Installing a 13.8kv to 480Y/277 transformer, the neutral on the secondary is not needed and was planning to ground the neutral at the transformer. Was only going to pull L1, L2, L3 and ground from the transformer to 480v, 3-wire switchboard. Was told according to Article 250.24(C) I have to bring the neutral in and ground it. I don't believe this to be correct can anyone confirm?
Delta to Wye Transformer Grounded Neutral
- Thread starter dcheser
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zbang
Senior Member
- Location
- Roughly 5346 miles from Earls Court
Just to confirm, this is a SDS and not a service?
I would otherwise you would have a floating neutral.
13.8kV Utility feed to pad mount transformer primary, 480V to main switchgear. switchgear is 3-phase, 3-wire and the neutral would be grounded at the transformer.
If Neutral is grounded at the transformer how is it floating?
My apologies - I missed that.
- Location
- Illinois
- Occupation
- retired electrician
Is the service point on the primary or secondary of that transformer? If it is on the secondary than you are required to bring the neutral to the service equipment.
- Location
- Bremerton, Washington
- Occupation
- Master Electrician
Typically for a utility service, where its secondary metered, 3 phase, you would run 3 ungrounded and the neutral to the main disconnect and install the SBJ there. If you bond the neutral at the transformer, how will fault current return to the transformer in a line to case fault? You did not mention an EGC from transformer to service.
Transformer is customer owned so service point and metering is on the primary side of the transformer
electrofelon
Senior Member
- Location
- Cherry Valley NY, Seattle, WA
Then your original plan is correct. the 250.24 reference is incorrect because that is for services. See 250.30.
electrofelon
Senior Member
- Location
- Cherry Valley NY, Seattle, WA
Just a thought: If 250.30(A)(1) exception 2 applies (allows bonding on both ends, bond the switchboard to neutral like a service), you can run a neutral instead of an SSBJ to the switchboard, then you will have a neutral there if by chance you ever need it.
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