1200a service

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fmtjfw

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Fairmont, WV, USA
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What is the neutral load according to the service calculations?
What is the service for? (Bank, hospital, pinball arcade, or really huge McMansion)
Not enough information in OP to even guess at answer.
 
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texie

Senior Member
Location
Fort Collins, Colorado
Occupation
Electrician, Contractor, Inspector
Hendrix said:
208-120vac parallel. Should the grounded conductor be the same size as the ungrounded conductors?
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The grounded conductor(s) must be sized for the load and not necessarily the same as the ungrounded conductors. But be aware that in no case can the grounded conductor(s) be smaller than indicated in Table 250.66 even if there is no load calculated load on the grounded conductor. See 250.24(C).
 
kwired

kwired

Electron manager
Location
NE Nebraska
texie said:
The grounded conductor(s) must be sized for the load and not necessarily the same as the ungrounded conductors. But be aware that in no case can the grounded conductor(s) be smaller than indicated in Table 250.66 even if there is no load calculated load on the grounded conductor. See 250.24(C).
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That is the correct response based on NEC minimum requirements. Anything beyond that is a design issue, and not a code requirement.

Not sure exactly which section it is but I think there is an informational note stating that it may be desirable to increase the grounded conductor size in cases where high harmonic currents are expectedl. This is just an informational note though and not a requirement.
 
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Lectricbota

Senior Member
Location
Rocky Mountain Region
kwired said:
Not sure exactly which section it is but I think there is an informational note stating that it may be desirable to increase the grounded conductor size in cases where high harmonic currents are expectedl. This is just an informational note though and not a requirement.
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I think kwired is referencing the informational notes pertaining to 220.61.
 
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Hendrix

Senior Member
Location
New England
texie said:
The grounded conductor(s) must be sized for the load and not necessarily the same as the ungrounded conductors. But be aware that in no case can the grounded conductor(s) be smaller than indicated in Table 250.66 even if there is no load calculated load on the grounded conductor. See 250.24(C).
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I am refering to the "grounded" conductor, not the "grounding" conductor.
 
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texie

Senior Member
Location
Fort Collins, Colorado
Occupation
Electrician, Contractor, Inspector
Hendrix said:
I am refering to the "grounded" conductor, not the "grounding" conductor.
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So am I. See 230.31(C) and 250.24(C). Your OP said service, but the requirements for a feeder would be similar except you would use Table 250.122. I know you think think I'm refering to grounding conductors but you have to remember that the grounded conductor has to carry the fault current just like an EGC.
 
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augie47

augie47

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Location
Tennessee
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State Electrical Inspector (Retired)
I believe most, if not all, the answers you were given addressed the groundED conductor.
There are correlations between the grounded and grounding conductors.
As noted in 250.24(C) we are reminded that the groundED conductor supplying a servicd can not be smaller than the groundING electrode conductor.
In 215.2 we are advised that the groundED conductor can not be smaller than the equipment groundING conductors for feeders.

Beyond that, and the minimum size parallel rule, the grounded conductor(s) can be sized be Art 220.
 
Dennis Alwon

Dennis Alwon

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Location
Chapel Hill, NC
Occupation
Retired Electrical Contractor
In most case the neutral- grounded conductor is sized the same as the ungrounded conductor in commercial work
 
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