ECN Forum Forums Technical Discussion Electrical Theory and Applications Right Grounding

I din't know where to post this. Hope this the right place. In the company where I work the grounding has become a big issue. Some of the 200 & 400 amp panels and some XFMR's are grounded on the water pipe, some are grounded to a 8' rod and some are grounded to both. A new journeyman has made an issue about the grounding on water pipes. My question is what is the best and legal (In Torrance California) way to ground this panels and XTFM's. Also all of this panels do not have a ground coming from the main panel board.

To correct this I was thinking of drilling a 8' copper rod next to some of the beams with a jumper. Then removing the grounding wires from the water pipe and putting them to the beams.

There is no way we can answer your question due to the different parts of your electrical supply.

Break down the different parts, into service equipment, feeders, panels not service equipment, and equipment, such as transformers, motors, etc..

Then read the codebook.

Do not assume that adding a rod next to beams will provide for a quality grounded system. In fact, this may create a hazard. You may need to hire a grounding firm to provide the correct specs for this job.

You should also study as much on grounding as you can. It is a specialized field, so if you don't understand it, get help.

What was the new journeyman's concern with the water pipe grounding?

Rick

[This message has been edited by rmiell (edited 10-10-2003).]

I don't think I can fully answer your question if you don't have a code book. If you do, read article 250.50 through 250.70 and also read 250.30.

The code states that if available on the premises wiring sytem, all electrodes must be used. Please do not remove anything from your water pipe.

EDIT: Looks like we posted at the same time! At least our answers were consistent!

[This message has been edited by Ryan_J (edited 10-10-2003).]

A couple of things to remember on separately-derived-system grounding. In many areas, a connection to local building steel is the most desirable for reducing potential differences between gear and most effective for secondary-side overcurrent-device operation.

Also, don’t forget that the primary-side overcurrent device may be far less effective if there is not a continuous equipment-ground conductor between the local-transformer core/frame and the source overcurrent device—maybe in a service-entrance switchboard for smaller installations where plant-owned secondary-unit substations are not installed. These two grounding/bonding connections are clearly for different purposes, but both almost always involve a local drytype transformer.




[This message has been edited by Bjarney (edited 10-10-2003).]