Keeping equipment cool in outdoor enclosures

This question is more for users located in dry and very hot areas.

We have been wondering about best practices to keep our power supplies switches and UPS as cool as possible inside outdoor, fan ventilated NEMA boxes.

Temperatures in northwestern Mexico easily reach 45c (113f) during summertime, just like Arizona, we are located down the border.

These fiber glass boxes isolate heat much better than metal and the fan kicks in at 22c (72f)

We looked at some refrigerated boxes but they where prohibitively expensive (and large) and have to settle for these $300 boxes.

Here are some pictures. Thanks in advance for the help!

Bare with me here. We have an operation in Arizona where in one case we use a small refrigerator that is modified to fit equipment in it. We used this same technique in Panama City, Florida where our Cisco router is located in a hot pool house. We have had no issues with doing it this way. I wish I had pictures to pass along but I don’t. Using these refrigerators compared to a $300 box has done wonders. Drill a few holes in the side for cables, seal it back up and you are good to go. Don’t call me Crazy, Don’t call me Cheap because it works very well. :lol:

You’re crazy and cheap! Thats actually a pretty good idea, I was looking to make my own outside enclosures but was thinking more on the reflective outside with very thin insulation and fans, etc.

Also if your installation doesnt allow small fridges we currently have a box that was made for us (a free demo, what a great deal) that has a small heater/AC unit on the side of it. Its pretty cool and maintains the temp. I will find out how much these cost and let you know.

check these guys out they have all sorts of cooling goodies

I agree, that’s a pretty good idea!
I have found a small Haier 1.7cubic Ft fride at the local walmart store for less than $90. It has no moving parts and uses thermo electric cooling so it has no coils.
I will drill a hole on the side and install a screw on gasket to run the wires in/out. We’ll make a white metal enclosure with an exhaust fan and put the fridge inside.
I’ll send pictures once it’s completed.
BTW, JLewis. Do you have any condensation issues on your refrigerated boxes?

I would discourage the use of a cheap refrigerator. It is not designed for this application and will expire quickly. Once it fails, the gear inside will bake until it too fails (UPS will go first). Murphy’s Law says it will be on the hottest day of the summer.

The problem I see with your current cabinet is:

A: Too small for the amount of gear stuffed inside
B: There is no heat shield so the cabinet is absorbing all the UV
C: Consumer equipment not designed for harsh environments

A passive solution is to find or make an enclosure that your enclosure can fit inside with 2" additional space on all sides. Stand the internal cabinet off the back wall of the outer cabinet.

Paint the outer cabinet with reflective paint (same stuff they paint roofs with). It will reflect up to 50% of the sunlight before it ever hits the outer cabinet. The gap will keep the inside cabinet close to ambient which should be OK unless your ambient gets to 120 in which case the little Wal-Mart refer isn’t going to survive anyway.

Create a vent at the top and bottom so the fan in the inside cabinet has somewhere to vent to.

FYI, that TrippLite UPS is not designed to operate in extreme environments (104F max). Test often and check for leakage.


I know price is a concern but I feel you should at least know what is out there…

The best method obviously is a purpose built cabinet. I have spec’d a few jobs with products from DDB Unlimited. I really like their pad mount boxes with the side mount AC unit. These boxes also have sunshields. You can really go to town and accessorize them with fans and heaters too.

Here is a link to one of their top sellers. I’ve quoted similar systems before: … sures.html

I will have to disagree with you Jerry. 3 years and going strong on the installation in Arizona and 2+ years now on the one in Florida. Seems to be working pretty well. :wink:

Are you using consumer grade units the one you can pickup at your local Walmart store?

If i have to replace them every two or three years I will be in much better shape than I am now.

Both were bought at a local hardware store Home Depot and Lowes. cost was at or around $75.

That’s pretty cool.

I guess I have a different philosophy about using equipment outside it’s performance envelope. I’d certainly want some type of monitor/alarm on it.

I have been looking for temperature monitoring devices and found this:

You will also need the temperature sensor module.

It also has dry contacts so you could add a tamper switch.

After a couple of months of testing a few inexpensive technologies to keep our equipment boxes cool we realized that the refrigerator approach did not worked.

What we did instead was having one our installers manufacture a metal case, spray the inside with insulation and add a 5000BTU small A/C ($90US) to the side of it.

The box was also equipped with a Giest RS-MINI environmental Sensor ( ) that monitors internal temperature, electric power condition, and door position with a dry contact closure sensor. You can add all kinds of sensors to this little controller.

The power backup is being provided by an Alpha Novus outdoor UPS.

The enclosure has been running smoothly for over a month with an internal average temperature of 30C with a fluctuation of +/- 3 degrees (when the outside temperature was well over 42c in the Sonoran Desert), this is with the A/C unit set to the minimum cooling possible.

Here’s some pictures, its not too fancy but keeps the equipment secure, clean and cool with plenty of room to add more gear in the future. … 24x768.jpg … 24x768.jpg … 76x768.jpg … 76x768.jpg … 24x768.jpg


why did you go through all that trouble just to air-condition your CMM?

you know they’re meant to mount outdoors, right?

Yes I know the cmm is meant to be used outdoors.

The cmm end up being there after a tower climber step on it on his way up this busy tower damaging the mounting brackets. The purpose of the ac is basically to cool off our switch and ptp400 pidu.

We lost a pidu at that location due to high operating temperatures.