EGC for parallel set

[binwork91]

1. If I run (2) set DLO cable above the ground without conduit from generator to the downstream equipment, how many ground conductor do i need? 1 or 2?
2. If I run (2) set cable in one conduit (it will face derating), how many ground conductor do i need? 1 or 2?
3. if I run (2) set cable in 2 conduit, i know i need 2 ground conductor, one for each conduit.

IF all three question's answer are 2, that is good to hear. If question 1 or question 2's answer are 1. then why do we need 2 ground conductor for 2 conduit?

 

[infinity]

A single raceway would require only a single EGC even if you had multiple sets of parallel conductors within the raceway. Multiple raceways with parallel conductors require an EGC within each raceway.

 

[binwork91]

A single raceway would require only a single EGC even if you had multiple sets of parallel conductors within the raceway. Multiple raceways with parallel conductors require an EGC within each raceway.

What if multiple set without raceway? 2 set DLO cable from generator to downstream equipment.

 

[don_resqcapt19]

Note that conductors only marked "DLO" are not permitted to be used in an NEC application. Some, but not all, are dual marked with RHH or RHW and the dual marked can be used in an NEC application.

 

[binwork91]

Note that conductors only marked "DLO" are not permitted to be used in an NEC application. Some, but not all, are dual marked with RHH or RHW and the dual marked can be used in an NEC application.

see attached Cut Sheet. It is temporary for the generator.

 

[LarryFine]

The simple answer is that each conduit or other raceway is required to contain an EGC.

Moreover, each EGC in parallel raceways is required to be sized as if it was the only one.

Of course, if you're talking about metallic conduit, you don't have to use a wire EGC at all.

 

[binwork91]

The simple answer is that each conduit or raceway is required to contain an EGC.

Moreover, each EGC in parallel raceways is required to be sized as if it was the only one.

what if there is not conduit or raceway? then how many EGC we need?

 

[LarryFine]

what if there is not conduit or raceway? then how many EGC we need?

One.

 

[binwork91]

One.

Can you explain why only need one? or if you can provide the code section, that will be best.

 

[don_resqcapt19]

see attached Cut Sheet. It is temporary for the generator.

View attachment 2562844

That is not DLO....it is type W portable cable and is used in accordance with Article 400.

Note that Note D1 in Table 400.5(A)(2) applies to the conductor ampacity, and in addition, it is unlikely that the terminations on your equipment are suitable for conductors or cables used at their 90°C ampacities.

 

[LarryFine]

Can you explain why only need one? or if you can provide the code section, that will be best.

I don't have access to my NEC right now, but it's basically the same reason that one EGC can suffice for multiple feeders or branch circuits.

For paralleled conductors, it's sized for equivalent single conductor. For separate circuits, it only needs to be sized for the largest circuit.

 

[tom baker]

For parallel conductors in a pvc raceway, a full size EGC is required in each raceway as a fault can be fed from each end

 

[jap]

For parallel conductors in a pvc raceway, a full size EGC is required in each raceway as a fault can be fed from each end

What do you mean by "a fault can be fed from each end" ?

JAP>

 

[binwork91]

I don't have access to my NEC right now, but it's basically the same reason that one EGC can suffice for multiple feeders or branch circuits.

I understand this, just want to have something to support it. Can you provide the code after you can access to NEC? Thank you.

 

[don_resqcapt19]

I understand this, just want to have something to support it. Can you provide the code after you can access to NEC? Thank you.

I am not aware of any code rule that specifically addresses this issue.

 

[tom baker]

What do you mean by "a fault can be fed from each end" ?

JAP>

Draw out the parallel conductors and EGC. Trace the fault path from one set to the EGC. If one conductor shorts to the EGC, do yo see how the fault is fed from each end?

 

[infinity]

I am not aware of any code rule that specifically addresses this issue.

I couldn't think of one either. Is there a specific section that addresses free air cables?

 

[don_resqcapt19]

I couldn't think of one either. Is there a specific section that addresses free air cables?

Not that I know of...I would treat it like a cable tray installation, and use a single EGC for the setup.

 

[jap]

Draw out the parallel conductors and EGC. Trace the fault path from one set to the EGC. If one conductor shorts to the EGC, do yo see how the fault is fed from each end?

Actually I dont.

Its very uncommon for an ungrounded conductor to fault to and EGC inside a raceway for no reason.

If an EGC was not installed in one of the non-conductive raceways of a parallel feeder, it wouldn't fault to it inside the conduit to begin with and still would cause no harm.

JAP>

 

[binwork91]

Thank you all. Without a code rule that specifically addresses this issue, i think more EGC is better, to be safe.