I.S. 10101 / ET101 Wiring Rules study guide
I.S. 10101 / ET101 Wiring Rules · Work through your exam, one topic at a time.
10101 is the Irish national standard for electrical installations, the document most electricians still call ET101. It sets out how a installation must be designed, selected, erected, inspected and tested so that people, livestock and property are protected against shock, fire, overcurrent and thermal damage. The I.S. 10101 / ET101 Wiring Rules study guide has 8 sections and about 3,261 words.
01Scope, Fundamental Principles and Definitions
ET10101 is the national wiring rules for fixed installations. Its scope runs from the point of supply (origin of the installation) through final circuits to the points of use, and it applies to new work, alterations and additions.
339 words, about 2 min02General Characteristics and Assessment of General Characteristics
Before selecting cables you must characterise the installation. The classic sequence is: (1) maximum demand and diversity; (2) earthing arrangement and supply characteristics; (3) division into circuits; (4) protective measures; (5) external influences; (6) cross-sectional area selection; (7) protective device selection; (8) voltage drop; (9) protective conductor sizing.
349 words, about 2 min03Protection for Safety: Electric Shock
Protection against electric shock has two independent layers: basic protection (against contact with live parts in normal service) and fault protection (against contact in a fault). Both must normally be present; where one measure provides both, it is called reinforced protection (e.g.
327 words, about 2 min04Protection for Safety: Thermal Effects, Overcurrent and Surge
Overload is a current in an otherwise healthy circuit; short circuit is a fault between live conductors (or to earth). Protection must operate before thermal damage occurs.
333 words, about 2 min05Selection and Erection of Wiring Systems
A wiring system is chosen to suit external influences (water, dust, impact, temperature, corrosion, flora/fauna), the building construction, and maintainability. You must also consider electromagnetic compatibility, fire performance, and the skill available for maintenance.
330 words, about 2 min06Cables and Conductors
Copper is standard; aluminium needs larger cross-section and careful termination. Cross-sectional area is chosen so that: 1.
304 words, about 2 min07Earthing Arrangements, Protective Conductors and Bonding
The system type (TN-S, TN-C-S, TT, IT) determines how fault current returns and therefore what protection is needed. In TN-S the earth is a separate conductor from the source; in TN-C-S the neutral and earth are combined in the supply and separated at the origin (PEN); in TT the installation uses a local electrode and needs an RCD.
339 words, about 2 min08Switchgear, Controlgear, Isolation and Switching
Switching devices serve distinct purposes and questions test whether you can tell them apart: Isolation : to cut off for maintenance/safety, with a visible or reliably indicated gap and lockable. Emergency switching : to remove danger quickly (e.g.
940 words, about 5 min