What is the difference between ET101 and I.S. 10101?

ET 101:2008 was the fourth edition of Ireland's National Rules for Electrical Installations. I.S. 10101:2020 is the fifth edition published by the NSAI on 6 March 2020. It replaced ET 101 with updated requirements including extended RCD protection, SPD selection, revised verification procedures, and new Part 7 sections for EV charging and expanded PV rules.

Is there a single national ET101 exam with a fixed number of questions?

No. I.S. 10101 knowledge is assessed through multiple routes including Verification and Certification (V&C) courses (such as City & Guilds 2407), SOLAS apprenticeship phase theory papers, and competence requirements for RECI registration. The exact question count and pass mark depend on your training provider.

Which wiring standard applies in Ireland — I.S. 10101 or BS 7671?

I.S. 10101:2020 is the Irish National Rules for Electrical Installations. BS 7671 is the UK wiring regulations and does not apply in the Republic of Ireland. Values such as RCD requirements, disconnection times, and certification procedures follow I.S. 10101 and the Safe Electric scheme.

What RCD rating is required for socket-outlet circuits under I.S. 10101?

General-purpose socket-outlet circuits must be protected by an RCD with a rated residual operating current not exceeding 30 mA. I.S. 10101 also extended 30 mA RCD protection to domestic lighting final circuits, which was not a general requirement under ET 101.

Who certifies electrical installations in Ireland?

Controlled electrical works must be certified by a Registered Electrical Contractor (REC) or a Safe Electric inspector. Completion certificates are issued through the Safe Electric online certification system. The CRU regulates the scheme; the NSAI publishes the technical standard but does not issue installation certificates.

Is this free I.S. 10101 practice test useful for the ET101 exam?

Yes. Our 100 practice questions cover all I.S. 10101:2020 chapters with correct Irish terminology, values, and Safe Electric context. Every answer includes a teaching explanation plus free daily AI tutor help. All content is free and updated for 2026.

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104+ Free I.S. 10101 / ET101 Wiring Rules Practice Questions

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Key Facts: I.S. 10101 / ET101 Wiring Rules Exam

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I.S. 10101:2020

Current National Standard

NSAI

1000 V AC

Maximum Voltage Scope

I.S. 10101

230/400 V

Irish Supply

ESB Networks

30 mA

RCD for Sockets & Domestic Lighting

I.S. 10101

8 chapters

I.S. 10101 Structure

NSAI

I.S. 10101:2020 is Ireland's National Rules for Electrical Installations, published by the NSAI and replacing ET 101:2008. It covers low-voltage installations up to 1000 V AC across eight chapters: scope and definitions, general design characteristics, protection for safety, selection and erection, verification and certification, special locations (bathrooms, pools, construction sites, EV charging, PV, and more), and energy efficiency. Ireland uses 230 V single-phase and 400 V three-phase at 50 Hz with harmonised brown/blue/green-yellow cable colours, 30 mA RCD protection for socket-outlets and domestic lighting, and Safe Electric certification for controlled works. This free prep includes 100 research-based practice questions with explanations and an AI tutor.

Sample I.S. 10101 / ET101 Wiring Rules Practice Questions

Try these sample questions to test your I.S. 10101 / ET101 Wiring Rules exam readiness. Each question includes a detailed explanation. Start the interactive quiz above for the full 104+ question experience with AI tutoring.

1What does I.S. 10101:2020 represent in the Republic of Ireland?

A.The ESB Networks connection agreement

B.The National Rules for Electrical Installations

C.The Building Regulations Part B fire standard

D.The Health and Safety Authority electrical enforcement code

Explanation: I.S. 10101:2020 is the National Rules for Electrical Installations, published by the NSAI. It sets the safety requirements for the design, erection and verification of low-voltage electrical installations in Ireland and replaced ET 101:2008.

2Which organisation publishes Ireland's National Rules for Electrical Installations?

A.SOLAS

B.The Commission for Regulation of Utilities (CRU)

C.The National Standards Authority of Ireland (NSAI)

D.ESB Networks

Explanation: The NSAI publishes I.S. 10101 through its Electro Technical Committee ETC/TC 2. Safe Electric enforces compliance with the rules, but the standard itself is an NSAI document.

3I.S. 10101:2020 replaced which previous edition of the Irish national wiring rules?

A.BS 7671:2018

B.ET 101:2008

C.IEC 60364-1

D.AS/NZS 3000

Explanation: I.S. 10101:2020 is the fifth edition and replaced ET 101:2008, the fourth edition. Irish electricians must work to I.S. 10101, not the UK's BS 7671.

4The voltage scope of I.S. 10101 covers electrical installations up to:

A.230 V AC only

B.1000 V AC

C.11 kV

D.Low voltage and high voltage without limit

Explanation: I.S. 10101 specifies requirements for low-voltage electrical installations up to 1000 V AC. It addresses design, erection and verification within that voltage range.

5Under I.S. 10101, the remit of the National Rules for Electrical Installations ends at:

A.The meter tails only

B.The electric socket or isolator supplying the equipment

C.The appliance internal wiring

D.The ESB substation transformer

Explanation: The scope covers the fixed wiring installation up to the socket-outlet or isolator. Equipment plugged in or wired beyond that point is covered by separate product standards, not I.S. 10101.

6In I.S. 10101:2020, what were formerly called "Parts" in ET 101:2008 are now labelled as:

A.Sections

B.Chapters

C.Volumes

D.Schedules

Explanation: I.S. 10101 relabelled the former Parts 1–7 as Chapters to align with IEC and CENELEC document structure and improve readability. The technical content follows the same logical framework.

7Which body operates the Safe Electric scheme that ensures electrical contractors comply with I.S. 10101?

A.The NSAI

B.The Health and Safety Authority

C.The Commission for Regulation of Utilities through its designated safety supervisory body

D.An Garda Síochána

Explanation: The CRU regulates restricted and controlled electrical works in Ireland. Safe Electric is the designated safety supervisory body that registers electrical contractors and inspects compliance with the National Rules.

8A "Registered Electrical Contractor" (REC) under the Safe Electric scheme is authorised to:

A.Publish amendments to I.S. 10101

B.Carry out controlled electrical works and issue completion certificates where competent

C.Set the national supply voltage

D.Approve NSAI standards without inspection

Explanation: Registered Electrical Contractors are registered by Safe Electric to undertake controlled works and, where qualified, certify that installations comply with I.S. 10101. They do not write or amend the standard itself.

9The nominal supply voltages commonly used for utilisation in Irish installations are:

A.110 V single-phase and 220 V three-phase

B.230 V single-phase and 400 V three-phase at 50 Hz

C.120 V single-phase and 208 V three-phase at 60 Hz

D.240 V single-phase and 415 V three-phase at 50 Hz

Explanation: Irish installations are designed for a 230 V single-phase and 400 V three-phase supply at 50 Hz from ESB Networks. These values are the basis for disconnection times, voltage drop and equipment ratings.

10Chapter 3 of I.S. 10101 requires the designer to assess which of the following for every installation?

A.Only the colour of switch plates

B.Maximum demand, earthing arrangement, external influences and maintainability

C.The brand of consumer unit preferred by the client

D.The electrician's hourly rate

Explanation: General characteristics include maximum demand and diversity, conductor arrangement and earthing, external influences (such as water, heat and mechanical damage), compatibility, maintainability and continuity of service.

About the I.S. 10101 / ET101 Wiring Rules Practice Questions

Verified exam format metadata for National Rules for Electrical Installations (I.S. 10101:2020 / ET101) — Ireland is pending. The practice questions above remain available while official exam length, timing, passing score, fee, and administrator details are reviewed.