Missing neutral question

[kwired]

This is why I ussually suggest running a neutral even if planned loads will not require one, eventually soneone wants to add something that does.
OP, is conduit large enough to pull in a neutral? Might be easier than trying some creative way to sidestep the required neutral. In this circumstance I see this particular meter as just another device requiring a neutral. Is there a different meter not requiring a neutral?

For 120/208-240 feeders probably not bad idea. For 480 volts - I seen many feeders with no neutral as all that was supplied was 480 volt loads. Not much for common 277 volt loads other than lighting to potentially be added where 120 volt loads of many kinds are pretty common.

 

[kwired]

That makes no sense to me. The CCCs are split, why not the neutral? It's not like an ECG that needs to be able to clear the fault for the whole rating of the OCPD.

For feeders it says you must have that minimum size, for branch circuits I think you could run smaller grounded conductor, though some here haven't agreed with me on that in the past. For parallel conductors you usually need same conductors in each raceway to achieve same overall impedance in each raceway so current will balance properly across the parallel conductor sets.

 

[kwired]

There is no neutral load, really; it's just for instrumentation.

Any three identical impedance 277 volt loads connected in a wye configuration would do the same thing.

 

[wwhitney]

So what does a self-contained 480V Delta meter look like? Vs a self-contained 480Y/277V Wye meter? Does the latter really have internal electronics that depend on the presence of the neutral?

Cheers, Wayne

 

[kwired]

Which goes back to the fact that the only reason this neutral is 'needed' is because the wrong meter is being required by some authority for the job.

I feel for you.

Jon

The right meter may or may not have similar arrangement within it (small autotransformer to derive a neutral) to get the job done.

 

[electrofelon]

There is no neutral load, really; it's just for instrumentation.

right which makes me wonder if you could just run say a 20A #12AWG branch circuit for the instrumentation rather than a feeder neutral.

 

[kwired]

right which makes me wonder if you could just run say a 20A #12AWG branch circuit for the instrumentation rather than a feeder neutral.

For a CT meter probably so. For self contained meter any such instrumentation is already on board the unit.

 

[electrofelon]

For a CT meter probably so. For self contained meter any such instrumentation is already on board the unit.

Ok but is there a code that says I can't run a #12 white wire for/to that jaw of the meter?

 

[kwired]

Ok but is there a code that says I can't run a #12 white wire for/to that jaw of the meter?

For the 20 amp branch circuit you mentioned I sure hope not.

For self contained meter that goes in line with a feeder, I myself have no issue with it but I suppose NEC still wants their minimum size for a feeder neutral which will need to be same size as minimum required EGC.

 

[electrofelon]

but I suppose NEC still wants their minimum size for a feeder neutral which will need to be same size as minimum required EGC.

Code reference?

 

[wwhitney]

Code reference?

(2017) 215.2(A)(2)

Cheers, Wayne

 

[electrofelon]

(2017) 215.2(A)(2)

Cheers, Wayne

My thought is you could call it something other than a feeder conductor. I don't see that conductor carrying any current or really being part of the feeder. I suppose there is a high impedance voltage measuring circuit across the neutral and the ungrounded conductors however.

 

[wwhitney]

My thought is you could call it something other than a feeder conductor.

What exactly? It's not a branch circuit, and it's not a service conductor, and it's in between those, so it's a feeder.

Do you have info on my questions in post 44? Is there such a thing as a self-contained meter for a 480V 3 phase 3-wire Delta?

Thanks,
Wayne

 

[ggunn]

(2017) 215.2(A)(2)

Cheers, Wayne

For PV under the 202 NEC it's 705.28(C)(2), which points to 250.102, which is the sizing of a bonding jumper.

 

[electrofelon]

What exactly? It's not a branch circuit, and it's not a service conductor, and it's in between those, so it's a feeder.

Do you have info on my questions in post 44? Is there such a thing as a self-contained meter for a 480V 3 phase 3-wire Delta?

Thanks,
Wayne

It seems it could fit the definition of branch circuit to me. I guess maybe its a stretch if the other voltage reference wires are coming from the feeder itself and not a separate branch circuit like you could do if it was an instrument meter.

Regarding the meter question I ama not sure. I have seen a 600V ungrounded delta meter (not self contained) and it utilized the two-watthour method, but I am unsure why a neutral is needed for wye metering.

 

[wwhitney]

It seems it could fit the definition of branch circuit to me.

If the meter is utilization equipment, sure, but is it? Seems like it's not.

Regardless, ggunn's 705.28(C)(2) reference likely controls in this case.

Cheers, Wayne

 

[petersonra]

I think it is more of a measuring circuit so something like maybe a class one circuit

 

[jaggedben]

I've wondered before if meter instrumentation conductors such as CT leads are article 725 conductors and if so how they are classified, and not found a clear answer.

That said, it's not clear to me that this idea helps out ggunn as he is looking for something to avoid trenching or presumably pulling anything through the existing conduit.

 

[electrofelon]

I've wondered before if meter instrumentation conductors such as CT leads are article 725 conductors and if so how they are classified, and not found a clear answer.

That said, it's not clear to me that this idea helps out ggunn as he is looking for something to avoid trenching or presumably pulling anything through the existing conduit.

some opinions here, but nothing definite https://forums.mikeholt.com/threads/ct-wiring-classification.106402/


Another long shot idea: I wonder if the AHJ and POCO would allow the EGC to be used for the neutral reference? I know some inverter manufacturers say you can to this (solectria and chint IIRC).

 

[electrofelon]

I've wondered before if meter instrumentation conductors such as CT leads are article 725 conductors and if so how they are classified, and not found a clear answer.

That said, it's not clear to me that this idea helps out ggunn as he is looking for something to avoid trenching or presumably pulling anything through the existing conduit.

some opinions here, but nothing definite https://forums.mikeholt.com/threads/ct-wiring-classification.106402/


Another long shot idea: I wonder if the AHJ and POCO would allow the EGC to be used for the neutral reference? I know some inverter manufacturers say you can to this (solectria and chint IIRC).