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Is it ok to use the brass rod grounding at a subpanel as long as the ground and the neutral bars are isolated at the sub panel from each other?

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A grounding electrode (ground rod) serves a totally different purpose than the equipment ground run with the feeder. One does not, and can not, take the place of or be used for, the other.

For a feeder run to a sub-panel for quite a few years now you MUST run a 4-wire feeder; two hots, neutral, ground. If the panel is in a detached structure to the house then you must also install grounding electrode(s). There are several ways to accomplish this, but ground rods are the most common. Typically two ground rods are required.

Even with older codes that allowed a "3-wire" feeder (where the ground was omitted and the neutral served both purposes) a grounding electrode was still required.

Bottom line to remember for sub-panels: detached structure needs grounding electrodes, attached or within the same structure does not.

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  • Thank you that is very good information to know . my main disconnect panel 200 amps I have an a grounding rod and I have and equipment ground running to a water line further I have the equipment ground bound to the neutral bar resolving back to the grounding rod basically the equipment ground and the neutral electrode the ground rod are band together. In the main disconnect panel is this good to have everything resolving back to the grounding rod basically? – Steve Howerton Nov 7 '15 at 1:50
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    From what I can surmise it all sounds right, but you have it backwards. In the main panel everything resloves back to the neutral bar, which is bonded to the panelboard via the neutral to ground bond. This bond is called the "main bonding jumper". This main bonding jumper in the main panel/disconnect only, is what creates the path for the equipment ground, which is the path for fault current to allow circuit breakers to trip and fuses to blow. – Speedy Petey Nov 7 '15 at 1:55
  • This topic is quite deep and cannot be adequately explained in a few message board posts, if you are interested you can search the web, there is a lot of good info out there. – Speedy Petey Nov 7 '15 at 1:55
  • that is very interesting. Thank you for that perspective on tripping the breakers. If I May digress, is it ok to have equipment ground tied to a water line in the sub panel? And we already know that the neutral and the equipment ground in the sub panel are isolated. Thanks for your time . – Steve Howerton Nov 7 '15 at 2:05
  • @SteveHowerton The water line should be bonded to the equipment grounding system, yes -- but it is not a ground electrode -- you'll want to drive a rod for that. – ThreePhaseEel Nov 7 '15 at 20:19

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