Electrical – get continuous power from a light controlled by a switch

Basically, you want to start with a switch. You run a black and white wire in from the bottom of the switch box (from the panel). This will take the form of 12/2 or 14/2 cable. You run another 12/2 or 14/2 cable from the top of the switch box to the first light. You connect the black wire to the switch. You connect the 2 white wires together, and then connect the other terminal on the switch to the black wire of the cable leaving this junction box towards the first light. The ground wire should also be connected together in this manner, but to the ground terminal on the switch. Each light will have a cable "entering" (from the switch) and "exiting" (away from the switch). At each light you'll connect the entering and exiting black wires together, as well as 1 terminal on the light. Do the same with the white wires. If there is a ground terminal on the light, do that as well, otherwise just connect the incoming and outgoing ground wires together. At the last light, just connect the incoming black wire to 1 terminal on the light, and then connect the white wire to the other one. This method is called wiring in parallel, so if one light blows, the current can still continue to the other lights to light them up.

Some other things to be aware of:

Most home wiring is either 12 or 14 gauge, corresponding to either a 20 amp or a 15 amp circuit, respectively. The maximum "design capacity" is 80% of that. Let's say you're using a 20 amp breaker with 12 gauge wire. This circuit should run at no more than 16 amps. Let's assume you're using 100 watt bulbs at 120 volts. Using watts/volts = amps, for 600 watts/120 volts = 5 amps. So this would work fine on a 15 amp breaker, depending on what else is on that circuit. http://www.thecircuitdetective.com/ is also a superb reference for novice electricians to get an idea of how things work.

Something like this is what you're looking for the end result to be:

The basic problem is that the occupancy switch that you chose to purchase is one designed to be able to work in series with the load attached to it. If the attached load is too small (too low of wattage) the switch assembly does not get enough power to operate correctly. For the particular model you have this is on the order of 40 to 50 watts of minimum load. From a technical standpoint it kind of sucks that they work this way BUT they are designed to work in place of a simple light switch that is in in series with its load.

Your Radio Shack relay does not come close to representing a 40-50W load on the switch so the only other way is to add some additional load in series with the switch (i.e. equivalently in parallel with the relay coil). As you have come to see this is not a very satisfactory solution and some other scheme needs to be found.

The best situation in this case is to acquire the alternate type of occupancy switch as mentioned in that thread that you linked. That type of switch has a live AC lead and neutral AC lead connected to it to power the switch unit irrespective of the size of the load. A separate output connection goes off to the load you are trying to switch. This type of switch may take a little re-wiring in your garage but that should be easier than trying to wire in the kludged extra load that the current switch requires. If you choose to deploy this improved version of the switch you will be able to remove the Radio Shack relay from the installation.

To make yourself feel better about the fact that you now have an extra occupancy switch you could pick a room in your house that has a tendency to get its light left on accidentally and install the extra unit in place of its light switch. Maybe this is a bathroom the kids use or a far closet that does not get used often.

BTW

It looks like Leviton now has a whole slew of different model occupancy switches that are also designed for single pole switch replacement but have removed the minimum load requirements. These do not require a neutral wire connection but do require a GND wire connection.