Controlling lane lights

I am building an arduino-based timer for the lights on my driveway. Its about 300ft long with 15 or so lights along it. Its wired with 10 gauge 3-conductor wire. The bulbs are CFLs, so probably 300 watts max which is split between the 2 circuits.

I'm a software guy, so that part is done (was a lot harder than i thought keeping UTC times and sunsets straight). Part I need help with is controlling the power. The easy answer would be the relay modules like this one:
http://www.miniinthebox.com/2-channel-5v-high-level-trigger-relay-module-for-arduino-works-with-official-arduino-boards_p1141409.html?currency=USD&litb_from=paid_adwords_shopping

The problem I see is that these little screw terminals on these things do not look beefy enough to grab onto a 10 gauge wire. Even if they were, are the traces on these boards thick enough to carry the amps which the relays are rated for?

It would be really nice if the relays could be mounted to a saddle-type thing so if they ever go bad i could just pop it out and stick the new one in there. Here's an example: http://www.frys.com/product/6406952#detailed

These will be mounted outside in an electric box. So no direct water exposure but there could be moisture and pretty wide temperature swings (in Iowa, so -20F in winter, 100 summer is about the range).

I'm not a hardware expert, so if it takes more than hooking the relay directly to the digital output of the arduino I'll need some hand-holding. Thanks!

The writing on the relays says they can handle 10 amps. Your 300w lights will be a lot less than that. If the 10G wire is too thick I would be tempted to use a short length of lighter wire to bridge between the heavy wire and the relays. You only need the heavy wire to minimize voltage drop over the long length of your driveway. A few inches of lighter gauge wire won't affect the total resistance significantly.

While the relays are clearly rated up to 250v the web page doesn't say if the complete circuit board is suitable for high voltage. It only mentions 5v - so you should check with the supplier. If it is rated for mains voltage it should have some form of official approval.

...R

I could extend the heavy gauge wire with some 14 gauge just to attach to this relay. I'm hoping though that someone can point me to a relay with screw terminals that will take the 10 gauge directly