18th Edition · Plumbing revision

Electrical — 18th Edition revision notes

BS 7671: shock protection and ADS, earthing and bonding, overcurrent and RCDs, cable selection, inspection and testing, special locations and safe isolation.

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Principles & definitions

Lesson

BS 7671 Status, Voltage Bands and Key Definitions

How BS 7671 fits with UK law, the ELV and LV voltage bands, SELV, PELV and FELV, and the core definitions used throughout the Wiring Regulations.

Protection against electric shock

Lesson

Protection Against Electric Shock: ADS, Disconnection Times and RCDs

How automatic disconnection of supply protects against electric shock, the maximum disconnection times, and the roles of the 30 mA RCD and SELV.

Earthing & protective bonding

Lesson

Earthing systems and protective bonding

How TN-S, TN-C-S (PME) and TT systems earth an installation, and why we bond extraneous-conductive-parts.

Overcurrent, RCDs & devices

Lesson

Overcurrent protection, RCDs and devices

Overload versus fault current, the Ib <= In <= Iz rule, MCB tripping curves, breaking capacity and RCD types.

Selection & erection: cables

Lesson

Selection and Erection of Cables: Ratings, Colours and Concealed-Cable Protection

How to identify conductors and coordinate a cable with its protective device, including derating, voltage drop, insulation temperatures, IP ratings and concealed-cable protection.

Inspection & testing

Lesson

Inspection and Testing: Initial Verification, Dead and Live Tests, Certificates

The order and purpose of initial verification, the dead and live test sequences, and which certificate or EICR code applies.

Special locations

Lesson

Locations Containing a Bath or Shower: Zones and Protection (Section 701)

Section 701 rules for rooms containing a bath or shower: the zones, 30 mA RCDs, IP ratings, SELV limits and when supplementary bonding may be omitted.

Safe isolation

Lesson

Safe Isolation: Proving a Circuit Dead under the EAWR 1989

Safe isolation under the Electricity at Work Regulations 1989 using the GS38 prove-test-prove method and suitable test instruments.

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