Main Backup transfer switch.

[Milton Shaw]

I may install a 200 amp transfer switch for my mother-in-law for a backup generator. This would go between the meter and the original main breaker box. My question is. Does this make the main box now a sub panel and does it require separate grounds and neutral bars, and does that also mean that it has to be brought up to 2011 code with arc-fault etc. I have worked around electrical work for over 50 years but so many things were changed in 2011 code, I don't know the answer.

 

[ElvisBruski]

I understand this is a theoretical exercise, so I will give you a couple of pointers.
Choose a switch that will have a capacity to switch a solenoid and will drop out that contact when the engine starts. In effect t two contactors, one to start the and keep the engine running and the other to run the pump. Next you need the switch (contactor) to be have a no volt relay, in that the power is always supplied to the pump when closed, but when power goes off the relay drops out and closes the normally open relay supplying power from the engine and powers both the pump and the starter for the engine. The second sould have a timer or sensor for the relay so that when the engine starts the small relay drops out and stops the starter motor from turning when the engin eis running. It is not a hard concept to imagine.

 

[mrb]

the generator connected to the automatic transfer switch has to be sized to carry the entire connected load. You may consider leaving the main panel as is, putting an ATS between it and a new subpanel, and relocate circuits you want backed up to the subpanel

 

[theoldwizard1]

Does this make the main box now a sub panel and does it require separate grounds and neutral bars, and does that also mean that it has to be brought up to 2011 code with arc-fault etc.

Interesting that the 2 replies don't address the OPs question !