 6 mm² copper, or 10 mm² for PME supplies.

Ring final circuit

A 32 A socket circuit wired in 2.5 mm² line and neutral with a 1.5 mm² CPC, limited to 100 m² floor area.

Conduit fill factor

BS 7671 limits conductor space in conduit to 40 percent of internal cross-sectional area to allow drawing in and heat dissipation.

CPC sizing rule

For line conductors up to 16 mm² the circuit protective conductor may be the same size; larger lines follow Table 54.7.

Insulation resistance test

Measured at 500 V DC for 230/400 V circuits; the minimum acceptable value is 1 MΩ per BS 7671 Table 64.1.

R1 plus R2 test

Continuity measurement of line and protective conductors connected together, confirming CPC continuity and giving earth fault loop resistance.

Ring final cross-connection

Connect line to neutral and neutral to line at the board; expected R1 + R2 equals (r1 + r2) divided by four.

External earth loop impedance

Ze is measured at the origin with main bonding disconnected and is used to confirm the supply earth fault loop path.

RCD five-times test

At five times rated residual current a 30 mA RCD should trip within 40 ms; at rated current it should trip within 300 ms.

Electrical Installation Certificate

Issued for new installation work or major alteration, supported by schedules of test results and signed declarations of design, construction and verification.

Prove dead sequence

Test between line and neutral, line and earth, and neutral and earth with an approved two-pole indicator, then re-prove the indicator.

Borrowed neutral

A neutral connected to a different circuit's line conductor, causing the isolated circuit to remain live; check by isolating and testing all conductors.

Multi-lock hasp

A lockout accessory allowing several workers to fit personal padlocks to one isolation point so the supply cannot be restored.

Isolation point

The device used to disconnect all live conductors from the supply; it must be identified, locked and proved dead before work.

Backfeed risk

Unexpected energisation from generators, PV, UPS or adjacent circuits; isolate all sources and prove dead at the point of work.

Half-split method

Fault-finding technique that divides a circuit into sections and tests each half to locate an open circuit or low insulation fault.

High resistance joint

A loose or corroded connection causing volt drop and heat; identified by continuity resistance and voltage-drop tests under load.

Nuisance RCD tripping

Cumulative earth leakage from several circuits or appliances exceeding the RCD threshold; isolate circuits and test leakage individually.

Short circuit fault

A low-resistance path between line and neutral or earth causing immediate high current and protective device operation.

Voltage drop formula

Voltage drop in volts equals millivolts per amp per metre times design current times cable length divided by 1000.

Part P notification

In England and Wales, notifiable domestic electrical work must be notified to building control or carried out by a registered competent person.

BS 7671 status

The IET Wiring Regulations are not statute law but provide the accepted standard for complying with electricity safety legislation.

Health and Safety at Work Act

1974 Act imposing duties on employers and self-employed persons to ensure health, safety and welfare of employees and others affected.

CDM 2015

Construction Design and Management Regulations require coordination of health and safety throughout a construction project, including electrical risks.

Part M

Building Regulation requiring reasonable provision for access and use of buildings, affecting socket, switch and consumer unit heights.