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ra_doliv 09-02-2007 05:20 PM

Ground rod blues!!!
 
OK you pros -- here is my problem. I have a 1970 built house that is has no ground rod at all. The service panel ground goes from the panel to the cold water pipe at the hot water heater --- about 10 feet away. I want to bring the system to current code levels ref grounding and plan to do the following: drive two ground rods at least six feet apart and bond a #6 or better from the furtherest ground rod to the nearest ground rod and from the nearest ground rod to the cold water pipe. My concern is that closest place to drive the ground rods is about 50 feet away unless I jackhammer up concrete to reach the earth.

I have no issue with going up to #4 because of the distance involved. What do you guys think?? Is my plan on routing and distance ok, or will I really not improve over what I currently have??

Thanks for any help/comments!!

Don

Speedy Petey 09-02-2007 07:06 PM

Do you have a well or municipal water? How close to the water heater does the water enter the house? What mater is the water piping entering the house?

The GEC (grounding electrode conductor) carries no current, so the distance is not a factor. The only reason to go up to #4 is if the #6 will be in harms way.

Adding a ground rod will not "improve" anything about your system. It will help,a bit, in the case of a lightning strike nearby or if a POCO transformer blows and surges the voltage considerably.
Ground rods have absolutely NO effect on the everyday workings of your electrical system.

What is it you are trying to achieve?

ra_doliv 09-02-2007 08:10 PM

Speedy --- thanks for your quick response!

I am on municipal water service. The water actually enters the house about 50 feet from the water heater and the feed from the city meter is pvc. I don't know if it was that way originally or changed out.

I am trying to upgrade all parts of the electric service to current code and my understanding is that current code would not allow a cold water pipe as the ONLY ground -- it has to be backed up by two ground rods six feet or more apart. My logic is that if the code requires it now, there must be a valid reason for the code change that is probably safety related plus I am concerned about the quality of the cold water pipe ground with a pvc feed.

Thanks again!

Don

Speedy Petey 09-02-2007 08:42 PM

With a PVC water entrance you have NO cold water pipe ground. What that wire is doing is simply bonding the metallic water piping system in your house. This is so that if the water piping becomes energized somehow it will create a short circuit and open the circuit breaker. Without this bond the piping system would remain live with voltage. Obviously NOT a good thing.

Right now you have no grounding electrodes. Adding two ground rods would be a good idea.

Stubbie 09-02-2007 08:49 PM

EDIT: I see Speedy has replied and my post is somewhat redundant to his but maybe useful anyway.

Using the water pipe with PVC feeding the house is pointless. If the metal water pipe was in contact with the earth for 10 feet after it left the house then the water pipe could be used for the electrode NEC 250.52(A)(1). In your case it serves no purpose. You need to drive ground rods or use a plate electrode. See image below in your case you can use any electrode starting with #3. Run #4 or #6 solid copper back to the neutral/ground bar in the service panel. Be very careful when your inside that panel. Best to Turn the main breaker off to get all the neutral current off the neutral bar. Read this article and reference the graphics posted here and on the article.... ground rods are probably your best bet. You must try to drive them vertically example (A) if not possible then B and C are allowed.

http://www.mikeholt.com/newsletters....ay&letterID=96

http://www.mikeholt.com/onlinetraini...13918661_8.jpg http://www.mikeholt.com/onlinetraini...13918256_2.jpg


Stubbie

ra_doliv 09-02-2007 10:38 PM

Thanks guys --- think I am getting it!! Still want your input on the distance of my grounding electrode wire run and the install order. The diagrams seem to imply the ground rod will be driven in the immediate vicinity of the meter --- mine will be 50 feet away ----ok???

Then the order: 1) G rod 1 driven 2) G rod 2 driven 6 feet away 3) connect GR 1 to GR2 with approved clamps and #6 4) run #6 from GR2 to cold water pipe and connect with approved clamp 5) continue #6 from cold water pipe to service panel and connect to nuetral bar (after disconnecting main).

Sorry to be a pain --- just want to do it right and only once!!

Don

Stubbie 09-02-2007 10:53 PM

Yes Don.... that will work and by hitting the cold water pipe even though it is no good for an electrode it will provide the required bonding of the water line to the service enclosure by the NEC for a ground fault path in the event your metal pipes in the house ever become energized. It is becoming common for a bond to be made at the hot water tank between the cold and hot water pipes so both are bonded around the insulated tanks dielectric unions. So you might want to do this also.

You can run the 50 feet it isn't an issue. They are for lightning and high voltage events nothing to do with the working electrical supply to the home. 50 feet is just a spit for a lightning strike having thousands of volts.
Don't splice the #4 at the first ground rod it comes to and put both wires under the same acorn clamp. If you want to cut it then use two clamps at the ground rod then run to the second one from the second clamp. Or keep it continuous but make sure you don't kink the conductor at the clamp where it will loosen and lose its bond.


Stubbie

ra_doliv 09-02-2007 11:31 PM

Stubbie,

Thanks for the tip on the hot water heater -- I will do that while I am at it. I appreciate the heck out of guys like you and Speedy that spend your time helping out the DIY crowd!!

Don

Stubbie 09-02-2007 11:48 PM

No problem Don... good luck. If it is easier you can run a separate wire to the water pipe and bring it back to the panel service neutral bar.

Stubbie


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