Turning Archive

Subject:
Lightning and neutral wire question

Chuck Jones -West TN
I have done a lot of electrical wiring... which means I still have a lot to learn. I have always been careful to connect ground/neutral wires to ensure an early circuit interruption in case of a fault.

A friend's Jet 1642 (240volt) VFD was fried recently during one of our frequent lightning storm. He had the lathe wired through a 2-pole single throw switch of adequate size and he always flips that switch off when he leaves the shop. In conversations with Jet Tech Support they told him that even if the switch was off lightning could still run in on the neutral/ground wire and ruin the VFD. Sure enough the Jet installation instructions (which we all read thoroughly before installing) state that the lathe should be wired through a "3 or 4 pole" single throw switch (even the 120volt version). My friend has opted to unplug the lathe rather than try to sort out the confusion. Says he'd rather turn wood than try to understand electricity.

I have bought 3-pole switches for my lathes with VFD's, but I'm a little uncertain about installing them.

Any opinions welcome.

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