Does 250.122(B) mean you only have to increase the egc if there is voltage drop? This is 2014 Nec change.
Does 250.122(B) mean you only have to increase the egc if there is voltage drop? This is 2014 Nec change.
That article has been there for a long time they just added some wording to help where you start from.
250. 122 (B) means anytime you increase the size of your ungrounded conductors then you must increase the equipment grounding conductor proportionally no matter what the reason for the increase in conductor size may be
It can be and is.It cannot be for any and every reason, the extra language has changed that.
As noted in my other post, you base it on conductor size without changing wiring method or other conductor characteristics.In the case of parallel sets, it gets a little more interesting. How does one determine what counts as ?the minimum size that has sufficient ampacity for the intended installation??
Example: A 400A feeder with 320A continuous load, that you upsize from 1 set of 600 to 2 sets of 400 in separate conduits. Or did I upsize it from 2 sets of #3/0 to 2 sets of 400?
It can be and is.
However, you and Dennis are exhibiting different premises of determination.
Here's how to look at it...
If Code permits you to use a smaller conductor, without changing wiring method or other conductor characteristics, your conductor is "increased in size".
While I agree that is what Code requires, think about the justification for other than voltage drop considerations. Using your example, if you place that #6 circuit on a 60A breaker, you'd only need a #10 EGC... but you put it on a 20A breaker and you now need a #6 EGC. That contradicts all logic and the physics behind conductor protection.....
The misconception would be that a #10 EGC is misinterpreted as being required as a #6 would normally be put on a 60 amp overcurrent device, improperly sizing the EGC to the normal overcurrent protection device (OCPD) for the #6 circuit conductor being placed on a 20 amp OCPD.
What does not get understood, is that you have to have the conductor sized properly to get the current back to the source so as to get the OCPD to operate properly during a fault event. If the return is too small, it will be more of a load than a fault, thusly, not allowing the OCPD to operate properly.
....
As noted in my other post, you base it on conductor size without changing wiring method or other conductor characteristics.
In the example used, you base the increase in size to 2 sets of 400kcmil on the smallest permitted by Code using 2 sets, which is 3/0 barring other conditions of use not mentioned.
You mean 4 sets of #3 is the basic size for 400A.It would be interesting to see how this applies to an installation of parallel sets, whereby when you calculate the minimum local size at that number of parallel sets ends up being smaller than #1/0.
For instance, a 400A feeder upsized to 4 sets of 300 kcmil. We're talking about a REALLY long feeder, here. In this example, 400A at 4 sets = #2. Four sets of #2 theoretically has the ampacity of 400A, but isn't permitted by the NEC. I suppose the "floor" of your starting point would be "N sets of 1/0", where N is the number of parallel sets in your installation.