Commercial security installer SSAIB vs NSI — what is the difference?

SSAIB (Security Systems and Alarms Inspection Board) and NSI (National Security Inspectorate) are the two main UK accreditation bodies for commercial security installers. Both audit installers against industry codes of practice (BS EN 50131 for intruder, BS 8418 for monitored CCTV, BS 7858 for staff vetting) and publish public member registers. Many commercial insurance policies reference accreditation from either body as an acceptable standard. Police forces accept URN allocation from accredited installers under either scheme. Both are credible. The right choice for any installer typically comes down to local industry relationships and audit cycle preferences.

How to verify any installer's accreditation claim

Both bodies publish searchable member registers on their public websites — SSAIB at ssaib.org, NSI at nsi.org.uk. Membership is verifiable in seconds. If an installer claims accreditation, the public register confirms or denies it. Always verify before signing a commercial contract.

Flextec's position on accreditation

Flextec Limited operates to BS EN 50131, BS 8418, BS 5839-1, BS 7273-4 and ICO surveillance code in every install. Industry body accreditation sits on the 2026 roadmap — track our progress on the 2026 Buyer's Guide.

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By Sam Davis, Founder — 40+ years combined Yorkshire commercial security experience. Read more about Sam.