One of my greenhouse propagating units was giving very erratic readings, and the control of temperature was bad.

The setup just consists of a temperature controller, temperature sensor and heating element. The controller was installed in an IP rated plastic box, located within the greenhouse. The IP rating was IP65 Enclosure – IP rated as “dust tight” and protected against water projected from a nozzle.

But in opening the box, this is what I found. Somehow water or humidity had ingressed into the box. Either through the cable glands, the controller itself or its sealing gasket, or the box lid gasket.

The actual sticky label on the side of the temperature controller was disintegrating, and unreadable.

Here is the problem, all of the terminals on the back of the controller were all badly corroded. Notice the cob webs as well ?? Strange.

I could not take the photo of the plastic box gasket as it had perished into dust and was letting in the water and spiders.

Even thought the installation was OK, with 30mA earth leakage fitted. It is in hindsight worth checking all electrics in a greenhouse on a regular basis, by a suitably qualified electrician. Especially where the equipment is of non UK manufacture.