Neutral conductor requirement at a Main Disconnect

[mpwasco]

Is a grounded conductor (Neutral) required at a main disconnect from a separately derived system? i am installing a delta, wye transformer but the engineer is not requesting or wanting an ungrounded conductor at the main disconnect load center.? is required by code that a separately derived system have a neutral conductor as it is with a service?

 

[don_resqcapt19]

The neutral is not required for a SDS if there are no line to neutral loads. You will need a supply side bonding jumper between the SDS and the first means of disconnect.
You can run the wye as a ungrounded system, but if you do, you will have to add ground fault detection.

 

[mpwasco]

The neutral is not required for a SDS if there are no line to neutral loads. You will need a supply side bonding jumper between the SDS and the first means of disconnect.
You can run the wye as a ungrounded system, but if you do, you will have to add ground fault detection.

Thank you

 

[mpwasco]

The neutral is not required for a SDS if there are no line to neutral loads. You will need a supply side bonding jumper between the SDS and the first means of disconnect.
You can run the wye as a ungrounded system, but if you do, you will have to add ground fault detection.

just curious? what would the reason be to have a delta-wye transformer being used without a grounded conductor? why wouldn't you just install a delta-delta if you are never using any line to neutral loads and not bringing in a grounded conductor to the main disconnect?

 

[jim dungar]

just curious? what would the reason be to have a delta-wye transformer being used without a grounded conductor? why wouldn't you just install a delta-delta if you are never using any line to neutral loads and not bringing in a grounded conductor to the main disconnect?

You may want to limit the Line to Ground voltage. This is pretty much mandatory when there are L-G connected noise filters/capacitors in electronic equipment like VFDs.

 

[bwat]

just curious? what would the reason be to have a delta-wye transformer being used without a grounded conductor? why wouldn't you just install a delta-delta if you are never using any line to neutral loads and not bringing in a grounded conductor to the main disconnect?

Delta-wye transformers are a lot more common. So cost, availability, etc would be good reasons.

 

[infinity]

just curious? what would the reason be to have a delta-wye transformer being used without a grounded conductor? why wouldn't you just install a delta-delta if you are never using any line to neutral loads and not bringing in a grounded conductor to the main disconnect?

With a 3 wire Delta secondary you'll need to either set it up as a corner grounded system or an ungrounded system. A grounded Wye system might simply be easier.