Increasing equipment grounding conductor

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cppoly

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If the ungrounded conductors increase in size from the minimum size, the EGC is supposes to increase proportionately as well, why?

Table 250.122 lists EGC sizes for overcurrent devices. Wouldn't this alone be used in determining the EGC?
 
cppoly said:
If the ungrounded conductors increase in size from the minimum size, the EGC is supposes to increase proportionately as well, why?

Table 250.122 lists EGC sizes for overcurrent devices. Wouldn't this alone be used in determining the EGC?
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Supposedly when you increase the size of the conductors you are doing so generally because of voltage drop. When you have a very long run the impedance on the egc can be very large over this distance so the conductor may not carry a ground fault. Increasing the egc will alleviate this problem.
 
When does this rule come into play though?

For example, any OCPD from 30 - 60 A uses a #10 EGC. I can use #10, #8, or #6 ungrounded conductor and still use a #10 EGC. If I use a #10 then increase to a #6 in the future, but the breaker still remains in the 30 - 60 A range, does the EGC still need to increase? Because even though it is "increased" to a #6, you are still in the #10 EGC range anyway. Unless, I'm interpreting this rule wrong.
 
cppoly said:
When does this rule come into play though?

For example, any OCPD from 30 - 60 A uses a #10 EGC. I can use #10, #8, or #6 ungrounded conductor and still use a #10 EGC. If I use a #10 then increase to a #6 in the future, but the breaker still remains in the 30 - 60 A range, does the EGC still need to increase? Because even though it is "increased" to a #6, you are still in the #10 EGC range anyway. Unless, I'm interpreting this rule wrong.
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That is one instance that has not been clarified since they put that rule in.

I think if you have increased a 20 amp circuit to 10 AWG then you should increase the EGC to 10 AWG also - that one is maybe not so unclear, but if you have a 40 amp circuit and end up increasing conductors to 6 AWG instead of 8 AWG for "any" reason, it is not clear if the EGC needs increased also, because if you had same conductors but a 50 amp circuit - the EGC only needed to be 10 AWG in the first place. Clear as mud?
 
kwired said:
That is one instance that has not been clarified since they put that rule in.

I think if you have increased a 20 amp circuit to 10 AWG then you should increase the EGC to 10 AWG also - that one is maybe not so unclear, but if you have a 40 amp circuit and end up increasing conductors to 6 AWG instead of 8 AWG for "any" reason, it is not clear if the EGC needs increased also, because if you had same conductors but a 50 amp circuit - the EGC only needed to be 10 AWG in the first place. Clear as mud?
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It sure is! That is a good reasoning though.
 
If you use a metallic raceway approved to used for grounding, the whole thing is a moot subject. My take is if you increase /upsize the ungrounded conductor up one size, then the EGC has to be brought up one size also. If my thoughts are wrong, being set straight is a good thing.:D


Here is a link to a HI forum w/ this very subject, scroll down to post # 80, it can get long winded there..... :D:D:D:D

http://www.inspectionnews.net/home_...on-commercial-inspection/16649-wire-size.html
 
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