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Ground rod

New postPosted: Wed May 18, 2011 11:37 pm
by Marc M
Jerry,
What really constitutes the necessity for a ground rod or the clamp to be protected? 250.53
If its in a planter, under the panel on the side of a walkway etc...
This section also says it must be flush, and embedded the full length, and then gives the exception 250.10 (I think)?
Just wondering...I have never seen one protected or buried flush.
Marc

Re: Ground rod

New postPosted: Thu May 19, 2011 7:31 pm
by Jerry Peck - Codeman
Marc,

First, the *minimum* length a grounding rod or pipe is required to be in contact with earth is 8 feet, if the grounding rod is 8 feet long, then the entire 8 foot length would need to be in contact with earth.

While 10 foot grounding electrodes are available, it is extremely rare (in my experience) to find a 10 foot long ground rod used on residential property - however, if a 10 foot rod is used, then the minimum 8 foot burial depth could be achieved with 2 feet of the rod sticking up out of the ground. If an electrician tell you the partially buried ground rod is a 10 foot rod, have them prove it (it is easier to just drive it the rest of the way into the ground).

If the ground rod is driven all the way into the ground, the connector for the grounding electrode conductor to the ground rod must be accessible for inspection, and must be protected from physical damage. Some AHJ will allow the top of the ground rod and the connection clamp to be just below grade level and left exposed for the inspection, then covered up afterward. Other AHJ will require a protective sleeve of some type be places around the top of the ground rod and the clamp, leaving it open for inspection and be protected from physical damage by the sleeve.

The ground rod clamp needs to be protected from damage least it become loose and/or the grounding electrode conductor be damaged - even in a planter ... especially in a planter ... where a shovel could easily cause damage to the clamp or the conductor, or cut the grounding electrode conductor.

Not sure if I covered all the questions you were asking?

Re: Ground rod

New postPosted: Fri May 20, 2011 10:36 am
by Marc M
Hey Jerry,
You answered my questions, here is an image of what I am talking about.

Re: Ground rod

New postPosted: Fri May 20, 2011 5:59 pm
by Jerry Peck - Codeman
Marc,

That raceway the grounding electrode conductor is in looks like spiral wound flexible metal conduit - first and foremost, that needs to be bonded to the grounding conductor/ground at each end; second and also foremost, that really should have a bonding conductor inside that spiral wound metal flexible raceway, otherwise a high current going through the grounding electrode conductor to ground will also go through that metal conduit, and the spiral wrap of the conduit metal will create a choke coil effect and stop the flow of current to ground a built-in feature which is NOT wanted nor desirable.

The best thing to do is to remove that spiral wound flexible metal conduit and replace it with either EMT or PVC (the EMT would need to be grounded at each end, the PVC - obviously - would not need that).