Automatic Transfer Switch

[hugop973]

Hi,
I have a question about an automatic transfer switch, 3000A rated with bypass. Can you tapped an additional load off the load terminal of an automatic transfer switch? Is that legal? Thanks

 

[dpc]

Maybe. See tap rule. NEC Article 240.21. This will be somewhat dependent on the actual installation. I wouldn't do it on a 3000 A switch, but that's just me.



David Castor

http://www.cvoes.com

 

[rbulsara]

I did not look up specific NEC codes, (not sure what codes apply to you), but generally it is considered non-compliant or at least a bad practice, depending up on how it is done.

May be you also want to look up NEC 312 (if applicable to you) for cabinets and cutout boxes. One of the aspects would be to ensure adequate wiring space per code. Voiding listing such as UL may also be an issue, unless the enclosure is sized accordingly. It is also a bad workmanship, if the lugs and space is no designed for the tap. NEC requires arranging for auxiliary gutters to create adequate wiring space if needed.

I also believe, NFPA specifically prohibits using ATS as a junction box, for fire pump applications. That may be one of the reasons, most code officials frown up on any ATS being used as a junction box.

You did not mention the size of purpose of the tap, but I would stay away from any sizable tapping in 3000A ATS as well, as dpc said.

Rafiq Bulsara

http://www.srengineersct.com