On site
What is a permit to work?
A permit to work is a formal written authorisation to carry out a defined high-risk task, issued for a set time and set conditions, and signed back when the work is complete.
Use this diagram+
Free to use on your own site, in training material or in a handout, as long as the credit link stays on it. Paste this where you want the diagram to appear.
<figure>
<img src="https://buildoptix.co.uk/glossary/permit-to-work/diagram.svg" alt="permit to work — diagram from BuildOptix" width="880" height="620" loading="lazy">
<figcaption>
<a href="https://buildoptix.co.uk/glossary/permit-to-work">What is a permit to work?</a> — diagram by
<a href="https://buildoptix.co.uk">BuildOptix</a>
</figcaption>
</figure>It is a control on authority, not a description of method. The permit says who may do this work, where, when, and under what conditions — and, crucially, that someone competent has checked those conditions are in place before it starts.
Typical uses are hot works, confined space entry, work on live systems, excavation near services and roof work. What they share is that the consequence of getting it wrong is severe and the safe state has to be verified rather than assumed.
Closing the permit matters as much as issuing it. An open permit means the site believes work is still live, and hot works in particular carry a post-work watch period precisely because the risk outlasts the task.
What goes wrong in practice
- Permits issued for a whole day or a whole week, which defeats the point of a time-bound authorisation.
- Not signed back at completion, leaving permits apparently open across a site.
- Conditions listed but never verified before issue, so the permit records an intention.
- Hot works closed immediately at the end of the task with no watch period observed.