Low-voltage electrical installations - Part 5-56: Selection and erection of electrical equipment - Safety services

Overview

IEC 60364-5-56 sets general requirements for the selection and erection of supply systems and electrical safety sources for safety services, for example fire-fighting equipment and emergency lighting. Its aim is for safety services to keep working during and after a fire. In a data centre, loads such as fire pumps, smoke extraction and emergency lighting therefore fall under this standard.

An important boundary is that standby electrical supply systems are outside the scope. The standard also does not apply to hazardous areas (BE3), which are covered by IEC 60079-14. The distinction matters for understanding that a data centre's IT standby generators count as standby sources, not safety sources; the two concepts are tied to different sets of requirements.

Among the third edition's additions are circuit and overcurrent protection requirements to maintain safety-service supplies under fire conditions. It also stipulates that safety-service circuits are not to be protected by residual current devices (RCDs) or arc fault detection devices (AFDDs). The intent is to avoid the circuit dropping out unnecessarily during a fire.

The document is Edition 3, published on 2 November 2018. It has 62 pages and replaces the 2009 edition. The record rests only on the IEC webstore abstract, so the full text should be consulted for detailed wiring and protection rules. Related documents named are IEC 60364-1, NFPA 110 and the Turkish regulation on fire protection of buildings.

Key points

1. Sets general requirements for safety services and the selection and erection of their supply systems and safety sources.
2. Standby electrical supply systems are outside the scope.
3. Does not apply to hazardous areas (BE3), covered by IEC 60079-14.
4. Adds circuit and overcurrent protection requirements to maintain safety-service supplies under fire conditions.
5. Circuits for safety services are not to be protected by RCDs or AFDDs.
6. Edition 3 was published on 2 November 2018 (62 pages) and replaces the 2009 edition.

Using it in design

• In source modelling, keep safety-service loads (fire pumps, smoke extract, emergency lighting) on a separate bus fed by a qualified safety source.
• Use fire-resistant cabling on these circuits and apply no RCD/AFDD protection.
• Label the data centre's IT standby generators in the tool as standby sources, not safety sources.
• Cross-check against local rules such as the Turkish regulation on fire protection of buildings.

Who should read it

Electrical designers, fire-safety engineers and consultants setting the supply architecture of a data centre.

Related standards

• IEC 60364-1
• NFPA 110
• Binaların Yangından Korunması Hakkında Yönetmelik

Publication details

Authors

IEC TC 64

Publisher

IEC

Year

2018

Document number

IEC 60364-5-56:2018

Document language

English

Source type

Standard

Access

Citation only

Licence

Copyright retained; citation only — the publisher’s terms apply to the original document

Citation