Here is a drawing I posted in another forum. Maybe it will help you a bit. I deleted most of the conversation but left a little of it remaining below:
A 240V outlet is simply connected to BOTH poles that have 120V each.
I have only shown double pole circuits for the large consumption appliances for the home, such as, Air Conditioning, dryer and stove top/oven. I have not included a refrigerator, separate freezer [if you have one like myself], multiple televisions, lights, stereos, gaming stations, computers, exhaust and intake fans for getting out the heat from rigs, etc. We have very easily maxed out this 200 amp breaker panel with what I have shown in the drawing without coming anywhere near the 32,000 watts of rigs mentioned in another post earlier. Plus, we don't have the other things necessary in the house like I mentioned.
A 200 amp main breaker is rated at what it says, "200 amps." Meaning, if we ever have more than 200 amps on either phase (pole), the main breaker will trip... period!!!
I'm not really worried about the main breaker. Just the small one headed into the bedroom where the router was installed. I think I may be running an extension cord from the hallway. Do you think 16 AWG cord would be sufficient for a single S7?
Yes, it's sufficient for your router but only one S7. It will get pretty warm but not hot with one router and one S7 on that 16 AWG extension cord. I'm assuming your are using a PSU(s) that can also plug into 120V?