What is an OB book?
An OB book (occurrence book) is the bound, page-numbered register kept at a security post. The officer on duty uses it to record, in time order, everything that happens on the shift: coming on and going off duty, patrols, visitors, incidents, alarms, keys and handovers. It is the site's written record of what happened, when, and who recorded it.
In South African security, "OB" nearly always means this site register. Police stations keep an occurrence book too: when SAPS records a report that is not opened as a criminal case, it can give you an OB number for that entry, while criminal cases get a CAS number.
This guide covers the site OB. If you are deciding between a paper book and a digital one, read Digital vs Paper Occurrence Books.
What the OB is used for
A well-kept OB does four jobs at once:
- Handover between shifts. The incoming officer reads the OB to learn what is still open: a faulty gate, a contractor still on site, a missing key.
- Evidence. Entries can support a disciplinary hearing, an insurance claim or a criminal case, so how an entry is written matters as much as what it says.
- Proof of service. The client can see that the post was manned and the patrols were done, and at what times.
- Supervision and inspections. Supervisors sign the OB on site visits, and inspectors and auditors can ask to see it.
Most guarding contracts require an OB at every post, and many say what must go in it, such as officers booking on and off duty. Your contract and site instructions set the minimum for that site, so check them first.
What every OB entry must include
Every entry should let someone who was not there understand what happened without asking you. These six parts make that possible.
| Part | What to write | Example |
|---|---|---|
| Time | When it happened, on the 24-hour clock | 13:05 |
| Date | At the top of every page, and again after midnight | Friday 17/10/2026 |
| What happened | Who, what and where, in the order it happened | Storeroom door at Block C found forced open, lock broken |
| Action taken | What you did and who you told, with times | Area secured. Supervisor informed by radio at 13:07 |
| References | Any number that links the entry to another record | Incident report IR-0231, alarm company reference, SAPS CAS number |
| Your details | Name and signature, plus your PSIRA number if your company asks for it | S. Dlamini (signed) |
How to write an OB entry: 8 rules
1. Write it at the time
Record events as they happen, or as soon as you safely can. If you write later, mark it as a late entry and give both the time of the event and the time you wrote it.
2. Use the 24-hour clock
Write 13:05, not 1:05. There is no a.m. or p.m. to confuse at handover.
3. Use a pen
Black or blue ink, never pencil, so an entry cannot be rubbed out.
4. Stick to facts
Write what you saw, heard and did. Put people's exact words in quotation marks. Leave out opinions such as "he looked suspicious" and describe what the person did instead.
5. Never erase or remove anything
No correction fluid, no torn-out pages, no writing over words. Strike one line through a mistake so it can still be read, write the correction next to it and initial it.
6. Leave no gaps
Start each entry on the next line. At the end of your shift, draw a line under your last entry and sign off, so nothing can be added later.
7. Be specific
Names, vehicle registrations, unit numbers, gate and checkpoint numbers, and descriptions of people and property.
8. Keep the book at the post
The OB stays on site, where the next shift can read it. Never take it home or leave it where visitors can write in it.
OB entry examples
The entries below show a day shift at a residential complex, then an alarm on the night shift. Names, vehicle registrations and reference numbers are made up.
| Time | Entry | Signed |
|---|---|---|
| 06:00 | ON DUTY. Took over Main Gate from T. Mokoena (night shift). Received: OB, radio no. 2, torch, keys for pump room and clubhouse. Handover: gate motor faulty since 03:40, gate opened by hand. All else in order.Signed: S. Dlamini | S. Dlamini |
| 06:05 | Handed over to S. Dlamini as above. OFF DUTY.Signed: T. Mokoena | T. Mokoena |
| 07:15 | Patrol: perimeter fence and Blocks A–D. 8 of 8 checkpoints scanned. Fence intact, pool gate locked. All in order.Signed: S. Dlamini | S. Dlamini |
| 09:20 | Contractor J. Smith, ABC Plumbing, ID checked, vehicle CA 123-456, to Unit 14 (owner L. Pillay confirmed by phone). Visitor slip 0452 issued.Signed: S. Dlamini | S. Dlamini |
| 10:45 | J. Smith (09:20 entry) left site. Slip 0452 returned.Signed: S. Dlamini | S. Dlamini |
| 13:05 | Patrol: found storeroom door at Block C forced open, lock broken. Did not enter. Area secured. Supervisor P. Naidoo informed by radio at 13:07.Signed: S. Dlamini | S. Dlamini |
| 13:25 | Supervisor P. Naidoo on site and inspected Block C storeroom with me. Owner K. Botha (Unit 9) informed at 13:30 and reports 2 power tools missing. SAPS called at 13:35.Signed: S. Dlamini | S. Dlamini |
| 14:10 | SAPS Const. N. Zulu on site. Statement taken from K. Botha. CAS number recorded on incident report IR-0231.Signed: S. Dlamini | S. Dlamini |
| 16:40 | LATE ENTRY for 15:10: gate motor repaired by technician R. Khumalo. Gate working on remote. Entry late because I was escorting a delivery at 15:10.Signed: S. Dlamini | S. Dlamini |
| 17:55 | Supervisor visit. OB checked, entries 06:00 to 16:40 read.Signed: P. Naidoo (supervisor) | P. Naidoo (supervisor) |
| 18:00 | Handed over to M. Sithole (night shift). Open item: Block C storeroom (IR-0231) taped off, owner to arrange a new lock. Keys and equipment as received. OFF DUTY.Signed: S. Dlamini | S. Dlamini |
| Time | Entry | Signed |
|---|---|---|
| 02:14 | Alarm: zone 3, clubhouse back door. Armed response called at 02:15 (ref. 7781).Signed: M. Sithole | M. Sithole |
| 02:27 | Armed response on site. Checked clubhouse with the response officer: back door closed and locked, no sign of entry. Alarm reset at 02:35. Cause not found. Reported to the estate manager by message at 02:40.Signed: M. Sithole | M. Sithole |
Each entry says who, what, where, when and what was done. The Block C break-in can be followed from discovery to the SAPS case number without reading anything else, and the night shift knows from the 18:00 handover exactly what is still open.
Common OB mistakes
- "All in order" all night with no detail. Say what you checked. "8 of 8 checkpoints scanned" proves more than "patrol done".
- Writing the whole shift at the end. Entries written in one go are often wrong and easy to challenge.
- Leaving out the action taken. "Alarm went off", without who was called and what was found, leaves the next shift guessing.
- Opinions and guesses. Write what you found, not who you think did it.
- Torn-out or blank pages. One missing page makes the whole book look unreliable, including the honest entries.
- Writing for someone else. Each officer writes and signs their own entries.
For supervisors: checking the OB
- Read and sign the OB on every site visit, with the time.
- Check that the pages are numbered, none are missing, and every shift booked on and off.
- Follow up the open items in each handover entry.
- When a book is full, close it with a dated note and store it securely for as long as your contract and legal adviser require. Many security companies keep OBs for at least three years.
Paper OB or digital OB?
A paper OB works when it is kept well, but it has limits. Nobody off site can read it, a late entry looks the same as one written at the time, and you cannot attach a photo of the broken lock.
A digital occurrence book timestamps each entry when it is made and can attach photos, video, audio notes and signatures, tagged with the GPS position. Worxit's Occurrence Logs module does this on the officer's phone, and supervisors see entries as they are made. For a full comparison, read Digital vs Paper Occurrence Books.
Frequently asked questions
What does OB stand for in security?
OB stands for occurrence book: the register kept at a security post where the officer on duty records everything that happens on the shift, in time order.
What is an OB number?
On site, it is the entry or page number in the occurrence book. At a police station, an OB number is the reference SAPS gives when a report is recorded in the station's occurrence book. Criminal cases are given a CAS number instead.
What should I write in the OB when nothing happens?
Still record what you did: each patrol with its time and the checkpoints covered, checks of doors, lights and equipment, and the handover. "02:00 patrol, 8 of 8 checkpoints, all in order" shows the site was checked. A blank page shows nothing.
Can I correct a mistake in the OB?
Yes, but never erase it. Draw a single line through the mistake so it can still be read, write the correct words next to it and initial the change. Never use correction fluid or tear out a page.
Is the OB a legal document?
It is a record that can be used as evidence, for example in a disciplinary hearing, an insurance claim or a criminal case. That is why entries must be made on time, stick to facts, be written in pen and never be removed.
How long should an OB be kept?
For as long as your client contract, insurer and legal adviser require. Many security companies keep full OBs for at least three years.
Who is allowed to write in the OB?
The officer on duty writes and signs their own entries. Supervisors sign when they check the book. Nobody should write an entry for someone else.
Replace the paper OB
See how Worxit records OB entries with the time, GPS position and photos, so every entry can be trusted and every supervisor can read it from anywhere.