A public-access defibrillator that has been correctly sited does nothing for a bystander if its pads have expired or its status was never logged with the ambulance service. Defibrillator servicing — the ongoing cycle of checking, replacing, and reporting that follows installation — is what separates a cabinet with a machine inside it from a device an ambulance control room can actually send someone to. This piece sets out what that servicing cycle involves, and why registration on the UK’s national defibrillator network, The Circuit, is as much a part of readiness as the hardware itself.
Servicing is a separate job from siting
Deciding where a defibrillator goes — outside a community hall, at a transport hub, in a borough building — answers one question. Keeping it usable months and years later answers a different one entirely. Every AED has consumable parts: electrode pads and a battery, both with fixed shelf lives, alongside a device status indicator that reports whether the unit considers itself ready for use. None of that maintains itself. A defibrillator that was perfectly positioned on installation day can quietly become non-functional within a year if nobody owns the follow-up.
This is the gap that has driven national efforts to formalise defibrillator servicing rather than leave it to chance. It matters more in a dense urban environment like London, where a device’s usefulness depends entirely on it working in the specific minutes a 999 call is being handled, not on whether it was working when someone last happened to glance at it.
The Circuit: registering the device, not just installing it
The UK’s national defibrillator network, known as The Circuit, was developed by the British Heart Foundation in partnership with organisations including St John Ambulance, the Resuscitation Council UK, NHS England, and the Association of Ambulance Chief Executives. All UK ambulance services draw on it to locate the nearest available device during an out-of-hospital cardiac arrest and direct a 999 caller straight to it.
Being listed on The Circuit is not a one-off registration step completed at purchase. Each device has a nominated guardian — the individual or organisation responsible for it — who is expected to keep the entry current: confirming the unit is "Emergency Ready," and just as importantly, marking it as unavailable if it has been used, is faulty, or has expired consumables. A defibrillator that sits in a cabinet but was never logged, or whose status was never updated after its pads lapsed, may still be dispatched to a caller by an ambulance service that has no way of knowing otherwise. Registration and honest status reporting are what make the network trustworthy, not merely the existence of the device.
What the recurring checks actually cover
Guardianship comes with a short list of recurring tasks rather than a single annual inspection. The table below reflects the core cycle expected of anyone responsible for a public-access unit.
| Check | Typical frequency | What it confirms |
|---|---|---|
| Visual/physical check | Weekly | No visible damage, cabinet intact, accessories (razor, gloves, scissors) present, status light shows ready |
| Pad expiry | Checked at each visit; replaced before expiry | Electrode pads have not passed their use-by date |
| Battery expiry | Checked at each visit; replaced before expiry | Battery has sufficient remaining shelf life to deliver a shock if needed |
| Status reporting | Immediately after any check or use | The Circuit record reflects "Emergency Ready" or flags the device as unavailable |
None of these steps is technically difficult on its own. What makes the cycle fail in practice is drift — a reminder email that goes unread, a guardian who changes role without a handover, a pad expiry date nobody transferred to a calendar. The network itself tries to close that gap by sending email reminders ahead of expiry dates, but the underlying check still has to be carried out by a person standing in front of the cabinet.
Who actually does the checking
In practice, guardianship is split between two models. Many community organisations, residents’ associations, and small venues nominate a volunteer guardian who carries out the weekly visual check and consumable-expiry review themselves, ordering replacement pads or a battery directly when needed. Larger sites — offices, transport interchanges, larger public buildings — more often contract a maintenance provider to carry out scheduled servicing and replacement on their behalf, particularly where several devices are managed across a portfolio of sites and a single missed check could go unnoticed for longer. Neither model is inherently more reliable; what matters is that responsibility for each individual device is clearly assigned to one person or one contract, rather than assumed to be "someone’s job" in general.
Why this belongs in a readiness conversation, not just a purchasing one
Discussions about public-access defibrillators tend to concentrate on acquisition — how many units a borough or building needs, and where. That is a necessary starting point, but it is only the first half of the picture. A device’s real contribution to community resuscitation is determined by whether it is still functional and still findable on the day it is needed, which depends entirely on the unglamorous cycle of pad checks, battery checks, and accurate status reporting described above. Registering a defibrillator on The Circuit and keeping that registration honest is what turns a piece of equipment into part of London’s actual emergency response chain, rather than a fixture that happens to be present.
For anyone responsible for a public-access unit, the practical takeaway is straightforward: treat defibrillator servicing as a recurring commitment with an owner, not a box ticked once at installation, and make sure The Circuit always reflects the true state of the device.