How to choose a commercial CCTV system

Most commercial CCTV problems start before anything is fitted. Someone asks for “16 cameras”, the system goes in, and the first time it’s needed the footage shows that something happened but not who did it.

A better brief starts with a different question: what does each camera need to show, and why? This guide goes through how to answer that, then how the answers set the cameras, the storage and the network. For the legal side, see our guide to CCTV and GDPR.

Start with what each camera has to show

Security professionals call this the operational requirement, and BS EN 62676-4 is the standard that covers it. In practice it’s a list, one line per view:

• Where: the vehicle gate, the loading bay, the stock cage, the cash office door
• What’s the risk: theft from the yard, staff safety, disputes over deliveries
• What must the footage do: show that someone was there, follow them across the site, or identify them to the police
• When: all day, or only after dark when the site is empty

That list is also the start of your DPIA, because the ICO expects you to be able to explain why each camera is there. It may also show that a camera isn’t the answer. The ICO suggests considering less intrusive options, and sometimes better lighting or a stronger fence meets the need.

How much detail: pixels per metre

Resolution on its own doesn’t tell you much. What matters is how many pixels land on the subject, measured in pixels per metre (px/m) across the scene. The 2014 edition of the international standard behind BS EN 62676-4 gives these guideline figures:

To see what that means for a camera, divide its horizontal pixels by the figure you need. The result is how wide a scene it can cover at that level:

So a single 4MP camera covering a 40m yard can show that people are there and what they’re wearing, but it won’t identify them. To get a face you need a second, narrower camera at the point everyone has to pass, usually the gate or the door.

Treat these as starting points. They’re guidelines for human viewers, and low light, poor lenses and heavy compression all reduce what you really get. The 2025 edition of the standard uses new category names and more levels, so check which one your specification refers to. Thermal cameras and video analytics work to different measures.

Which cameras go where

A PTZ camera only sees where it’s pointing, so it records nothing useful elsewhere while someone zooms in. It’s a good addition to fixed cameras but a poor replacement for them.

Light decides a lot. A camera that works at noon can be useless at midnight, so look at each view after dark before you settle the design. Poorly lit yards and fence lines are where thermal and low-light cameras earn their place.

Recording, storage and finding footage

Footage is recorded on a network video recorder or a server running video management software. We install HikCentral Professional and Luxriot EVO, which scale from one site to many.

Storage follows from the bitrate, the number of cameras and your retention period. As a worked example, one camera recording continuously at 4 Mbps uses:

• per day: 4 Mbps × 86,400 seconds ÷ 8 = about 43GB
• over 30 days: about 1.3TB
• 16 cameras over 30 days: about 21TB

Higher resolutions and busy scenes push the bitrate up, while modern compression and motion-based recording bring it down. Ask for the sum, using the settings the system will really run at. Our guide to how long to keep CCTV footage covers how to set the retention period.

Look beyond specifications at how you’ll use the system on a bad day. The ICO points to practical features such as audit trails, finding footage for an access request, and redacting other people. Check how quickly someone can find a clip by time and camera, export it with the date and time intact, and show who has viewed it.

The network and your IT team

IP cameras are computers on a network, and your IT team should treat them that way. We design for the review from the start:

• segregated VLANs where your IT team provides them
• no direct internet access from cameras or servers
• encrypted site-to-site VPNs on multi-site systems
• default credentials removed and devices hardened
• TLS throughout and full audit logging
• permissions set by role, so people only see the cameras they should

Remote viewing on desktop and mobile works within those rules. Ask any installer how they deliver it, because opening ports to the internet is the weak point.

Upgrading an analogue system

You may not have to replace everything at once. Cameras of a recent enough standard can stay and work alongside new IP cameras, and the rest can be replaced in phases to suit a budget. A survey is the only way to tell which is which, especially if nobody has records of the camera positions or cable routes.

Keeping it working

A camera that failed last month and a recorder that stopped writing footage look fine until you need them. Plan for that when you buy the system. Our maintenance contracts offer service levels of four hours for a critical system outage, one to two business days for a camera failure and two to four business days for minor faults, confirmed in the contract.

What to ask a CCTV installer

• What will each camera show, and at what level of detail? Can I see that in writing?
• How did you size the storage for my retention period?
• How does the system sit on our network, and will it pass our IT review?
• How do we find and export footage, and who can do it?
• Which existing cameras and cabling can stay?
• What does the handover include: training, drawings and passwords?
• What’s the warranty, and what does maintenance cover?
• Will you help with the technical details for our DPIA and our CCTV signs?

Planning a new system, or replacing one that doesn’t show what you need? The survey is free, and we start with what you need to see. See our commercial CCTV service, or tell us about your site.