Upon applying excessive voltage to a cable, rather than the cable being destroyed, the server gets crashed with the following error: https://hastebin.com/vesowebure.rb
After restarting the server, the cable is gone and all seems to proceed normally.

I have not tested this on single player, only on Kettle version git-HEAD-a8543ec, Forge version 14.23.5.2812 (MC 1.12.2), IC2 Classic version 1.12-1.5.4.5.

This is most likely a bug in Kettle. I can reproduce this crash when running a kettle server, but I can neither reproduce that in a in a single player world nor on a forge server (using IC2 Classic 1.12-1.5.4.5 and forge 1.12.2-14.23.5.2818)

Also note, that Kettle itself is still considered unstable and not ready for production use as they state (source)

@thekdub this looks like a Kettle server.
After rummeging through the Issues of that server type they are rewriting their server code right now.
So this isn't a IC2Classic issue its the Kettle server not performing how minecraft should be performing.

So closing both issues. Because not IC2Classics fault.

Small update from my side: As Kettle builds upon forge 1.12.2 - 14.23.5.2838 (according to their github project) I just tried it using that version of forge (server and client side) to make sure its not a problem with some forge side changes, but I still cannot reproduce this issue and #372 using a forge server or a single player world