4 CCC question

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AKElectrician

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Have a 120/208V 400 amp 3 phase service feeding a police station, would 310.15 B4(c) apply or any other commercial building that lots of computers, copy machines, fluorescent lighting, parking lot lighting, etc. Assuming they don't mean the majority of the AVAILABLE load (400 amps is overkill for this building) but the majority of the load being used, this is my interpretation of whats written. The only thing that would trump this is if the load is calculated by the linear load of all receptacles at 180VA.
 

infinity

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IMO it is not counted as a CCC. All of the 3Ø loads will be have no line to neutral connections so getting over the 50% threshold of the entire load for counting the neutral as a CCC is not going to happen.
 

AKElectrician

Senior Member
IMO it is not counted as a CCC. All of the 3Ø loads will be have no line to neutral connections so getting over the 50% threshold of the entire load for counting the neutral as a CCC is not going to happen.

well 310.154a clears up that only the unbalanced load is carried by the neutral. 310.154c says that the majority of the load, not available load, is non linear then it shall be counted. Well there should be no load on a neutral in the first place right? So IMO they mean the three hots pulling X amps, is X amps half of the 400A fuses? Or half of the actual amperage Mr. Fluke tells me? This feeds a main distribution panel feeding three 120/208V panels. IMO the majority of continuous load is fluorescents, computers, parking lot lights (Im in AK its dark a lot), all nonlinear loads. Am I reading this wrong cause I am confused. Does the Load stop at the 120/208V MDP?
 
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kwired

Electron manager
Location
NE Nebraska
well 310.154a clears up that only the unbalanced load is carried by the neutral. 310.4c says that the majority of the load, not available load, is non linear then it shall be counted. Well there should be no load on a neutral in the first place right? So IMO they mean the three hots pulling X amps, is X amps half of the 400A fuses? Or half of the actual amperage Mr. Fluke tells me? This feeds a main distribution panel feeding three 120/208V panels. IMO the majority of continuous load is fluorescents, computers, parking lot lights (Im in AK its dark a lot), all nonlinear loads. Am I reading this wrong cause I am confused. Does the Load stop at the 120/208V MDP?
You may have a lot of lights, computers, and other electronic devices but what percentage of the actual kVA are they? Good chance HVAC is more load then lights even if you only have one HVAC unit.

AFAIK about the only place where you need to be concerned with neutral harmonics and whether you should upsize the neutral or consider it a current carrying conductor is at a data center or other installation that is as packed with electronics.
 

AKElectrician

Senior Member
You may have a lot of lights, computers, and other electronic devices but what percentage of the actual kVA are they? Good chance HVAC is more load then lights even if you only have one HVAC unit.

AFAIK about the only place where you need to be concerned with neutral harmonics and whether you should upsize the neutral or consider it a current carrying conductor is at a data center or other installation that is as packed with electronics.

So a average office style computer has a desktop and 2 lcd screens the draws vary so I chose 50w a screen and 175w for the desktop 275w =.343 kVA at .8 pf just random numbers. Nothing really by itself, take 30 of them and its at 10.29kVA or 85 amps, not sure if that is considered continuous like lighting the 12,000 sq ft building takes @ 3.5 VA per square foot equals 42kVA those two loads alone are the majority of the load. Now factor in the little UPS systems that back up desktops, that may or may not be present. Am I thinking about this wrong and my math incorrect? I don't believe that the system is going to pose harmonics or that much more than the un-balanced load is on the neutral. But with todays growing use of electronics more and more, getting away from linear lighting (incandescents) and moving to CFLs LED and fluorescents. These are all non linear loads correct? If so pennies still make dollars ( I hope) and am wonder if sooner or later this will become a issue? I will also state I am a young journeyman and probably way off track and probably chasing a Gardner- Bender 6500 Wire Stretcher
 

infinity

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Location
New Jersey
Occupation
Journeyman Electrician
You may have a lot of lights, computers, and other electronic devices but what percentage of the actual kVA are they? Good chance HVAC is more load then lights even if you only have one HVAC unit.

AFAIK about the only place where you need to be concerned with neutral harmonics and whether you should upsize the neutral or consider it a current carrying conductor is at a data center or other installation that is as packed with electronics.

I agree, there aren't many occupancy's that would have a larger than 50% nonlinear component especially a police station.
 

AKElectrician

Senior Member
The whole picture is a 400A Disco was hit and made the handle unusable. Its a older Disco so not sure that the wires will fit we hope they do but since its old wiring the insulation tends to be dry and crack. Our fear is the wire being to short, or the insulation being compromised in the removal and install of the disco, have seen it happen not a good day. The line side is in a CT it is directly next to it easy to redo if need be. But to re-pull the load side is a bit more being that its 500s X 4 plus ground. So need to know if its a 4 CCC or 3 CCC for correct size. As infinity said no cause its load is a MDP no line to neutral loads. Correct?
 

Smart $

Esteemed Member
Location
Ohio
... If so pennies still make dollars ( I hope) and am wonder if sooner or later this will become a issue?
More so as each year passes.


So if the feeder neutral to the MDP is not counted because IT has no line to neutral loads, are the feeders to the sub panels where this would be counted?
So far those saying not in your case are just guessing. If the load calculation supports your suspicion, then that's what it is.
 
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