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NSAI wish to announce that  I.S. 420:2004 has been withdrawn and updated with the Publication of I.S. 420:2023 - Pre-cast Concrete Manholes.

This revised standard includes important updates to take account of improvements in manufacturing. In addition, it complements new codes of practices in safety for access and egress from confined space.

This standard supports the UN Sustainability Development Goal 9 in building resilient infrastructure, that promotes inclusive and sustainable industrialization, while fostering innovation.

It’s a national standard for precast Concrete manhole, the standard was revised to take account of changes in the manufacturing process as well as keep the standard up to date with code of practices for health and safety, for access into and out of the manhole.

Irish manufacturing companies certify themselves to I.S. 420.


I.S. 420:2023 does not apply to pre-cast concrete manholes of elliptical cross-section or steel fibre. This standard applies to manholes for installation in carriageways of roads (including pedestrian streets), hard shoulders and parking areas for all types of road vehicles. It also applies to units subject to lighter traffic loading. Requirements for soakaways, landing slabs and corbel slabs are also specified. This Standard does not apply to planning, design, installation, or testing of drains and sewers within the scope of I.S. EN 752, I.S. EN 1295-1 and I.S. EN 1610.