|
| Ek's Home | Forum | Chat | Electrical Links | |
| Subject - Service Ground | |
| Electricman |
The company I work for is a mechanical company so every now and then we get to help out the HVAC fellas when they fall behind, so today I went along for the ride and had the oppertunity to look at one of our compettitors wiring. My first stop was at his service which happens to be a 600 amp single phase , looking at the ground rod I noticed only a #8 solid copper conductor on a single ground rod. My ? is how did this pass inspection? Have any of the inspectors on this forum seen this before?
|
| JimmyDee | I'm sure it didn't pass an on site inspection. This may be a secondary grounding electrode but that doesn't make any difference. Jim |
| Electricman | Jimmy, I checked it out pretty good its the only service ground. |
| Ryan_J | You're right...a 600 Amp service would require a #6. If that is the only thing available, and it meets 25 Ohms, your done. :) So, lets twist this a bit...shall we? Let's say I have a 600A service and I have no available electrodes. I drive 2 rods with a #6, and I have about 200 Ohms, even after the parrallel rods. Same service, one rod, 20 Ohms, but with a #10. Which do you like better? |
| zapped208 | I will go for the 2 rods and a #6 cu. |
| Electricman | Ryan, wouldnt a 600 amp service require a #2 copper electrode conductor? |
| Electricman | Or is 250.66(A) mean that no larger than #6 because the conductor is attached to a ground rod? My employer has always made me use #4 thwn stranded for our 200 amp services is this overkill? I am now really confused on this matter of ground conductor sizing please explain. |
| Electricman | Ok,Ok I just read 250.64 thats why he tells me to use #4 thwn . But this service that is in ? he used #8 solid that was not protected in any way so that in itself would be a violation correct? since it was not fastened to the building and it is smaller than #6. correct? |
| cs409 | here in south east texas, its no. 6 for 100 amp, no. 4 for 200 and so on,,,,or Energy will not connect....nor will it pass local inspections. |
| David Hyatt | If it is the sole connection to a rod, the grounding electrode conductor is not required to be larger than #6 copper. 250:66A I mentioned this in an earlier post. The grounding system has to be 25ohms. Right? I was told if you drive two rods, this would be legal, even if it is more than 25 ohms. Is this correct? |
| JimmyDee | quote: Yes David that is correct. The problem with providing the inspector with the certification that the one ground rod is 25 ohms or less is, the cost of the equipment to do this and the time it takes. It is far easier and cheaper just to buy 2 rods and be done with it. Keep in mind that the rods have to be 6' apart as a minimum. I'm of the understanding that a lot of the local inspectors have not started to push this but it is totally enforced in this area. Jim |
| David Hyatt | They havent but my question is would driving two ground rods reguardless of the 25 ohm rule, would this satisfy code? If you have two ground rods 6 foot apart with 300ohms to ground would you be code legal? I was told if you drove 2 that would release you from the 25ohm rule, and any liabilty that goes along with it. Is this right? |
| JimmyDee | Yes, that is my understanding. Jim |
| Ryan_J | IT would be perfectly legal to ground a 1200A service with one rod and #6 GEC if it meets 25 Ohms, or you could use two rods with a #6 and not even have to test the resistance. You vould have 1000 Ohms, as long as you have two rods you are done. :) |