It sounds like you might be new to the model railroad hobby. I wonder if your term loop means just a "circular run around" or is it what we call a true "loop". Circular run arounds, a continuos track where the engine always goes the same direction on completion of the track's circuit is no hassle. However, a true "loop" is a single track that turns back on itself such that the engine is now going in the opposite direction on the same track. This is what a wye does, also. These will require a bit of planning, electrically.
Sorry if you are like me and are an old model rail just signed on to the forums. I just wanted to make sure I understood what you meant and that we were on the same page.
Are you running DCC or the old Analog DC train method? The solution to true loops and wyes are ideally, somewhat different for each type of operation. As the others mentioned, you had best read up on the electrical aspect or wiring if you have real loops and wyes on your planned layout.
DCC offers the easiest and lowest hassle electrical solution, albeit a triffle bit more expensive for loops and wyes. Analog DC operation will demand a bit of special wiring and that you must manually throw a switch while the engine is in the wye or loop to make a successful venture of the train effectively reversing its direction of travel.
Richard
If I can't fix it, I can fix it so it can't be fixed
Books are great references. If you are planning for DCC:
Basic DCC Wiring for Your Model Railroad
If you are planning for DC:
Wiring Basics From Model Railroader
The "Wiring for DCC" site recommended above is comprehensive, but can be somewhat intimidating if you have no prior background.
Layout Design GalleryLayout Design Special Interest Group
From your description, you're going to have electrical short circuits if you didn't plan ahead and put insulated rail joiners in the required locations if there are any inter-connections between your 'couple loops', especially when you add a wye or other turnouts.
You need to stop what you're doing and read a wiring guide other than something from Atlas. Their wiring guides are written specifically for Atlas Snap Track which is not the same electrically as other brands.
An Internet site called 'Wiring for DCC' would be a good place to start even if you're not going to be using DCC.
http://www.wiringfordcc.com/
Once you have laid a lot of track with electrical problems, even an experienced electrician would run from the room screaming when trying to solve the issues.
OK since I rushed my layout this far, Ive been trying not to think of the wiring i still need to do! Been putting off basically! The time is nigh! I'm expecting to drill a few holes no big deal. The only thing is I have no idea wut to wire and how much? My layout is an n scale 33"x79" with a couple loops and two bridges, One wye and one switch shortly after! Not sure if one set of wires tied to terminal track is good for the electric for the entire layout and another set of wires to the switch that would be too easy. I tried reading the Atlas wiring guide, but honestly it gets complicated quickly! Any help would be appreciated! Thanks!