Enclosure using protection by pressurisation type ‘p’, may have internal equipment which have to remain energised in the absence of overpressure. Such equipment must be protected in accordance with the Zone in which the enclosure is located. A typical example is an anti-condensation heater within a pressurised machine which will be energised when the machine is idle.
Equipment outside the machine enclosure, e.g. junction boxes, pressure sensors etc., will also have to be protected in accordance with the Zone.
Note: Since anti-condensation heaters are normally ‘live’ when a machine is idle, a notice warning of this danger should be displayed.
