I.S. 10101 explained: Ireland's National Rules for Electrical Installations in homes

What is I.S. 10101 and is it the law in Ireland?

I.S. 10101, “National Rules for Electrical Installations”, is published by the National Standards Authority of Ireland (NSAI). It is the fifth edition of the Irish wiring rules and replaced ET 101:2008. Like BS 7671 in the UK and most European wiring standards, it is built on the international IEC / HD 60364 series, with Irish national choices on top.

A standard is not an Act, but in practice I.S. 10101 is compulsory for anyone certifying domestic work. Under the Electricity Regulation Act 1999 (as amended) and the decisions of the Commission for Regulation of Utilities (CRU), “Restricted Electrical Works” may only be carried out by a Registered Electrical Contractor (REC). The CRU's designated body, Safe Electric (previously known as RECI), registers these contractors and requires every certificate they issue to show compliance with I.S. 10101.

ESB Networks supply and earthing: 12 kVA and TN-C-S

Irish homes are supplied at 230 V single-phase, 50 Hz. The rules of connection are set by the ESB Networks National Code of Practice for Customer Interface (version 6.2, June 2025), which every installer must follow. The standard domestic connection has a Maximum Import Capacity (MIC) of 12 kVA, and the customer's main protective device may not exceed 63 A. The meter box on the outside wall is a standard 600 × 400 × 155 mm enclosure with its bottom 1,000 to 1,200 mm above finished ground level.

TN-C-S is the standard earthing arrangement for every new low-voltage ESB connection: the customer's main protective conductor is linked to the network neutral at the main supply point, at a single point, and the main earthing terminal sits outside the sealed ESB enclosure. Many existing homes are TT, with their own earth electrode; a REC can convert them to TN-C-S where the network equipment allows it, without breaking the ESB seals, and must certify the change.

Final circuits: radials, rings, lighting and cookers

Ireland uses the same 13 A fused plug and socket system as the UK (I.S. 401 plugs and I.S. 411 sockets, derived from BS 1363). The circuit layouts are therefore familiar to anyone who knows BS 7671, with one difference in habit: most Irish socket circuits are 20 A radials in 2.5 mm² cable, and the ring final circuit, standard in Britain, is used less often.

I.S. 10101 is a paid NSAI document and its domestic circuit rules (Annex 55A) are not publicly summarised. Apart from the lighting rule, which three Irish sources agree on, the values below are usual practice reported by Irish distributors and installers, used by Circuia as defaults and flagged for confirmation.

• Rings are allowed at 32 A in 2.5 mm² (no 20 A rings). Spurs and fused connection units follow the same logic as in the UK, but that has not been confirmed against Annex 55A.
• Cookers above 10 kW must have their circuit calculated (Annex 55A rule 3.3, cited by Safe Electric), and the cooker isolator must be able to switch the full load.
• Cables must meet the fire-reaction class Dca-s2,d2,a2 at least (I.S. EN 50575, regulation 527).

RCDs, AFDDs and surge protection under I.S. 10101

The most visible change in 2020 was 30 mA RCD protection for lighting circuits in dwellings (411.3.4), on top of the long-standing requirement for socket-outlets up to 32 A (411.3.3). In practice a new Irish consumer unit protects every final circuit, most often with one RCBO per circuit or a “dual RCBO” for lighting, as manufacturers recommend.

Two points remain open in public sources: whether every bathroom circuit and every cable buried less than 50 mm in a wall must be RCD-protected (as in the UK and HD 60364), and whether an SPD is effectively mandatory in a single house. Circuia assumes RCD protection everywhere and adds a type 2 SPD to the board by default, which is the cautious reading.

Bathrooms and shower rooms (Section 701)

Irish bathrooms follow the zone system of HD 60364-7-701, as in the UK. The dimensions below come from secondary Irish sources and match the harmonised document; the distance for 230 V sockets is where Ireland is reported to differ from the UK, and it is the least certain value on this page.

Consumer unit (distribution board) rules

• The board complies with I.S. EN 61439-1 and -3. The enclosure may be metal or non-metallic material that passes the glow-wire test of IEC 60695-2-11 (530.6.1). Unlike the UK, there is no blanket “non-combustible” rule.
• The top of the highest protective device must be no more than 2.15 m above the floor (reported by two Irish distributors).
• The main isolator switches both line and neutral on a single-phase domestic board.
• The main protection stays within the MIC: 63 A on a standard 12 kVA connection.

Neither I.S. 10101 (as publicly summarised) nor the Irish Building Regulations set a minimum number of sockets or lighting points per room. Plan by use: several double sockets per bedroom and living room, a generous number above the kitchen worktop, and dedicated outlets for fixed appliances.

EV chargers: Section 722 and the ESB 12 kVA connection

• Section 722 was entirely rewritten by A1:2024 (wired and wireless charging, RCD selectivity between the charger and the upstream devices).
• Each charger has its own circuit and RCD: type A is accepted when the charger has built-in 6 mA DC detection, otherwise type B.
• On a TN-C-S supply, an outdoor charger needs protection against a broken PEN conductor: either a dedicated earth electrode (TT) or a charger with certified open-PEN detection. The exact I.S. 10101 thresholds were not available to us.
• On a standard 12 kVA connection, a charger up to 32 A needs load management keeping the home within its MIC, or an application to ESB Networks for a higher MIC (National Code of Practice, Annex I).

Safe Electric, Registered Electrical Contractors and the Completion Certificate

Ireland does not use a third-party inspection before connection. Instead, the REC's Qualified Certifier self-certifies the work on a Safe Electric Completion Certificate, and ESB Networks connects a new installation only after it has received the validated certificate. Certificates are issued electronically.

Planning an I.S. 10101 installation with Circuia

Choose Ireland when you create the project. The editor then wires sockets as 20 A radials in 2.5 mm² by default (rings of 32 A are accepted and checked), limits lighting to 6 A on 1.5 mm², proposes RCBOs with a type 2 SPD, checks the bathroom distances, flags bedroom circuits for an AFDD and warns when an EV charger or a second shower may exceed the 12 kVA MIC. The circuit schedule, single-line diagram and bill of materials follow, ready to hand to your REC.

Open the editor set up for Ireland (free, in your browser). Working in Northern Ireland or Great Britain? See the BS 7671 guide and the overview of all standards.

Common mistakes

• ×Protecting 1.5 mm² lighting circuits at 10 A, as under ET 101: I.S. 10101 practice is 6 A.
• ×Leaving lighting circuits without 30 mA RCD protection in a new home.
• ×Fitting type AC RCDs in a new installation.
• ×Adding an EV charger or a second electric shower on a 12 kVA connection without load control or a MIC increase.
• ×Using the TN-C-S earth for an outdoor EV charger without open-PEN protection or an earth electrode.
• ×Replacing a consumer unit or adding a circuit without a REC and a Completion Certificate.
• ×Assuming UK bathroom distances apply unchanged: check the Irish value with your REC.

Frequently asked questions

Related pages

• OverviewElectrical wiring standards in Europe, country by countryHome wiring rules explained for the UK (BS 7671), Ireland (I.S. 10101), Norway, Sweden, Denmark and Finland, with the Circuia editor for each country.
• GuideBS 7671 explained: the UK wiring regulations for homes (18th Edition, A4:2026)BS 7671:2018+A4:2026 for homes: ring and radial circuits, RCD, AFDD and SPD rules, bathroom zones, EV charging, consumer units and Part P certification.
• CircuiaPricing: free, Project Pass €39, Pro €49/monthCircuia plans: Free to explore, Project Pass at €39 incl. VAT for a homeowner project, Pro at €49 excl. VAT/month and Team at €129 excl. VAT/month for electricians. 14-day trial.
• CircuiaCircuia: AI wiring plans to BS 7671 and EU standardsDraw your home or ask the AI: Circuia designs circuits and the consumer unit, checked against BS 7671, I.S. 10101 and the rules of 17 European countries.