Security grades · Order INT/316/2011 · EN 50131
Security grades 1 to 4. What each one requires and who decides.
The grade states the risk, and the intruder, that an alarm system is designed for. In Spain, Order INT/316/2011 assigns it by type of installation, and EN 50131 turns it into requirements for every component. S3 designs the system to the required grade; the licensed security company you choose installs, connects and certifies it.
What a grade is
It does not measure the quality of the equipment. It measures who the system has to withstand.
Four levels of risk
EN 50131-1 sets four grades, from 1 (low risk) to 4 (high risk), each assuming an intruder with more knowledge and resources. Order INT/316/2011 assigns them according to the premises and to whether the system must be connected to an alarm receiving centre (ARC).
The whole system achieves it
A subsystem takes the grade of its lowest component, and the system that of its lowest subsystem (art. 3.4). Each component proves its grade with a conformity assessment by an accredited body (art. 3.1), not with a datasheet.
The four grades
The Order assigns the grade by type of installation. EN 50131-1 describes it by the intruder.
| Grade | Risk | Applies to | Reference intruder |
|---|---|---|---|
| 1 | Low | Systems with audible warning that will not be connected to an ARC. | Intruder with little knowledge and common tools. |
| 2 | Low to medium | Homes and small premises, shops and industrial sites in general that intend to connect to an ARC. | Intruder with limited knowledge, general tools and portable instruments. |
| 3 | Medium to high | Establishments obliged to have security measures, and other commercial or industrial installations required to connect to an ARC. | Intruder conversant with alarm systems, with tools and portable electronic equipment. |
| 4 | High | Critical infrastructure, military installations, premises storing regulated explosives, and security companies that hold cash, valuables, precious metals, hazardous materials or explosives, whether or not connected to an ARC. | Intruder who plans in detail and can substitute components. |
Summary of article 2 of Spain's Order INT/316/2011 and of the grade definitions in EN 50131-1. It does not replace the official text.
What changes in the design as the grade rises
The detailed requirements are in EN 50131 and its parts. These are the ones that change the design most.
Anti-masking
At Grades 3 and 4, movement detectors must signal masking attempts: covering, spraying or blinding their optics. The design defines how that signal is handled and who receives it.
Supervision and tamper
The system signals a cut cable, a detector that stops reporting or radio interference. As the grade rises, supervision of interconnections and tamper detection become stricter: opening of the housing and, depending on the component, removal from its mounting.
Transmission and paths
EN 50131-1 links each grade to notification options using single-path or dual-path transmission systems, classified under EN 50136. The higher the grade, the more demanding the categories: the path is checked more often and its failure is reported sooner. In some cases, such as bank strongrooms, Order INT/317/2011 requires two separate communication paths.
Power and standby time
The standby time required depends on the grade and on whether mains failure is reported to the ARC. The load and standby calculation is set out in the calculation annex of the technical report.
Protecting the control panel and cabling
The design places the control panel, power supplies and junction boxes inside the protected area, with tamper detection, and routes cabling along protected paths.
Tests that prove it
Each requirement becomes an acceptance test: mask a detector, cut a path, remove mains power. If it cannot be checked on site, it is not properly specified.
Video and access control have their own scale
The Order assigns grades to alarm systems. Video and access control are graded under their own standards.
Video surveillance: EN 62676
Four grades, set by the risk assessment and applied to functions such as recording, logs or tamper detection rather than to each camera.
Access control: EN 60839-11-1
Four grades, assigned to each access point. A plant room and the visitor entrance need not share a grade.
Video that verifies alarms
If the ARC verifies alarms by video, camera coverage must be equal to or greater than that of the associated detector (Order INT/316/2011, art. 8). The design places detectors and cameras together.
Who decides the grade
The regulation sets the minimum grade. The risk analysis decides where to reinforce.
The regulation sets the minimum
Establishments that the Private Security Regulations oblige to have an intrusion system connected to an ARC must meet Grade 3 (Order INT/316/2011, art. 3.2). Order INT/317/2011 sets the measures for credit institutions, jewellers and other obliged establishments. The competent authority may change the grade assigned (art. 3.3).
The insurer may ask for more
The policy may require a grade, connection to an ARC, or both. That is a condition of the contract, not of the regulation.
The risk analysis decides where to reinforce
The preamble to the Order asks designers to take into account the nature of the premises, the value of the contents and the expected intruder profile. The analysis applies that criterion zone by zone; the owner, who accepts the residual risk, decides on that basis.
Grade 4 and critical operators
The Order reserves it for critical infrastructure and other high-risk installations, whether or not connected to an ARC.
An intruder who plans
The design assumes a well-resourced adversary, able to study the system and substitute components. Transmission, protection of the control panel and resistance to substitution come to the fore.
With the security manager
For critical operators, the design is drafted with the organisation's security manager and starts from its security planning. S3 turns those plans into verifiable requirements and acceptance criteria.
Typical failures we design out
- Typical failure
- Grade 3 detectors on a Grade 2 control panel or transmitter. The system stays at Grade 2.
- In the design
- We set the grade of every component and subsystem, and the specification requires the certificate for each product.
- Typical failure
- Raising the whole installation to Grade 3 because one area needs it, or leaving it at Grade 2 because most of it does not.
- In the design
- Clearly bounded subsystems, each with its own grade, and shared equipment sized for the most demanding one.
- Typical failure
- Asking for “Grade 3” in the tender without saying for which subsystem or with what transmission. Each installer reads it differently.
- In the design
- The specification turns the grade into requirements that are checked in the acceptance tests.
What you receive
- Risk analysis
- Grade justified per subsystem
- Specification with grade requirements
- Acceptance test protocol
- Grade compliance plan
- Designs S3
- Installs, connects and certifies the licensed security company you choose
- Operates your team
Reference standards
- Order INT/316/2011 Alarm systems: grades, design and servicing.
- Order INT/317/2011 Measures for obliged establishments.
- Law 5/2014 Private security: who installs and connects.
- EN 50131-1 Intrusion and hold-up: requirements and grades.
- CLC/TS 50131-7 Application guidelines; the installation design is drawn up in line with them.
- EN 50136 Alarm transmission and its categories.
- EN 62676 Video surveillance: grades by function.
- EN 60839-11-1 Access control: grade per access point.
Questions
Who decides the grade?
The regulation sets the minimum according to the type of establishment, and the competent authority may change it. The insurer may require more. Above the minimum, the risk analysis shows which areas to reinforce, and the owner decides on that basis.
Can the insurer require a grade?
Yes. The policy may make cover conditional on a grade, on connection to an alarm receiving centre, or on both. That is a condition of the contract, not of the regulation. It is worth having the exact wording of the clause before the design starts; interpreting it is a matter for the insurer or the broker.
Does Grade 3 require connection to an ARC?
Not by itself. The obligation comes from the regulations that apply to the establishment or from the insurance contract. Order INT/316/2011 assigns Grade 3 to obliged establishments and to installations required to connect. If the system is connected to an alarm receiving centre (ARC), a licensed security company installs, connects and certifies it, and you contract the service with that company. S3 designs the transmission; it does not provide it.
Can part of the installation have a higher grade?
Yes. Order INT/316/2011 allows clearly defined subsystems with different grades. Each subsystem takes the grade of its lowest component. Shared components, such as the control panel, the power supply or the transmission equipment, must match the grade of the highest subsystem. The design marks those boundaries on the drawings.
Asked for a grade and not sure what to specify?
Tell us about the installation and who is asking for the grade. The first conversation lasts 30 minutes, is with an engineer and is free of charge.