EG Sizing - Feeder Taps

[Design Electric Inc.]

I am looking for guidance in as far as the Grounding Conductor sizing when installed along with PH Cnductors that are tapped conductors AND per 240.12(b)(5) considered outside of building.
The TAP conductors (CU) which are are rated at 380A.
The TAPPED conductors are rated at 175A @ 75c
Am i correct in assuming that since there must be an OCD for this feeder once it enters the building that the EG sizing would be per the OCD in this
device / disconnect?

 

[Design Electric Inc.]

EG Sizing - Feeder Taps

250.122(g) is telling me the EGC for tapped feeders must NOT be sized per the OCD once it enters the building, but to size it per the TAP conductors OCD rating.

Any further comment??

 

[ibew441dc]

250.122(g) is telling me the EGC for tapped feeders must NOT be sized per the OCD once it enters the building, but to size it per the TAP conductors OCD rating.

Any further comment??

If the conductors entering the building are tapped conductors the EGC must be sized per 250.122. Although it does continue to state that the EGC does not have to be larger than the tapped conductors.

Once the tapped conductors reach a OCPD of some type, the load side of the OCPD is no longer a tap.

ibew441dc

 

[Design Electric Inc.]

Thanx IBEW

Thanx IBEW

If the conductors entering the building are tapped conductors the EGC must be sized per 250.122. Although it does continue to state that the EGC does not have to be larger than the tapped conductors.

Once the tapped conductors reach a OCPD of some type, the load side of the OCPD is no longer a tap.

ibew441dc

This was a Grey Area for me...
Thanks again!!

 

[petersonra]

If the conductors entering the building are tapped conductors the EGC must be sized per 250.122. Although it does continue to state that the EGC does not have to be larger than the tapped conductors.

Once the tapped conductors reach a OCPD of some type, the load side of the OCPD is no longer a tap.

ibew441dc

So the answer is the - the EGC for a tap conductor has to be the same size as the tap conductors until you reach the tap OCPD, at whcih point it can be sized normally.

 

[don_resqcapt19]

So the answer is the - the EGC for a tap conductor has to be the same size as the tap conductors until you reach the tap OCPD, at whcih point it can be sized normally.

No the EGC for the tap circuit is sized based on Table 250.122 and the rating of the OCPD that supplies the tap conductors.
Don

 

[petersonra]

No the EGC for the tap circuit is sized based on Table 250.122 and the rating of the OCPD that supplies the tap conductors.
Don

(G) Feeder Taps. Equipment bonding conductors run with
feeder taps shall not be smaller than shown in Table
250.122 based on the rating of the overcurrent device ahead
of the feeder but shall not be required to be larger than the
tap conductors.

It appears to me it says they don't have to be any larger than the tap conductors. I don't have a copy of 2005 but that is what is in the draft.

 

[infinity]

It appears to me it says they don't have to be any larger than the tap conductors. I don't have a copy of 2005 but that is what is in the draft.

If you used the 10 foot tap rule and had a tap conductor with an ampacity of 10% of the feeder OCPD, would that same sized EGC be large enough to open the OCPD during a fault condition?

 

[petersonra]

If you used the 10 foot tap rule and had a tap conductor with an ampacity of 10% of the feeder OCPD, would that same sized EGC be large enough to open the OCPD during a fault condition?

good question. i would guess the answer is yes since you are only talking about ten feet and it would be the same size as the tap conductors. the tap conductors are part of the same ground fault path.

 

[don_resqcapt19]

Bob,

It appears to me it says they don't have to be any larger than the tap conductors.

Correct the EGC does not have to be larger than the circuit conductors, but the post that I was commenting on said that the EGC has to be the same size as the tap conductors. There are many cases where that is not true.
Don