The parts(s) of an IS system which are marked to indicate that they should be installed in a non-hazardous area (associated equipment [Ex ia] etc) may be used in a hazardous area if installed in, for example, a pressurised enclosure as illustrated below.
The enclosure marking would then be of the form Ex p (ia). Indicating a pressurised enclosure with an intrinsically safe output.
![ex p[i] (hybrid)](https://www.eicstech.com/wp-content/uploads/2022/06/ex-pi.png)
