neutral size for 100a residential service
- Thread starter mannyb
- Start date
- Status
- Location
- New Jersey
- Occupation
- Journeyman Electrician
You would still need to calculate the neutral current according to Article 220, then you use the minimum in 250.24(C) if that size is large enough for the calculated conductor size.
I Understand. We have a couple services that will just control a well pump on side of road in the county and not really any neutral load. We started talking about it and the question came up about residential also
kwired
Electron manager
- Location
- NE Nebraska
Check with your AHJ but many won't make you show calculations if you are no more than two sizes smaller than the ungrounded conductors, if it is only carrying unbalanced current and not a single phase three wire derived from a wye source where the neutral would typically carry same amount of current as the two ungrounded if it were all line to neutral loads but otherwise balanced.
If a majority of your load were 240 volt loads you may not have that much neutral current even possible, but in no case can the service neutral be smaller than the required grounding electrode conductor for the application.
If a majority of your load were 240 volt loads you may not have that much neutral current even possible, but in no case can the service neutral be smaller than the required grounding electrode conductor for the application.
FionaZuppa
Senior Member
- Location
- AZ
- Occupation
- Part Time Electrician (semi retired, old) - EE retired.
If it's a 2wire with EGC, then why are you entertaining using a neutral? What do you mean by "not really any neutral load"? It has N load, or it doesn't. Are you talking about 50ft 100ft or 10,000ft of wire for the N (if needed at all)? 100ft or less, just size it the same as the L1L2 wire and call it a day, county will pay it. This also leaves it for a future state where if a full sized N is needed, it's already there.
curt swartz
Electrical Contractor - San Jose, CA
- Location
- San Jose, CA
- Occupation
- Electrical Contractor
What does 310.15(B)(7) have to do with services to pumps?
kwired
Electron manager
- Location
- NE Nebraska
The service still will have a "grounded conductor". The branch circuit would not need to have a grounded conductor at all if load doesn't utilize one.
- Location
- New Jersey
- Occupation
- Journeyman Electrician
It says it right in the title of the this thread he's asking about a neutral for a service.
ptonsparky
Tom
- Occupation
- EC - retired
We really don't care if the neutral has a load today, as long as it's there and sixed to carry the fault current when it is needed.
FionaZuppa
Senior Member
- Location
- AZ
- Occupation
- Part Time Electrician (semi retired, old) - EE retired.
That's to the service box, so yes. Perhaps I misunderstood the OP's ask. Post #3 was a bit confusing, thought it was a N wire to pump Q. But since the SEC disco box must be in close proximity to the util, does it really matter a few cents to use full size N wire?
Post #3 mention "services" to "a" roadside well pump. I not really sure what that means.
Anyways, for fault clearing purposes & future use, why even undersize N wire to a Service-equip disco box? Just make it the same as the non-grounded CCC's.
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