I've installed a subpanel and need to ground the grounding bar to the actual panel box. I was instructed to run a #6 jumper to a hole on the box, attach with a screw, making sure to 'tap threads'. Unfamiliar with the term 'tap threads', what do I need to know?

  • Aren't subpanels not to be bonded?
    – Mazura
    Commented Jan 31, 2015 at 3:17
  • I can't answer this question with any sort of expertise, but during final inspection the inspector indicated this needed to be done. After googling around, I did find this: House Wiring, which supports that direction.
    – dsurq
    Commented Jan 31, 2015 at 3:31
  • Disregard, I was thinking of the neutral.
    – Mazura
    Commented Jan 31, 2015 at 3:40
  • Sounds a bit wrong IMHO. A ground bar should come with screws to mount it straight to the panel with shipped screws appropriately sized and colored for this application. Secondly, tell Mr. Inspector to come up with better advice - #6 wrapped on a screw; are you kidding me; how big of a screw did he tell you to use? Commented Feb 1, 2015 at 3:42

2 Answers 2


"tap threads", likely means to use a tap to make threads in the hole.


Keep the tap straight up and down. When (or before) it gets hard to turn, back it out to clear the chips. On all but cast iron, use oil as a lubricant.

I'd use a lug instead of wrapping it around a screw.

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  • Thanks for the tips. I like the idea of a lug--I'll likely go this route.
    – dsurq
    Commented Jan 31, 2015 at 3:26

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