Custom automatic transfer switching enclosure advice needed

[HertzGood85]

I work in a healthcare facility and I have been tasked to engineer and install some type of custom automatic transferring setup that can transfer 20 to 30, 20 amp 120 and 208 volt circuits as well a few 30 amp circuits.
They would have transfer automatically or manually between two separate sub feeds, one sub feed designated as Epower since it can be fed by generator or utility and the start sub feed panel being designated as normal power and being fed only by utility.

Now the best was I could think of doing this was installing multiple sets of modular lighting contacts and having one source of AC feeding the normally closed contacts and the other source feeding normally open.

In a normal state of things one set of contacts would be providing voltage to the various loads but when you energized the coils they would switch states allowing the second AC SOURCE to provide voltage to the loads. Of course I would put a delay between the state change. Anyway is this legal? I have been scouring section 700 of the nec trying to make sense of it anybody have any insight?

Thanks

 

[LarryFine]

I believe that a mechanical interlock must be implemented, not just electrical. It needs to be physically impossible to interconnect sources, even with a device malfunction.

 

[Cow]

It sounds like all these circuits should be originating from an E Panel with the ATS in front of it, that is how the health care facilities we are in are wired.

 

[ron]

Are these actually 700 or 701 loads? Actually Emergency or Legally required?

Actually even if 702 loads, the code requires the transfer to be suitable for the indented use and designated and installed so as to rpevent the inadvertant interconnection of the sources

 

[ATSman]

Besides taking on a lot of liability with life-safety circuits, why re-invent the wheel?
Install an off the shelf ATS that has the proper listings and certifications.

 

[HertzGood85]

First off thank you for your input, now to try and answer your questions.
1. Mechanical interlock, that's what I thought also but was unsure if a electronic module would do or a mechanical module would be needed as well so I ordered both for my contact blocks. I am using Eatons c30s I believe which seem to me to have the most modular ability to incorporate the amount of circuits.

2. None of these circuits are are what you would consider life safety, they are more in the realm of keeping up the operation of certain equipment that was never intended to be on the emergency standby generator because when the facility was built it wasn't designed to have these circuits on the emergency power system. The majority of these circuits are the continued operation of kitchen equipment during planned maintenance of our main feeder low voltage circuit breakers such as load tests etc. So really these circuits they want to transfer are what the admin have deemed necessary to be on two separate sources.

3. To answer two in one, yes a properly sized ATS would be the best answer to this problem with a new panel feeding all intended loads but there are obstacles such as the main electrical room where all the branch circuits originate has no room whatsoever for an accessible panel since it was never intended to or designed for installation of more panel boards etc.
I have seen some pretty good ABB BRAND ats though and I purchased some for larger circuits they want on two separate sources like a 60 amp bally unit feeding all kitchen equipment etc.

... if I had my choice I would ask them to contract this out so that a contractor would tell them it's not possible but because we are a state organization it seems I'm stuck with the design.