I.S.10101 - Installation

I.S.10101 – Frequently Asked Questions

Do I have to fit surge protection?

SPDs are strongly recommended for installations that are exposed to transients, to protect sensitive and expensive electrical equipment such as TVs, washing machines, PCs, alarms etc.

Clause 443.4 of I.S.10101 states;
Protection against transient overvoltages shall be provided where the consequence caused by overvoltage could:
(a) result in serious injury to, or loss of, human life;
(b) result in interruption of public services / or damage to cultural heritage;
(c) result in interruption of commercial or industrial activity;
(d) affect a large number of co-located individuals.

For all other cases, a risk assessment shall be performed to determine if protection against transient overvoltage is required.

The risk assessment method requires entering information such as the frequency of lightning in the location, and the lengths of the HV and LV supply cables, into a mathematical formula. As this type of information can be difficult to obtain, in most cases
it is more practical to fit the surge protection device.

Does it matter where on the board I fit the surge protection device?

Yes. It should be as close to the incomer as possible, with the shortest, straightest cable links between the circuit protection device and the surge protection device.

What is an Arc Fault Detection Device?

Arc fault protection devices (AFDD) use microprocessors to identify characteristic current flow and voltage curves that indicate an arc fault and automatically trip the affected circuit.
This significantly reduces the risk of fire due to faulty conductors and connections. The protective function of the AFDD has already proven its worth internationally and has been used in Germany since February 2016.

Where do I install an AFDD?

In the consumer unit/distribution board at the origin of AC final circuits.

What are the potential hazards that AFDDs protect against?

Arc faults can be caused by all types of line faults and worn contacts;

  • Kink/break in a cable
  • Cable wear due to frequent use
  • Cable damage resulting from drilling or construction work
  • Incorrect wire stripping
  • Incorrect wire stripping
  • Incorrect bending radii
  • Loose screwed connections
  • Defective wall plugs
  • Rodents biting cables

An AFDD will trip the circuit when a potentially hazardous arc occurs, eliminating the resulting fire hazard.

How are AFDDs different to an MCB?

An AFDD is activated by both series and parallel arc faults. Unlike circuit breakers or RCDs, an AFDD does not have an electromechanical trigger but utilises electronic technology to analyse the signature (waveform) of an arc. It reliably differentiates between an arc fault and the signature (waveform) in normal switching and control events, preventing false tripping.

What type of RCD/RCCB should be used for circuits supplying EV charging equipment?

If the charging equipment is fitted with 6mA DC fault protection then it is acceptable to use type A RCD. If 6mA fault protection is not included then type B should be used. When an RCBO is being used care should be taken not to confuse the B rating of the overload protection and the B rating of the residual current protection.

Do I need to use Dca rated cable?

Yes, clause 527 of the I.S. 10101:2020 wiring rules state that the minimum rating for cables is Dca -S2, d2, a2.

What rating/type of protective device should be used for lighting circuits when wired using 1.5mmSQ cable? How many lighting circuits should be installed in a domestic dwelling and why?

The new I.S.10101 requirements state:

  • Additional protection with an RCD with a rated residual operating current not exceeding 30 mA should be provided for A.C. final circuits supplying luminaires in domestic premises.
  • An overcurrent protective device rating of 6A for 1.5mm copper cable and 10A for 2.5mm cable should be used in lighting circuits.
  • To meet this instruction, it is recommended to use a consumer unit with a ‘dual RCBO’ arrangement for lighting circuits.

Should the meter tails unit be a single pole or a double pole device?

If the enclosure used complies with the definition below and is accessible to ordinary people then it should be a 2 pole MCB;
Distribution Board – assembly containing different types of switchgear and control gear associated with one or more outgoing electrical circuits fed from one or more incoming electrical circuits, together with terminals for neutral and protective conductors.

When installing an SPD, should it be connected in series or parallel?

The surge protection device should be connected in parallel with the load, connected directly with the Phase and Neutral of the Incoming supply and to the main Earth terminal of the installation.

How often should the state of the SPD be inspected? Who should check it, and what should be done if it displays a fault?

The HSA suggests a yearly visual inspection to be carried on the board and a full inspection & testing every 5 years. That should be highlighted to the homeowner, so the SPD should be checked yearly. On the SPD you have visual indicators that turn red once they are ineffective, to fix the problem you should simply replace the cartridges on the SPD.

Can I use one AFDD to protect an entire installation?

AFDD’s should be installed at the origin of a final circuit. It is not possible to use an overall AFDD protecting a complete installation.

Can I still use the old regulations (ET101)?

It is recommended that all installations be designed to the new I.S.10101 – standard from 1 February 2020. However, whether an installation may be certified to the old standard depends on its date of design:

Summary of Key Dates:

  • 1st April 2020: New electrical installations may be designed and certified to the new standard.
  • 31st January 2021: This is the last day new electrical installations may be designed to the old standard (such installations must be certified by 31 July 2022).
  • 1st February 2021: New electrical installations must be designed to the new standard.
  • 31st July 2022: This is the last day an installation may be pre-connection certified to the old standard (such installations must have been designed by 31 January 2020).
  • 1st August 2022: Electrical installations must be certified to the new standard. If you are unsure whether the project will meet this deadline, you should design the installation to the new standard.

It is the responsibility of the REC undertaking the works to ensure they are certifying the installation to the correct standard.

Is it acceptable to perform an insulation resistance test on an installation with electronic RCBO’s and SPD connected and in the On position?

You need to ensure all appliances, lamps, LEDs, sensitive equipment & SPDs are removed and that the electronic RCBOs are in the OFF position before the test as they may be damaged by the high test voltage.


Kempston Controls is committed to finding you the ideal solution for your application. Call us today on 042 9359393, email us at electrical@kempstoncontrols.ie, or alternatively contact us here, we will be happy to help.

Kempston Controls

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