New Irish Standards: The Basics of Surge Protection – Phoenix Contact

FIGURE 9.54: Multi-stage protection scheme in accordance to IEC lightning protection standards (see IEC 60364-5-53)

More and more sensitive electronic equipment is being used every day in Ireland. Electronic devices get smaller and smaller and, while saving space is beneficial, sometimes it has its drawbacks. The smaller the electronics get, the more difficult it is to protect electronic devices against man-made surges and lightning-induced surges. The new Irish standard 10101-2020 reflect this change with a complete review on the sections affecting surge protection.

What has changed for surge protection? 

Under the new rules, I.S. 10101-2020, the following sections received a major overhaul:

FIGURE 9.55: Pluggable Type 1 SPD with three L/N spark gaps and one N/PE spark gap; for the diversion of high-energy lighting currents (10/350 µs); four modes of protection; suitable for the protection of three-phase five-wire system.
  • Part 443 – Protection against transient over voltages of atmospheric origin or due to switching. This section details how you determine whether a surge protective device (SPD) is required for your installation with details of a risk assessment method. It is always a good idea to install an SPD and so you could negate the need to carry out your risk assessment by simply installing surge protection as a standard at the origin of the installation.
  • Part 534 – Devices for protection against over voltages. This section goes into detail about surge protection selection and erection and insulation coordination. It gives clear guidelines as to what type of surge protection is required in your installation and also, more importantly, how to install them correctly.
  • Part 712 – Photovoltaic systems. This section describes how to protect your PV system in both domestic and commercial applications. This includes protection on both the AC side and the DC side. 

How do we protect against Surges?

Surge-protective devices (SPDs) can consist of:

  • Voltage-switching components: spark gaps, gas-discharge tubes (GDTs)
  • Voltage-limiting components: metal-oxide varistors (MOVs), suppressor diodes
  • Combinations of voltage-switching and voltage-limiting components

FIGURE 9.56: Pluggable Type 2 SPD with three varistors (between L and N) and one gas-discharge tube (between N and PE); for the diversion of surge currents (8/20 µs); four modes of protection; suitable for the protection of three-phase five-wire systems.

The I.S. 10101-2020 stipulates to use different types of SPDs at certain installation locations. For the protection of power systems, three types/classes of SPDs (Class I / Type 1, Class II / Type 2, Class III / Type 3) are defined in IEC 62305-4 and IEC 61643-11. 

Type 1 [T1] / Class I SPDs Usually installed in facilities with external lightning protection system or facilities supplied by overhead lines. The typical installation location for this kind of SPDs is the service entrance or the main distribution cabinet. An installation in close proximity to the main earthing busbar is recommended. Type 1 SPDs have a high discharge capacity (lightning current impulse Iimp [10/350 µs], surge-current impulse In [8/20 µs]). Typical surge-protective components used in Type 1 SPDs are spark gaps, big varistors and big GDTs.

Type 2 [T2] / Class 2 SPDs The typical installation locations for this kind of SPDs are the main distribution cabinet (of facilities supplied by buried cables and without external lightning protection system) or sub-distribution cabinets. Type 2 SPDs have a medium-high discharge capacity (surge-current impulse In [8/20 µs]). Typical surge-protective components used in Type 2 SPDs are medium-sized varistors and medium-sized GDTs. 

FIGURE 9.57: Pluggable Type 3 SPDs; left: suitable for single-phase three-wire systems; right: suitable for three-phase five-wire systems.

Type 3 [T3] / Class 3 SPDs The typical installation location for this kind of SPDs is a location close to sensitive equipment. Type 3 SPDs have a relatively low discharge capacity (combination wave impulse, 1.2/50 µs, 8/20 µs, 2 ohm, UOC). Typical surge-protective components used in Type 3 SPDs are small varistors, small GDTs and sometimes suppressor diodes.

Why use Phoenix Contact surge protection devices… 

Phoenix Contact are the world leaders and innovators in Surge Protection research and development. We continually innovate our product portfolio to meet the demand of our industry partners. Phoenix Contacts range of SPD cater to all applications for domestic and industrial installations and for the power supply, telephone systems, instrumentation, control and data communication.

FIGURE 9.58: Phoenix Contacts CHECKMASTER 2, a fully automatic high-voltage test device for the touch-safe electrical testing of pluggable SPDs.

Testing and maintenance 

In IEC 62305-3 and IEC 62305-4, it’s stipulated that lightning protection systems shall be inspected periodically. During a visual inspection, it is not possible to assess the status of an SPD properly. A proper assessment is only possible by carrying out measurements in accordance with the manufacturer’s instructions. To be able to test SPDs comfortably and in a safe way, it is recommended to use pluggable SPDs. A high-voltage test device is needed for the proper testing of SPDs.

Further information

To get a free copy of “Lightning and surge protection basics” please email 

For advice on your project or application please contact our office on 01 205 1300