As the size of your layout increases, so too does the number of joints connecting the track sections.  The track joints introduce electrical resistance – the further (i.e. more track joints) you are from a power track or power tap, the more sluggish your cars will run.  This is especially true of cars with high performance motors.  Power taps are special track sections which will help ensure electrical power is distributed evenly around your entire layout.  A good rule of thumb is to include a power tap every 10 - 12 track sections.  Power taps will generally be made using straight sections of your track (though it is possible to use a curved piece of track if absolutely necessary).  Some other considerations when locating and installing power taps are listed below.

1. You may want to avoid placing power taps on elevated portions of your layout.  There is nothing inherently “wrong” with placing a power tap on an elevated section; however, it sometimes takes a bit more work (e.g. drilling, routing wire) when laying out and installing the power taps.  You may be able to juggle the location of power taps around your layout to minimize the number which fall in elevated sections.
2. If you are wiring a 4/6/8 lane layout, keep your power taps (and associated terminal blocks) adjacent to one another.  This will simplify your track wiring plan and make your life much easier once you start working under your table.
3. Your tables probably have structural components such as cross members which might be an issue when drilling holes for the power tap wires.  This is generally easy to work around – you can either move the power tap one track section in either direction or drill holes at an angle for the power tap wires to pass through the table without hitting the structural component.
4. Avoid having a power tap which doubles as your start/finish track section.  This is particularly true if you plan to include some sort of track sensor (e.g. SensorTrak) used in conjunction with a lap counter/timer or race management software.

The "Articles" section includes a write-up on making power taps for Scalextric Sport track.  You can purchase ready-made power taps for different brands of track below.

PLEASE NOTE:  Because power taps are custom fabricated based on your order, all sales are final.