Low Voltage Lamps
Do they save you money?
How It Really Works
For Electrical Power System Types in the Dallas Texas Area, TXU Energy is the provider of electrical distribution. They also maintain overhead and underground Primary Service. The secondary or stepped down voltages utilized by most businesses and residential customers are as follows:
Commercial Voltages: 480Y/277volt 3 phase 4 wire 240/120 Delta 3 phase 4 wire (High Leg is "C" on meter, "B" on load) (High Leg is 208v to ground) 208Y/120volt 3 Phase 4 Wire 240/120volt 1 Phase 3 wire
Residential: 240/120volt delta 3 phase 4 wire ( This is supplied to some older homes in the Dallas Metroplex) 240/120volt 1 phase 3 wire (This is the most common voltages for residential customers in Dallas) TXU Voltage Systems Advantages/Disadvantages 480Y/277volt 3 phase 4 wire system pros. Higher voltages will mean smaller conductor sizes may be utilized for similar loads. For example: Forty 400 watt High Bay fixtures with a ballast rating of 1.0 will require 16000 watts plus continuous duty rating of 125% or a total of 20000 watts. At 480 volts the demand is 42 amps (20000 / 480 = 41.67) Or (3) three 20 amp 480 volt circuits. Each requiring (generally) a #12 THHN Copper Conductor. If the applied voltage were 120 volts, then the 20000 watts would be divided by 120. (20000/120=166.67) or 167 amps! That would take (11) Eleven 20 amp 120v circuits and more than 3 times as much copper #12 conductors. The savings then for the higher voltage system is in the installation and the resulting saving in material and labor.
Myths About Electricity
In Dallas, many times I heard people say that with Higher Voltage Systems their electric bill will be less. This is FALSE. You pay by the kilowatt hour or per thousand watts per hour. An example is a simple appliance, a hair dryer. Lets say it operates at 1000 watts. And lets say you pay 14 cents per kilowatt hour. If you run your 1000 watt Hair Dryer for one hour it will consume 1kilowatt of energy and you will be billed for 14 cents. if your hair dryer or appliance operates at 120 volts and uses 1000 watts, then the formula is 1000/120=8.33 The hair dryer or appliance used 8.33 amperes at 120v and therefore uses 1000 watts of energy. If that same appliance was to operate at 240 volts, then the following would be true: 1000/240=4.16 amperes. Yes, fewer amps but the consumption of watts, (What we pay for) remains the same. One more example: Low Voltage Lighting does NOT save you money on your electric bill. Here's why. Lets say you have (20) twenty, 50-watt lamps operating at 120 volts. And using 1000watts at 120 volts. 1000/120 = 8.33 amps at 120 volts but still 1000 watts. Now lets use (20) twenty, 50-watt lamps operating at 12 volts. 20 x 50 = 1000/12=83.33 amps x 12 volts = 1000 watts. So by utilizing a transformer to reduce the voltage, you will INCREASE the required conductor size(s), and you will have NO EFFECT on the wattage. You will still pay for the 1000 watts or 1 kilowatt.