Anwar Pasha
Member
Is it essential (as per code) to install a disconnect switch between transformer and ATS. The installed ATS has the ability to test the generator on load and no load without disconnecting power of the services main!!
Is it essential (as per code) to install a disconnect switch between transformer and ATS.
The installed ATS has the ability to test the generator on load and no load without disconnecting power of the services main!!
Would you please guide me where can I find in NEC stating that Disconnect Switch is not required between ATS and Transformer.
Thank you very much for your response. The reason being assigned for having a disconnect switch between TF and ATS by the consultant is to ensure ease in maintenance without any intervention from the Utilities . Would you please guide me where can I find in NEC stating that Disconnect Switch is not required between ATS and Transformer.
You will find no such wording, the NEC is a permissive document. You would have to find wording that requires a disconnect switch ahead of the ATS but there is no NEC section that directly requires that.
If this transfer switch is supplied directly from the utility it is required to be a 'service rated' ATS and that means it is required to have externally operated manual controls to lock both sources in the off position.
Of course these controls do not stop the power from entering the ATS cabinet and the NEC does not require that. It is a just a design decision.
I agree with you that servicing this arrangement is problematic but it is not an NEC violation.
You will find no such wording, the NEC is a permissive document. You would have to find wording that requires a disconnect switch ahead of the ATS but there is no NEC section that directly requires that.
If this transfer switch is supplied directly from the utility it is required to be a 'service rated' ATS and that means it is required to have externally operated manual controls to lock both sources in the off position.
I installed a couple of transfer switches last year that were service rated. They had the breakers inside and control switches on the outside, however in order operate manually you had to open the front door which exposed terminals. I thought it was a code violation and over all a crappy set up. I voiced my opinion, but no one listened and the AHJ was ok with the set up. I don't think he caught that section of the code that requires manual operation. I think the next one I do I will be more persistent. They are water pumping stations and we service them. I hate working one them cause I gotta suit up anytime i want to do something.