Yes. The GregTech machine you hit with a pickaxe will always explode. It also sends a pulse through the wire that will damage machines it reaches.
That pulse starts as a 32EU packet, then 128EU, then 512EU and finally 2048EU. If the cabling between the machine you hit with the pickaxe is vaporized by the 128EU packet, the 512EU never reaches it.
Nobody, especially me, said you can create a design where the machine you hit with a pickaxe isn't destroyed. The solution is to not hit machines with pickaxes.