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Old 04-19-2012, 10:56 PM   #21
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Thanks for all the feedback fellas, hopefully we'll do this again soon...
Hope we helped, welcome to the Forum, come back soon.
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Old 04-19-2012, 11:06 PM   #22
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Hey how's it going out there, I'm pretty new t this forum but I'm an apprentice electrician in ohio and I want to know if there is ever an instance where and electrician has to "up-size" his/her grounding conductor for long distances as if they were accounting for voltage drop?
The grounding conductor has only to be sized to the OC device.
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Old 04-19-2012, 11:08 PM   #23
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The grounding conductor has only to be sized to the OC device.
You may want to read the thread ......
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Old 04-19-2012, 11:23 PM   #24
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You may want to read the thread ......
I did, and I thought that I understood it. The "ground", or egc, has no need to be any larger than the conductor attached the the OC device. Are you saying that that is incorrect?
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Old 04-19-2012, 11:29 PM   #25
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I did, and I thought that I understood it. The "ground", or egc, has no need to be any larger than the conductor attached the the OC device. Are you saying that that is incorrect?
As BBQ posted before, read 250.122(B). If the circuit conductors are increased, the EGC must also be increased.
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Old 04-19-2012, 11:51 PM   #26
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As BBQ posted before, read 250.122(B). If the circuit conductors are increased, the EGC must also be increased.
Aren't we saying the same thing?
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Old 04-19-2012, 11:55 PM   #27
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As BBQ posted before, read 250.122(B). If the circuit conductors are increased, the EGC must also be increased.
Okay, let's say that in a 20 amp protected circuit a person would decide to increase the circuit conductor size to, let's say...#8. What good would it do to increase the size of the equipment grounding conductor?
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Old 04-20-2012, 12:17 AM   #28
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Okay, let's say that in a 20 amp protected circuit a person would decide to increase the circuit conductor size to, let's say...#8. What good would it do to increase the size of the equipment grounding conductor?
If you increase the conductor due to VD or for other reasons, you need to increase the EGC, due to the same losses that would occur in the EGC during a ground fault, even if you increase the conductor for derating reasons the available fault current the energized conductor will be increased, hence you still need to increase the EGC.
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Old 04-20-2012, 03:17 AM   #29
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Okay, let's say that in a 20 amp protected circuit a person would decide to increase the circuit conductor size to, let's say...#8. What good would it do to increase the size of the equipment grounding conductor?
I am not sure, nor do I care if it does anything. But the code requires it.
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Old 04-20-2012, 08:14 AM   #30
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...We have done some large warehouses that the plans called for 4 AWG copper for the 20 amp circuits supply some receptacles.
You recall what the distances would be for something like that? Are they trying to keep 3% drop?

-John
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Old 04-20-2012, 11:21 PM   #31
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If you increase the conductor due to VD or for other reasons, you need to increase the EGC, due to the same losses that would occur in the EGC during a ground fault, even if you increase the conductor for derating reasons the available fault current the energized conductor will be increased, hence you still need to increase the EGC.
The egc does not have to carry any more current than the circuit protection allows.
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Old 04-21-2012, 01:49 AM   #32
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The egc does not have to carry any more current than the circuit protection allows.
It might be because the available short circuit current would be greater than normal if the current carrying conductors are larger than normal.
So, the EGC needs to be larger than normal to clear a fault.
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Old 04-21-2012, 11:22 AM   #33
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The egc does not have to carry any more current than the circuit protection allows.
And your contention is this is not affected by distance, added resistance/impedance?
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Old 04-21-2012, 11:52 AM   #34
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I have a similar question. What about ground pigtails and or pigtails in general.

Example
You have a 20amp circuit and you up sized to 10awg for whatever reason. Can you use a 12awg ground pigtail to ground your box and/or pigtails to recep?

What about grounding a jbox with a 12awg with a 30amp circuit passing through?
The code doesn't require the wire size be maintained throughout the entire circuit. We routinely start out with a large wire for voltage drop and go down the closer we get to the end of the circuit. So... a #10 circuit could have #12 device tails so long as the OCP is 20 A.
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Old 04-21-2012, 11:54 AM   #35
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What happened to the good ole days of half sized grounds such as the #18 and 16 for 15 and 20 amp circuits. Why did they change it to full size grounds for 30 amp circuits and under?
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Old 04-21-2012, 12:14 PM   #36
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Originally Posted by RIVETER View Post
Okay, let's say that in a 20 amp protected circuit a person would decide to increase the circuit conductor size to, let's say...#8. What good would it do to increase the size of the equipment grounding conductor?

If you increase a #12 to a #8 wire then generally speaking there is a long distance involved. The #8 will carry a lot more fault current and if the egc is not increased then the impedance on the #12 is greater and it may not carry the fault.

If the #12 is increase to a #8 then the egc must be increased to a #8
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Old 04-21-2012, 12:23 PM   #37
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What happened to the good ole days of half sized grounds such as the #18 and 16 for 15 and 20 amp circuits. Why did they change it to full size grounds for 30 amp circuits and under?
IMO when we had 60A services fed from a 5 KVA transformer 100 ft away w/ #6 AL we only had a few KAIC short circuit current in our homes.

Now we live in subdivisions with 35KVA pad mounted transformers 25 feet from our 400A services, thru 350 Kcm.

With those conditions we now have 20 KAIC in our homes so we need a way to clear a fault when grandma drives a nail in a branch circuit while hanging the family portrait.
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