200% rated neutral question

[dabatman]

I have system which is requesting a 200% neutral rated panelboard that is feeding some switching power supplies. My question stems from how far back upstream does the neutral need to be rated 200%.

The general setup is a 480V-208V 3ph stepdown transformer. There will be a 208V-3ph 600A panel which has a mixture of continuous and non-continuous feeds. Out of that I will be feeding a 200A panel which has 125A non-continuous switching power supplies which is being specified to have a 200% rated neutral. Does the neutral only have to be rated for 200% back to my original 600A panel or is it all the way back to the transformer? Am I mistaken to think that the 600A neutral would be 200% rated when referring to the 200A panel? Any suggestions on places to research would be appreciated.

 

[Sierrasparky]

I would up size the nuetral to the main panel at least in the percentage of the 200 A subs load is on the 600 amp or 1/3. I am not a engineer but used to wire data centers and use panels with 200% nuetrals.

 

[Electric-Light]

Make sure the transformer is K-rated if a significant percentage of loads are harmonic producing.
Which K rating to pick can be found here:
http://www.centralyacht.com/library/electrics/kratedtransformer.pdf

There are also harmonic canceling type transformers. I'm not endorsing this particular brand, though I do find it interesting.
http://www.hammondpowersolutions.com/upload_files/hpsi-ta8.pdf

If the data center equipment mostly use power factor corrected power supplies, (>95% PF and usually <20% THD) neutral over sizing or K-rated trannies are not needed.

 

[ohmhead]

I have system which is requesting a 200% neutral rated panelboard that is feeding some switching power supplies. My question stems from how far back upstream does the neutral need to be rated 200%.

The general setup is a 480V-208V 3ph stepdown transformer. There will be a 208V-3ph 600A panel which has a mixture of continuous and non-continuous feeds. Out of that I will be feeding a 200A panel which has 125A non-continuous switching power supplies which is being specified to have a 200% rated neutral. Does the neutral only have to be rated for 200% back to my original 600A panel or is it all the way back to the transformer? Am I mistaken to think that the 600A neutral would be 200% rated when referring to the 200A panel? Any suggestions on places to research would be appreciated.

Well from what you just stated they are saying the 200 amp panel only so i guess your engineer wants two neutrals to that panel what ever wire size he picked . The 600 amp panel stays put no change .

What does you oneline show post it ?