Tulsa Electrician
Senior Member
- Location
- Tulsa
- Occupation
- Electrician
EGC
- Thread starter Alwayslearningelec
- Start date
- Status
- Location
- New Jersey
- Occupation
- Journeyman Electrician
Unfortunately the OP is under the 2008 NEC.
ramsy
NoFixNoPay Electric
- Location
- LA basin, CA
- Occupation
- Service Electrician 2020 NEC
OP profile says New Jersey, which adopted the 2000 NFPA-70 on 9/6/2022
That exception requires a qualified PE licence under engineering supervision, with questionable benefit.
However, same 2020 NEC changes remove upsizing EGC for any reason except voltage drop.
Did not see that stated here, but #600 would work, even with 310.15(B)(5)(c) counting 4 ccc's
I like horsegoer's original idea to submit an RFI for using metallic raceway for EGC, per 250.96-102. Even though 2/0 bonding jumpers might get ugly.
Tulsa Electrician
Senior Member
- Location
- Tulsa
- Occupation
- Electrician
Was not swear of them being in 2008. Not sure I even have that one.
As far as the EMT as the EGC. I will review my book on the use of EMT and it foot limitation as an effective ground fault path.
Thank you all for your responses on the 2020 exception.
As far as the EMT as the EGC. I will review my book on the use of EMT and it foot limitation as an effective ground fault path.
Thank you all for your responses on the 2020 exception.
Alwayslearningelec
Senior Member
- Location
- NJ
- Occupation
- Estimator
This would be a good subject to get a 100% definitive answer to which is correct.
- Location
- Illinois
- Occupation
- retired electrician
CMP-5's opinion is that the phase conductor for parallel sets is the sum of the areas of all of the conductors that are connected in parallel, so the EGC for a single set of parallel conductors may be larger than the ungrounded conductors in each raceway.
- Location
- Illinois
- Occupation
- retired electrician
The exception only says "qualified person" and does not say engineering supervision. This becomes a judgement call on the part of the AHJ. There are a number of electrical engineering software programs out there that can do this calculation and there is no need for a PE to input numbers into a software program.
- Location
- New Jersey
- Occupation
- Journeyman Electrician
I agree. I have seen feeders with EGC's larger than the ungrounded conductors.
kwired
Electron manager
- Location
- NE Nebraska
- Occupation
- EC
And it usually will happen once you get past 3 or 4 parallel sets in the run.
3 sets of 500 kcmil in parallel is effectively 1500 kcmil. There is no allowance for paralleling EGC's to effectively make a larger conductor, or wasn't before 2020 NEC anyway that I have ever been aware of.
At same time OP would be compliant to use the metal raceway as the EGC, and will save just a little copper doing so.
wwhitney
Senior Member
- Location
- Berkeley, CA
- Occupation
- Retired
I'm not seeing that prohibition in 2017, 2020, or 2023.
(2017) 250.122(F)(1)(a) (parallel conductor installation in a single raceway or cable) does refer to "a single wiretype" EGC, which I guess rules out paralleling EGCs in that scenario. But 250.122(F)(1)(b) (multiple raceways) doesn't. And 310.10(H)(2) refers explicitly to parallel EGCs. The absence of EGCs in the list in 310.10(H)(1) just means that parallel EGCs are not subject to a 1/0 minimum size (which is a good thing, as branch circuit EGCs often end up in parallel).
Cheers, Wayne
- Location
- Illinois
- Occupation
- retired electrician
Yet if those conductors were transformer secondary conductors, I would install a supply side bonding jumper in each raceway sized per Table 250.102(C)(1) and would have a 1/0 SSBJ in each raceway. For any place you use a supply side bonding jumper, you would never have the bonding jumper larger than the ungrounded conductors in any raceway.
kwired
Electron manager
- Location
- NE Nebraska
- Occupation
- EC
regardless of what code might say I agree it makes no sense to require a grounding or bonding conductor larger then the largest ungrounded conductor in a raceway.
- Location
- New Jersey
- Occupation
- Journeyman Electrician
Why is that? If the parallel conductors are #1/0 and the required EGC is 250 kcmil then it would be okay to undersize the EGC.and use a #1/0?
kwired
Electron manager
- Location
- NE Nebraska
- Occupation
- EC
If the sets are in separate raceways why not? A fault in the raceway is not carrying any more current than the 1/0 ungrounded conductor can deliver. If the paralleled 1/0 are all in the same raceway then I believe the 250 EGC would be needed.
ptonsparky
Tom
- Occupation
- EC - retired
But it is. The fault is being feed from both ends of that 1/0 because of its parallel connection to the rest of that phase.
LarryFine
Master Electrician Electric Contractor Richmond VA
- Location
- Henrico County, VA
- Occupation
- Electrical Contractor
From what we have discussed here many times, a correctly-assembled EMT system has better fault-current performance than the EGC that would otherwise accompany the conductors the EMT could contain.
- Location
- Illinois
- Occupation
- retired electrician
In my opinion, yes because that is still larger than what would be required for a supply side bonding jumper with parallel sets of conductors.
If you had parallel 1/0s in separate raceways where a supply side bonding jumper is used and not an EGC, the supply side bonding jumper would only be 6 AWG in each raceway. It is my opinion that locations where supply side bonding jumpers are used are a worse case as far as fault clearing as compared to where EGCs are used.
- Location
- New Jersey
- Occupation
- Journeyman Electrician
In the case of the EGC it's required to be larger than the ungrounded parallel conductors when situations like the one in this thread is encountered. I agree with you that when using a SSBJ the conductor is typically smaller than the a similarly required EGC which makes no sense. Until the NEC comes up with a better rule for EGC's we're stuck with what we have.
Tulsa Electrician
Senior Member
- Location
- Tulsa
- Occupation
- Electrician
Thank you for letting me know.
- Status