How are security and access control systems upgraded?

A building cannot be unsecured while its security system is being replaced. That constraint shapes the entire method.

Install alongside, then cut over

The new cabling, devices, controllers and head end go in while the existing system keeps running.

Only when the new system is installed and tested does the changeover happen, and it happens in a short planned window rather than over weeks.

That means a period where both systems are physically present, which costs more in cabling and coordination and removes the gap where a facility would otherwise be exposed.

Who has to be in the conversation

**The client's security provider,** who holds the monitoring contract and the existing configuration.

**The monitoring service,** which needs to know before any alarm signal changes, or a cutover generates a false response.

**The facility's own people,** because access control decides who can get into the building tomorrow morning. A cutover that locks staff out is a failure regardless of how well the system works.

**The certifier or authority** where the system interfaces with fire, because the interface between security and [fire detection](/answers/fire-services-and-detection-upgrades) is regulated. Doors that must unlock on alarm have to unlock on alarm, before and after.

What the work usually covers

**CCTV,** including camera positions, cabling, recording and storage. Camera position is a design decision with privacy implications, particularly on a school, and it is agreed rather than chosen on site.

**Access control,** readers, locks, controllers and credentials. The credential migration is frequently the largest part of the job: every existing card or fob has to work on the new system, or every user needs a new one issued before the cutover.

**Intruder detection,** sensors, panels and the monitoring connection.

**Electronic locking,** which interacts with egress requirements. A door that locks has to still open from inside without a key.

**Intercom and entry,** where visitors are managed at a gate or a reception.

Data and privacy

CCTV on a school or a public facility records identifiable people, including children.

Where cameras point, how long footage is kept, who can access it and how it is stored are governed by the client's own policy and by law. Those are client decisions, documented before installation rather than configured by whoever commissions the system.

The contractor's role is to install what has been decided and to hand over a system the client can administer, not to make the policy.

Screening matters more here

Workers installing a security system see the layout of the security system.

Everyone on this work is screened and inducted to the same standard as any other trade on the site, which on schools and government facilities means the relevant clearances verified before access, as set out in [workforce screening and site inductions](/answers/workforce-screening-and-site-inductions).

On secure and restricted sites the client's own requirements apply on top and are usually the longer lead item.

Handover is the deliverable

As-built documentation showing every device and every cable route.

Administrator training for the people who will manage credentials daily, because a system nobody can add a user to is a system that gets propped open.

Credentials issued and tested before the old system is retired.

Configuration documented and handed over, so the client is not dependent on one contractor to make a change.

A security upgrade where the client cannot administer the result has solved a hardware problem and created an operational one.

[Discuss a security upgrade](/contact).