How to heat the case of an outdoor transport router?

Question

network hardware

Tell me a good solution for heating the case of a street transport router (an iron box measuring 500x100x100mm), from -20 to 0 degrees.
I considered a thermal cord and a thermal relay that is triggered by temperature, but they are difficult to get or they are very expensive (together - more than 600 rubles).

Answer 1

It's not just about temperature, it's about rainfall.
take an aquarium that is suitable in size, sprinkle salt down (it will absorb moisture), a grate on it, like in a sink, so that the body does not touch.
then you take a piece of foam plastic, thicker, punch holes for wires, cut out grooves according to the walls of the aquarium, bring out the wires, put the foam plastic on the aquarium.
Sealant is poured where the wires were brought out. for the final calm, you can spray the foam on top with hairspray or paint it, and glue two empty five-liter bottles on the sides of the aquarium for a moment, then even in the event of a flood, the structure will work properly swaying on the waves within a radius of the length of the wire)

Answer 2

An ordinary incandescent lamp of 40-60 watts will help you

Answer 3

What is a thermal cord? For aquariums? Instead, you can use a cable from a warm floor or powerful resistors of 10-30-50 watts. You can also just buy a heater for aquariums.

Answer 4

In fact, if you put the router in a closed box, it will normally winter, I have worked for two years with a router with Wi-Fi on the street in Novosibirsk in a metal box, the main thing is not to flood with rain. The temperature is -40 + 40. There have never been any problems due to freezing or the like.