Hi,
Yes, the WH7 can drive 4 lamps. The first and simplest way to connect 4 VHO lamps to one WH7 is to connect 1 bulb per set of wires. The WH7 has 4 sets of wires - each set is composed of one red wire and one yellow wire. Yupe..it will light, but it will not be very bright.
http://www.fulham.com/NewFiles/wire07.gif
The other method is to connect the lamps in series-parallel combination. Basically, we will connect two lamps together in series so that it looks like one long 8 foot VHO bulb. Then, connect the two 8 foot long VHO bulbs to the WH7 -- each 8 footer is connected to two red wires and two yellow wires.
http://www.fulham.com/NewFiles/wire11.gif
The third option is to use the WH8. Basically, a WH8 is two WH7 in the same package.
- Victor.