Switch Neutral for ATS with UPS

[NEC User]

For an IT Equipment Room with UPS devices, should I use an Switched Neutral Bypass Isolation Switch that switches the neutral?

 

[kikeblackberry]

Using multiple power sources imposes special requirements on grounding design. First, you must determine if sources are separately derived or service supplied.

Maybe these threads will help:
http://forums.mikeholt.com/showthread.php?t=120637

http://forums.mikeholt.com/showthread.php?t=80516

 

[NEC User]

The sources are separately derived.

 

[Smart $]

It's relatively simple to make the determination....

If you do not switch the neutral, will the other source and/or the grounding system be a parallel path for neutral current? If yes, the neutral is required to be switched.

 

[ron]

This is a good presentation regarding 3 pole or 4 pole. http://www.russelectric.com/wp-content/uploads/3_or_4_pole.ppt

The definition of an SDS is related to a four pole transfer being present.

http://ecmweb.com/content/switching-neutral-whats-controversy