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With a recently renewed spark of interest in electronics, I’m now starting to solder stuff and build more permanent devices than before with breadboards.

But with great power comes great responsibility!

Some of these devices may eventually be powered on 24/7, without adult supervision. While I was pretty confident I could unplug a breadboard while watching it, I don’t have the same peace of mind considering permanent devices.

Worried by videos of raspberry pi catching fire, and other diy electronics going really wrong, I started looking for guides on... you know, safety. Alas, I found nothing with enough details.

I know not to tinker with mains. I know transistors can get really hot (burned a finger once). But that’s it really.

So.

As the various comments pointed out, there’s no hard and fast rule for safety, and I should test my circuits. Makes sense.

However, being new to the field, I’m unsure what to test for. Overcurrent could be one thing, but further than that, I’m lost.

What are the main safety tests that a circuit design should go through before being left unsupervised?

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closed as too broad by Elliot Alderson, Bimpelrekkie, DoxyLover, pipe, Scott Seidman Oct 22 '18 at 19:50

Please edit the question to limit it to a specific problem with enough detail to identify an adequate answer. Avoid asking multiple distinct questions at once. See the How to Ask page for help clarifying this question. If this question can be reworded to fit the rules in the help center, please edit the question.

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    \$\begingroup\$ Given that even professional things sometimes going really wrong there can't be a failsafe guide \$\endgroup\$ – PlasmaHH Oct 22 '18 at 18:50
  • \$\begingroup\$ Just more smoke detectors and fire extinguishers at reach.. \$\endgroup\$ – Eugene Sh. Oct 22 '18 at 18:57
  • \$\begingroup\$ @EugeneSh. CO2 fire extinguishers, not powder. Otherwise one small mistake destroys the entire room. \$\endgroup\$ – Jeroen3 Oct 22 '18 at 19:08
  • \$\begingroup\$ @Jeroen3 details on that? \$\endgroup\$ – Antoine_935 Oct 22 '18 at 19:09
  • \$\begingroup\$ A CO2 fire extinguisher only emits gas. This leaves no residue. A powder one emits toxic corrosive powder. Everything electronic in the room can be tossed. Go learn about fire extinguishers! \$\endgroup\$ – Jeroen3 Oct 22 '18 at 19:16
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For being on the safe side, you will have to get professional. And what distinguishes a PRO from a beginner?

The beginner only thinks of what he can do to get the circuit working. Once the circuit is working, the job is done.

A PRO thinks of all reasons that could go wrong with the circuit and most importantly, he makes a lot of tests (I.e. short circuit tests) to verify if the circuit behavior during failure.

So this is not a question of which book to read, but it’s a question of your attitude towards building a (safe) circuit.

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  • \$\begingroup\$ That sounds wise, but it is my problem actually. I don’t know what can go wrong and how. I was hoping some resource exists that lists the most frequent issues, or at least how to test for them. \$\endgroup\$ – Antoine_935 Oct 22 '18 at 19:57
  • \$\begingroup\$ Start with the power supply of your circuit. What happens if you short this power supply? How hot will it get? \$\endgroup\$ – Stefan Wyss Oct 22 '18 at 20:01
  • \$\begingroup\$ Hey that’s a good question, I don’t know. I was mostly planning t use wall adapters, but I’ll test this. Not without a fire extinguisher though. But unless I have some computer doing that for me, I can’t possibly test all the combinations of shorts in a circuit, can I? How to select what to test first? \$\endgroup\$ – Antoine_935 Oct 22 '18 at 20:07
  • \$\begingroup\$ You could also add a fuse to your power supply and test this setup. BTW: You normally don‘t need to test all short circuit possibilities in your circuit, because it’s not the short circuit that produces heat (because a short circuit has low impedance), it‘s the driving source (e.g. power supply) that can catch fire if you have a short somewhere in your circuit. \$\endgroup\$ – Stefan Wyss Oct 22 '18 at 20:14
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    \$\begingroup\$ if you use a wall wart type of power supply, then it should already have the necessary over current protection built in, as long as it has the correct labeling from UL or other testing agency (i would not trust cheap asian knock-offs with questionable labeling) \$\endgroup\$ – jsotola Oct 22 '18 at 21:54

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