EGC size increase due to voltage drop

[ANTONY]

The EGC was not increased in size per 250.122B when the feeder conductors were increased due to voltage drop. The feeder and undersized EGC have already been installed. Can a properly sized EGC be run in a separate conduit following the same path as the feeder conduit.

 

[augie47]

More than likely not.
Take a look at 300.3(B)(2).
What type conduit is being used ?

 

[charlie b]

Any chance you can use a higher rated overcurrent device, one that more closely matches the ampacity of the (increased) ungrounded conductors? That has a chance of allowing the (presently installed) EGC to be the right size.

 

[DARUSA]

Any chance you can use a higher rated overcurrent device, one that more closely matches the ampacity of the (increased) ungrounded conductors? That has a chance of allowing the (presently installed) EGC to be the right size.

The EGC is undersized how this can help?

 

[charlie b]

The EGC is undersized how this can help?

The only reason the EGC is undersized is that it was initially (and correctly) sized for the OCPD, then a choice was made to increase the size of the ungrounded (phase) conductors, which brought 250.122(B) into play. The EGC is undersized for the upsized phase conductors. But those conductors can support a higher rated OCPD, which might possibly call for the same size EGC as was originally installed. In this case, the phase conductors will not have to be declared to have been “increased in size,” and possibly the EGC will work as is.

Example:
? Calculated load = 120 amps.
? Selected conductor size = #1 copper (ampacity 130).
? Selected OCPD rating = 125 amps.
? Corresponding EGC size = #6 copper.
? Now someone raises the concern over voltage drop. It is decided to increase the phase conductor to #2/0 (ampacity 175).
? The EGC is required to be increased in size in proportion to the increase from #1 to #2/0 (I won’t do the math, since it doesn’t matter to my example). But they didn’t change the EGC.
? The wires actually pulled are #2/0 for the phase conductors and #6 for the EGC.
? At present, you have a violation of 250.122(B).
? Proposed corrective action: Change the OCPD from 125 amps to 175 amps.
? You now have a match between the ampacity of the conductors and the rating of the OCPD. Therefore, the phase conductors are not “increased in size.” Therefore, the correct EGC is the one that corresponds to the 175 amp OCPD. That is the same #6 that was originally pulled.
? QED.

This will not work in all circumstances. For example, if the feeder in question is supplying a panelboard that is rated for 125 amps, then you cannot use a 175 amp OCPD at the origin of that feeder.

 

[Dennis Alwon]

The problem could be that the feeders may have been upsized but the egc is still the same size as the original install required. For example, a #6 is needed for 60 maps and a #10 EGC is required. Now suppose they up size the feeder conductors to #2 but the egc remained at #10. Now install anything larger than a 60 amp breaker will require a #8 EGC minimum.

In this case it may not help to up size the OCPD, but in other cases Charlie is spot on.

 

[augie47]

The only reason the EGC is undersized is that it was initially (and correctly) sized for the OCPD, then a choice was made to increase the size of the ungrounded (phase) conductors, which brought 250.122(B) into play. The EGC is undersized for the upsized phase conductors. But those conductors can support a higher rated OCPD, which might possibly call for the same size EGC as was originally installed. In this case, the phase conductors will not have to be declared to have been ?increased in size,? and possibly the EGC will work as is.

Example:
? Calculated load = 120 amps.
? Selected conductor size = #1 copper (ampacity 130).
? Selected OCPD rating = 125 amps.
? Corresponding EGC size = #6 copper.
? Now someone raises the concern over voltage drop. It is decided to increase the phase conductor to #2/0 (ampacity 175).
? The EGC is required to be increased in size in proportion to the increase from #1 to #2/0 (I won?t do the math, since it doesn?t matter to my example). But they didn?t change the EGC.
? The wires actually pulled are #2/0 for the phase conductors and #6 for the EGC.
? At present, you have a violation of 250.122(B).
? Proposed corrective action: Change the OCPD from 125 amps to 175 amps.
? You now have a match between the ampacity of the conductors and the rating of the OCPD. Therefore, the phase conductors are not ?increased in size.? Therefore, the correct EGC is the one that corresponds to the 175 amp OCPD. That is the same #6 that was originally pulled.
? QED.

This will not work in all circumstances. For example, if the feeder in question is supplying a panelboard that is rated for 125 amps, then you cannot use a 175 amp OCPD at the origin of that feeder.

Wow! That kinda shoots the whole "increase for voltage drop requires increasing equipment ground" requirement in the foot .
It becomes, increase for voltage drop..increase breaker to match, then " forget " you increased for voltage drop

 

[Cow]

Wow! That kinda shoots the whole "increase for voltage drop requires increasing equipment ground" requirement in the foot .
It becomes, increase for voltage drop..increase breaker to match, then " forget " you increased for voltage drop

We've had to upsize the OCPD before, when someone mistakenly upsized the ungrounded conductors but didn't do the same for the EGC.

 

[Dennis Alwon]

Wow! That kinda shoots the whole "increase for voltage drop requires increasing equipment ground" requirement in the foot .
It becomes, increase for voltage drop..increase breaker to match, then " forget " you increased for voltage drop

About 2 years ago I had a very similar post because I couldn't understand why changing the breaker would make a difference--- but it is compliant.