The short answer
You only need an NSI or SSAIB approved installer when you want a verified police response or your insurer requires a certificated system — for a basic deterrent alarm it is optional but reassuring. NSI (National Security Inspectorate) and SSAIB (Security Systems and Alarms Inspection Board) are the two main UKAS-backed certification bodies for security installers in the UK. Their approval shows a company has been independently inspected and works to recognised standards such as EN 50131. Police forces will only register a system for a Unique Reference Number (URN), and therefore police response, if it is installed and maintained by an approved company. Many insurers that require a graded alarm also require approved installation. If you want neither police response nor a certificated insurer-compliant system, an approved installer is a quality marker rather than a strict requirement.
The need for approval depends on what you want the alarm to achieve. The sections below explain what the two bodies are, when approval is mandatory in practice, and when a non-approved installer is fine.
NSI & SSAIB
- NSINational Security Inspectorate
- SSAIBSecurity Systems and Alarms Inspection Board
- BasisUKAS-backed, EN 50131 standards
- Needed for police URNYes
- Needed for some insurersOften, for graded systems
What NSI and SSAIB approval means
NSI and SSAIB are the two principal certification bodies for security and fire installers in the UK. Both are recognised by UKAS (the national accreditation body) and by the police and insurance industry. When a company is approved, it has been independently audited and shown to install and maintain systems to recognised standards, including EN 50131 for intruder alarms, and to operate proper procedures for design, installation, maintenance and record-keeping.
Approval is not a single tier — NSI offers levels such as NSI Gold and Silver, and SSAIB has its own scopes — but the practical point is the same: an approved company has third-party oversight, whereas a non-approved installer is self-certifying. That oversight is exactly what the police and many insurers rely on, which is why approval becomes a requirement in specific situations rather than always.
When you genuinely need an approved installer
There are two situations where approval is, in practice, required. First, police response: UK police forces only issue a Unique Reference Number (URN), and therefore only provide a response to a monitored alarm, if the system is installed and maintained by an NSI or SSAIB approved company and meets the confirmation requirements that reduce false calls. Without an approved installer there is no route to a verified police response.
Second, insurance: where a policy specifies an alarm — often for higher-value contents — it commonly requires the system to be of a stated EN 50131 grade and to be installed and maintained by an approved company, with a certificate to prove it. Fitting a system through a non-approved installer in that case can leave a theft claim exposed. The table summarises when approval matters.
| You want... | Approved installer needed? |
|---|---|
| Police-response monitoring (URN) | Yes |
| Insurer-specified graded alarm | Often yes |
| Certificated, maintained system | Yes |
| Basic bells-only deterrent | No (optional) |
| Self-install smart alarm | No |
When NSI/SSAIB approval is required versus optional, in practice.
When approval is optional
If you simply want a deterrent alarm — a visible siren and working sensors — and you do not need police response or an insurer-certificated system, you do not strictly need an NSI or SSAIB installer. A competent non-approved installer, or a self-install smart kit, can give effective deterrence and detection. Approval in this case is a quality reassurance rather than a legal or contractual requirement.
The sensible approach is to decide what you want first: if the answer includes verified police response or insurer compliance, use an approved company and ask to see the certification (you can verify a company on the NSI or SSAIB website). If you only want a deterrent and self-monitoring, prioritise a reputable installer and good kit, and treat approval as a bonus. Either way, confirm any insurance requirement in writing before committing, because the cost of getting it wrong is a rejected claim, not just a different install.
What an approved installation actually involves
Approval is not just a logo — it reflects a defined process. An NSI or SSAIB approved company designing an intruder alarm typically carries out a risk assessment and survey of the property, produces a system design and specification, installs to the relevant EN 50131 grade, commissions and tests the system, and issues documentation including a certificate. For monitored systems they arrange the connection to an Alarm Receiving Centre and, where police response is required, the registration that produces the URN. They are also bound to provide ongoing maintenance, with the standard generally expecting at least one inspection per year for a graded system, and more frequent attention for higher grades or remotely-signalled systems.
That paper trail and maintenance regime are precisely what insurers and the police rely on. A certificate of installation and a current maintenance contract are the evidence a claims handler looks for, and the maintenance visits keep the system verified rather than quietly degrading. A non-approved install can be perfectly competent, but it does not come with this independently-audited framework — which is why, when certification or response matters, the approval is the point rather than an optional extra. When choosing a company, check the certification body's register, confirm the scope covers intruder alarms to the grade you need, and ask to see the install certificate and maintenance terms before work begins. It is also worth confirming how the company handles call-outs and faults between scheduled visits, since a system that is certificated but slow to repair can still lapse from the standard your insurer or police registration relies on. A reputable approved installer will set out the response times and what the maintenance contract covers in writing.
Frequently asked questions
Is it illegal to fit an alarm without an approved installer?
No. There is no law requiring an NSI or SSAIB installer for a domestic alarm. Approval becomes necessary only when you want a police-response URN or your insurer specifies a certificated, approved-installed system. For a basic deterrent alarm, approval is optional.
How do I check if an installer is NSI or SSAIB approved?
Both bodies publish searchable registers of approved companies on their websites, so you can verify a firm's certification and scope directly. Ask the installer for their certificate and check it against the register rather than taking the claim at face value.
What is the difference between NSI and SSAIB?
They are two separate UKAS-recognised certification bodies that do broadly the same job — independently inspecting and certifying security installers to recognised standards. Police and insurers accept both. The practical difference for a homeowner is minimal; what matters is that the installer holds valid approval from one of them.
Sources & further reading
- NSI — National Security Inspectorate (find an approved company)
- SSAIB — Security Systems and Alarms Inspection Board
Figures on this page are typical UK ranges drawn from published sources and depend on your specific property and system. They are guidance, not a quotation.