In the USA the usual feed is 220.240 VAC. This is 2 phase, 3 wire and homes are generally on one side or the other giving 110 or 120 VAC to the sockets. This is all over the web and I will only summarize here.
Most panels have two rows of breakers, left, right or sides.
Powerline just needs to be on the same side. If not it might not work. But there are bridges an electric technician can install if need be (what it is, is on the web.)
Also, about the Access Point. You may want to consider models like
https://www.amazon.com/dp/B00OIA1Z9I?psc=1&smid=A2F6E975V906X0
The range extender in my home recently went out and as it really only covered one room with few devices connected to it, as long as it worked,I never had the need for it to have the latest and greatest extender. But now it seems I am in the market for a new way to extend to range of my wireless network. So as I was looking to get a new range extending device I was reading more about powerline adapters.
Everything I have read says that all units need to be connected to the same circuit that the main hub connected to your router is on. I have two circuit breakers in my home, a main one and a smaller one. By "same circuit" does that mean that they both have to be simply connected to the same circuit breaker box, or do they all need to be connected to the same switch in my circuit breaker? If so that will be a waste of time as there are around 30 switches in my main circuit breaker and where I would need to place it, while it would be on the same breaker would certainly not be attached to the same switch.
Ideally I would like to set up one as an access point and have it just create one big seamless wireless network rather than two separate ones that would result from a range extender but I don't want to waste my time if that isn't feasible.

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