I am working on a project where an emergency standby gen set is used for the backup power. The transfer switch that was furnished was a 3 pole unit. The customer requested a neutral conductor block for the switch. After the block was received the customer decided that they needed a 4 pole switch that would allow switching the neutral. That started me on a search as to when to switch the neurtal and how the neutral was to be grounded. This has been quite an adventure. I ran into this site on my search and picked up some useful information so I decided to post a question here. And the question is when do you switch the neutral on a transfer switch and what are the pros and cons of neutral switching?

davemacx

Moved to electricial and lighting to allow for more answers

Not switching the neutral could be advantageous as when all poles open, they all may not? Open at exactly the same time, particularly if it was switched slow or held.(open neutral condition)
Possible backfeeding may be an advantage to opening neutral. My opinion?