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[on:]

My potted plant watering system has moved on a few steps.

Now I am needing to think about how it will be encased.

Fogetting the size, shape etc, here is what I know:

240 (mains) voltage going in.
SMPS (semi caged)  in the unit to power the arduino, and electronics.
There is a pump  and 5 solenoids and the appropriate hoses.
The connections will be re-enforced with cable ties making sure the hose doesn't pop off the spiggot.
(I'm being overly cautious.)

So:
This box - so far about 400mm x 400mm x 100mm - is going to be outside Facing EAST.
It will see a bit of sun in Summer but not too much in winter.
It will have 6 x 10mm pipes going to it and 1 x 240 (mains) cable.
I'm guessing that will be an IEC (kettle) connection.

Inside I know I will have to keep the 240 and the water very well seperated.  What I probably will do is have a "mains" and arduino section with basic seperation between the two, and a "water" section where the pump and solenoids are.

But the point where I am getting stuck is humidity and ventilation.
I'm guessing the power supply will handle the load ok, bt will need air flow to reduce condensation.
I don't want water to condense on the supply and allow all the magic black smoke to escape.
But, if I have it in an too well ventilated area, the rain may get in and cause the same problem.
As well, the cockroaches will probably nest there if the hole is too big.

Thoughts?

[Reply #1 on:]

I'd Highly recommend separating the water control from the electronics by using a separate Nema 5 or better box for the control stuff and a semi open one for the watery end. The Box could face south (In the northern hemisphere) and have a solar panel as well But connect the control to the water with a "Sealtite" type of conduit and remember to leave a vent on the bottom. Use a small plug of more or less loose glass wool to keep out the crispy critters and you won't have many issues with condensation, Don't and your boards WILL get water damaged. All of my early ones suffered from that issue until I learned how to 'fix' it. what happens is the box heats up during the day and when it cools it will pull in the evening moisture laden air which condenses but somehow never escapes. Wasps, mud daubers and carpenter types like the boxes for nests too. I've been surprised a number of times... I hope this helps.

Bob

[Reply #2 on:]

This environment is why some PCB's that are exposed to the elements should be coated in a water proof conformal coating... which range from  Acrylic and Silicone coatings to the other extreme... epoxy based coating.

I use a coating on the PCB's in my weather station.

[Reply #3 on:]

Thanks both.

Yeah, if possible, I will put the mains and Arduino in a smaller box inside the bigger one.

Then all that goes in to the bigger box is the 12v DC wires.

The mains is contained in the smaller box with the SMPS and arduino.

I'm "down under".  Solar pannels are a bit too much cost for the use.  It is already costing me $200 and that is only to water 5 potted plants on my balcony.   

Yeah, I will put a hole on the underside to allow any water which accumulates to escape.

Time for more thinking.