Ground plates as opposed to rods?

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Old 05-09-06, 11:34 AM
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Ground plates as opposed to rods?

At a sub panel in a separate building to which a water pipe will be run, I thought, I was required to install ground rods. I was not looking forward to driving these down into the ground ten feet. A friend suggested using a metal plate as opposed to rods. I checked the local code and these are allowed. The books I have make little mention of ground plates. Are there issues regarding plates? While I live in the PNW with lots of rain, the rapid run off leaves the soil very dry during the summer months. Thank you.
 
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Old 05-09-06, 12:13 PM
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Is the water pipe metal?

Chris
 
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Old 05-09-06, 01:56 PM
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There are seven allowed grounding electrodes; a grounding plate is #6. The plate must be at least 2 square feet and buried at a minimum depth of 30 inches. The code recommends deeper burial if soil moisture is not consistant at 30 inches. The plate must be 1.5mm thick if copper or 1/4 inch thick if steel and have no paint or other coating.

Unless you are very close to bedrock, driving a rod will probably be easier than digging the hole for the electrode plate.

If the water pipe to the building is metal, and is in contact with the earth for 10 feet or more, you may use the pipe as the grounding electrode.
 
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Old 05-09-06, 02:17 PM
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Is there a standard method of bonding the ground wire to the plate? Thank you for your time.
 
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Old 05-09-06, 02:43 PM
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It must be done with "an approved pressure connector" or "exothermic welding". Ask at an electrical supply house (not big box store) and see if they can find you a clamp for the purpose.

Grounding plates aren't really used around here, but the materials might be easier to find in your area.
 
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Old 05-09-06, 02:49 PM
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If the water pipe to the building is metal, and is in contact with the earth for 10 feet or more, you may use the pipe as the grounding electrode.
Actually you must use the water pipe if it meets the requirements of 250.52(A)(1).

250.50 Grounding Electrode System. All grounding electrodes as described in 250.52(A)(1) through (A)(6) that are present at each building or structure served shall be bonded together to form the grounding electrode system.

So if the water pipe is metal for 10 feet you must use it as a grounding electrode. If you have footing steel at the separate structure, that meets the requirements of 250.52(A)(3) you must also use that as a grounding electrode.

That is the reason that I asked the question about the water line being metal or not.

Chris
 
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Old 05-09-06, 03:56 PM
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My orginal plan was to go with metal pipe since that is what I know. However, friends tell me PEX is an easier way to go. Is it acceptable to go with metal underground and switch to PEX in the cabin? Similarily, would it be acceptable to run PEX from where I cut into the copper in the main house to the metal underground line or am I just courting trouble? Thanks
 
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