Quick reference · CCTV: application guidelines
How to design and check a CCTV system against what it is for: the operational requirement, how much detail each camera must capture, lighting, storage and evidence.
How to plan a CCTV system around what each camera has to do, and how to check that the picture is detailed enough.
BS EN IEC 62676-4:2025. BS EN IEC 62676-4:2025 (November 2025) replaced BS EN 62676-4:2015, which is superseded but still current for now.
Confirmed two or more sources agree, or a source quotes the standard. Check one source, or a detail that could not be confirmed. Check it against the standard.
Seven levels, as minimums in pixels per metre: Overview 20, Outline 40, Discern 80, Perceive 125, Characterise 250, Validate 500 and Scrutinise 1500. They replaced the older Detect, Observe, Recognise and Identify names.
There are seven levels of detail, from Overview (20 pixels per metre) up to Scrutinise (1500). Each one is a minimum.
In the 2015 edition: Monitor 12.5, Detect 25, Observe 62.5, Recognise 125, Identify 250 and Inspect 1000 pixels per metre. Perceive (125) and Characterise (250) match Recognise and Identify in number.
The older editions used Monitor, Detect, Observe, Recognise, Identify and Inspect. Recognise and Identify are the same numbers as Perceive and Characterise now.
The standard defines it as the pixels at the target per unit length. In practice it is the camera's horizontal resolution divided by the width of the scene at the target, in pixels per metre.
Divide the number of pixels across the picture by how many metres wide the scene is at the target.
Field of view = 2 × atan(sensor width ÷ (2 × focal length)). Scene width at a distance = distance × sensor width ÷ focal length. Many CCTV sensors are wider than they are tall, so use the sensor size from the data sheet.
A shorter lens sees wider. Divide the sensor width by the focal length to see how wide the scene is at each metre of distance.
BSI lists BS EN 62676-4:2015 as superseded but still current, replaced by BS EN IEC 62676-4:2025. The date the older edition is withdrawn is not confirmed.
The 2015 edition has been replaced but can still be used for now. The date it stops is not confirmed.
There is no legal minimum or maximum. The ICO and the Surveillance Camera Code of Practice (principle 6) both say to keep footage no longer than you need for your stated purpose, and to write the period in your CCTV policy.
The law sets no fixed time. Keep it only as long as you need it for the reason you record, and put the period in your policy.
Gigabytes per day per camera = megabits per second × 3600 × hours ÷ 8 ÷ 1000, in decimal units. Multiply by cameras and days kept, and allow for overhead. Some recorder software counts in binary units, which shows about 7% less per gigabyte.
Work out how much each camera records per day from its bitrate, then multiply by the number of cameras and the days kept.
At the switch port and at the device: 802.3af 15.4 W and 12.95 W, 802.3at 30 W and 25.5 W, 802.3bt Type 3 60 W and 51 W, Type 4 90 W and 71.3 W. Cable runs are limited to 100 m.
The switch supplies a bit more than the camera receives, because some is lost in the cable. Keep cable runs under 100 m.
A security concept covering structural, electronic and organisational measures, built from a risk assessment. It also adds competence tiers, security grading guidance and maintenance checklists.
The 2025 edition wants a wider plan for security, based on a risk assessment, with guidance on skills, grading and maintenance.
Start with the operational requirement (the objectives, areas and activities to capture), then camera positions and pixel density, then lighting, then storage and retention, then export. Test plans define the image quality needed for live, recorded and exported views.
First decide what each camera is for. Then place the cameras, check the light, plan the storage and how footage is exported, and test the pictures.
No. It is a simplification. Lighting, the lens, compression, distance and the display all change what you can actually make out.
Pixels per metre is only a guide. Bad light, heavy compression or a poor screen can still spoil the picture.
Nothing in this guide matches. Search all the guides.
Other guides: BS 5839-1, BS 5839-6, BS 5266-1 and BS EN 1838, BS 5306 (extinguishers), BS EN 50131-1 and PD 6662, BS 8418, BS EN 60839-11-1, BS 7273-4, BS 7671 (for alarm and CCTV work). Not sure what a word means? Explain this text or see the glossary.
For guidance only. Always check against the current edition of the standard and the manufacturer's data.
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