wye neutral conductor
- Thread starter jjavier
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- Placerville, CA, USA
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- Retired PV System Designer
If the inverter does not source any current to the neutral, only from line to line, you can reduce the size of the neutral.
But if, for example, you have three independent L to N inverters you cannot assume that the neutral current will always sum to zero.
mobile
But if, for example, you have three independent L to N inverters you cannot assume that the neutral current will always sum to zero.
mobile
ron
Senior Member
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- New York, 40.7514,-73.9925
This article is dated, but has similar sizing to current NEC versions
http://ecmweb.com/code-basics/characteristics-neutral-conductor
http://ecmweb.com/code-basics/characteristics-neutral-conductor
jaggedben
Senior Member
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- Northern California
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- Solar and Energy Storage Installer
Very likely the neutral can be sized the same as the EGC, but you'll have to get the manufacturer to verify either that the neutral is for sensing only (705.95(B)) or that the calculated load is less than the EGC size is rated for.
ggunn
PE (Electrical), NABCEP certified
- Location
- Austin, TX, USA
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- Consulting Electrical Engineer - Photovoltaic Systems
You also should check with your AHJ. Here in Austin, for example, irrespective of how the inverter uses the neutral it is required to run a full sized neutral from the service through the dedicated PV meter at least to the next terminal point.
You can’t go wrong with a full sized neutral, but there are allowances in the NEC for reduced size neutrals. The one most often used for inverters is when the neutral is only used to sense line to neutral voltage for the anti-islanding system, and then the neutral can be sth same size as the EGC.
Unfortunately I have rarely found in the manufacturer’s documentation anything stating the neutral is for sensing only or can be reduced, the terminals in the inverter usually allow a full sized neutral which can be used as an indication that the manufacturer is expecting it, and getting the answer from a support person on the phone may or may not be enough for an AHJ if they question it.
Unfortunately I have rarely found in the manufacturer’s documentation anything stating the neutral is for sensing only or can be reduced, the terminals in the inverter usually allow a full sized neutral which can be used as an indication that the manufacturer is expecting it, and getting the answer from a support person on the phone may or may not be enough for an AHJ if they question it.
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