Safely Controlling High Power Devices

Hi everybody,

I've understood how to control a relay with my arduino, but I'm not sure of how really do this in permanent projects (therefore, safely).
Let's assume I wanna drive a little DC cooler, powered by public electric source, with my arduino :

  1. Where I should plug the relay? (Obviously not in the wall plug :slight_smile: ) Should I cut off the wire of the cooler (after the AC -> DC transformer) and connect the wires inside to the relay?
  2. There are some precautions I should take? Maybe I should put a fusible somewhere?
  3. There are some already done components I should buy to build such circuit more safely? For example a connector for the relay-load link?

Thanks in advance,

How are you getting power for the DC cooler now?

For DC I like to use Anderson Powerpole connectors, the small ones can go up to 30 Amps. And they cost about $1US for each termination.

Feed power into a box. through a fuse. to your relay. from the relay to you cooler.

I like to make things like the box with a connector on the input and output. That way you can plug the cooler directly to the DC supply, or break the connection to the DC supply and insert the relay box into the cable and control it through the relay. Nice to be able to use the cooler while you are working on the bugs. Also nmeans the relaybox can be used for something else easily.

That is a good way to hurt your cooler and yourself. Or to hurt someone else.

Ok, I had not a lot of time lately to check the forum...

First, I changed my mind and now I'm powering the cooler with AC (it can go both way)
Second, What do you mean for "feed the power into a box" ? I mean, what kind of box, there are specific ones?
Last, "DO NOT USE A CONNECTOR SIMILAR TO YOUR STANDARD AC MAINS CONNECTOR", (this looks pretty important :slight_smile: )
I don't get which connector should not be similar to my standard ac main connector (the one that goes from public power source to relay box, or the one that goes from relay box to the cooler.

Another question, inside the box there are particular safety technique I should know? (minimum distances between wires, insulation material I can add between them ...I don't know just guessing)