I'm outfitting my long-dreamed-of comic shop with lighting (planning to open in January), and have purchased lighting fixtures to use 14-watt compact florescent reflecting bulbs (R20, with the standard base).Other options I looked at were to use the MR16 halogen bulbs, which give a good light quality but heat up and use much more energy.So, to add these lights, I'm going to have to add an additional 15-amp breaker to my box. The question I have is whether using a 12-volt lighting system (available with the MR16-type lights) saves any energy (kwh as charged by the electric company), or whether it just means I need more amps.Watts = Volts * AmpsFor example, a 30-Watt bulb is 30 watts at 120 volts, so it uses .25 Amps on a circuit.30w = 120v(.25Amps)On a 12-Volt circuit=30w = 12v(2.5Amps)Is that right?

You are essentially correct. I would go with the 120 volt anyway... that way you dont have to worry about transformers.

There's a lot to think about here besides just the volts and amps.Yes, your math is correct. The low voltage limitation is conductor size - it requires bigger wires for the 12V side. However, you'll be running 120V to the transformer that is close to the fixture(s), so that's not the issue it appears to be.A low voltage system will consume some more power per watt because the transformer is 'lossy'. However, there are some amazing and very fancy fixture systems available in low voltage. So, the 'look' you want figures in here.Flourescent alone may not be a wise choice for a comic book store. Despite manufacturer's best efforts, fluorescent light still doesn't render full-spectrum color very well. Especially those heavily saturate reds. Jewelry stores have been using quartz lights for years because of the light quality. Downside: expensive lights, and they get hot (ups your air conditioning load).Another option is incandescent PAR lamps. Decent light quality, less expensive, but again there's the heat.In general, when lighting colorful merchandise, you want lights with as high a Kelvin rating as you can afford to buy/install/operate/maintain. 6500K is a common choice (http://en.wikipedia.org/wiki/Color_temperature)Low voltage will have limits on how many lamps per transformer. You may have some additional installation expense associated with extra circuits from the panelboard; depends on local codes.You can keep lighting costs down by:Sticking to stuff that's commonly available in your area.Use fluorescent for general area lighting, and lights inside enclosed display casesAdd high quality lights for accent and feature lighting

you will use the same amount of energy. But you will need much larger wiring.Not to mention a transformer. Go 120 v.

When using 12 volts instead of 120 volts, the current load in your circuit will be 10 times higher than when 120 volts supply is used. Therefore, the circuit conductor needed will be larger in size. The disadvantage is your installation would be more expensive. On the other hand, a 12-volt circuit won't cause electrocution even if some terminals are not insulated.