Egc sizing

[Djelite]

No, since service conductors normally are not accompanied by EGCsssbj

 

[kwired]

Just my take on it anyway. May be all wet and need more schooling. An engineer may help with this question
Quick withstand rating on #6 and 1/0 @ 1/2 cycle
#6 =15,213 amps
1/0=61,223
Which one you want in that pipe with a let though of 42K

you won't see 42k unless maybe the fault occurs very close to the source end of the run, the conductor resistance will be current limiting. At same time the more current you can get to flow the faster the OCPD might operate

 

[kwired]

And the ocpd is sized to the conductors. So the sizing issue still applies, correct?

discussion has been about whether we should be able to reduce EGC's in parallel runs, basically in same fashion as you add up the cross section of the current carrying conductors in parallel to effectively create one larger conductor. The issue with the EGC is if there is a fault in one conduit of a parallel set it has to be able to carry enough fault current to trip the OCPD in reasonable time and without significant damage to itself at very least before the circuit is opened by the OCPD. An example was four sets of 3/0 in parallel - presuming for an 800 amp circuit. The same 3/0 as a single conductor can have a 6 AWG grounding conductor run with them, but now put them in parallel on said 800 amp circuit (in four separate raceways) and fault one the ungrounded to the 6 AWG in one raceway - you are asking that #6 to carry fault current necessary to trip the 800 amp device, when normally a 1/0 conductor would be necessary for an 800 amp OCPD.

multiple #6 in parallel possibly is sufficient to get the job done if the fault were to be say in whatever was at the far end of the parallel set where they come together - at that point they have effectively created a larger conductor back to the source.

 

[Djelite]

discussion has been about whether we should be able to reduce EGC's in parallel runs, basically in same fashion as you add up the cross section of the current carrying conductors in parallel to effectively create one larger conductor. The issue with the EGC is if there is a fault in one conduit of a parallel set it has to be able to carry enough fault current to trip the OCPD in reasonable time and without significant damage to itself at very least before the circuit is opened by the OCPD. An example was four sets of 3/0 in parallel - presuming for an 800 amp circuit. The same 3/0 as a single conductor can have a 6 AWG grounding conductor run with them, but now put them in parallel on said 800 amp circuit (in four separate raceways) and fault one the ungrounded to the 6 AWG in one raceway - you are asking that #6 to carry fault current necessary to trip the 800 amp device, when normally a 1/0 conductor would be necessary for an 800 amp OCPD.

multiple #6 in parallel possibly is sufficient to get the job done if the fault were to be say in whatever was at the far end of the parallel set where they come together - at that point they have effectively created a larger conductor back to the source.

If this is your issue then this rule be diviided into 2 sections based on rating

 

[kwired]

btw

I've always noticed that but never thought about why not?

on supply side and including the service disconnect enclosure, all non current carrying conductive components are bonded to the grounded conductor. Running an additional "EGC" would simply put it in parallel with the grounded conductor, and if it were reduced size like it typically is on the load side of the service disconnect, it could possibly be carrying quite a bit of the grounded conductor current in relation to its physical size and would possible overheat.

An EGC is not intended to carry current at all other than during a fault condition.

 

[Djelite]

on supply side and including the service disconnect enclosure, all non current carrying conductive components are bonded to the grounded conductor. Running an additional "EGC" would simply put it in parallel with the grounded conductor, and if it were reduced size like it typically is on the load side of the service disconnect, it could possibly be carrying quite a bit of the grounded conductor current in relation to its physical size and would possible overheat.

An EGC is not intended to carry current at all other than during a fault conditiono one said anything

on supply side and including the service disconnect enclosure, all non current carrying conductive components are bonded to the grounded conductor. Running an additional "EGC" would simply put it in parallel with the grounded conductor, and if it were reduced size like it typically is on the load side of the service disconnect, it could possibly be carrying quite a bit of the grounded conductor current in relation to its physical size and would possible overheat.

An EGC is not intended to carry current at all other than during a fault condition.

The discussion is not about egc on

on supply side and including the service disconnect enclosure, all non current carrying conductive components are bonded to the grounded conductor. Running an additional "EGC" would simply put it in parallel with the grounded conductor, and if it were reduced size like it typically is on the load side of the service disconnect, it could possibly be carrying quite a bit of the grounded conductor current in relation to its physical size and would possible overheat.

An EGC is not intended to carry current at all other than during a fault condition.

we are not taking about egc with service. Its about proper sizing of both bonding jumpers and egs that believe need a little tweeting

 

[kwired]

The discussion is not about egc on

we are not taking about egc with service. Its about proper sizing of both bonding jumpers and egs that believe need a little tweeting

I know, I was replying to a question why there isn't EGC's on service side.