A step down transformer can do it safely. However there is going to be some loss of efficiency with actual loading so a step down of 1:0.5 ratio can do it the power required is to be implemented.
Assuming that your voltage is 120 volts the maximum wattage on that circuit is W = A x V = 15 x 120 = 1800 watts. Code only allows circuits to be loaded up to 80% capacity. 1800 x .8 = 1440. 1440/25 = 57 lamps. Assuming that your voltage is 240 volts the maximum wattage on that circuit is W = A x V = 15 x 240 = 3600 watts. If the question is from a 240 volt country you will have to find out what the local electrical regulations are for circuit loading.
The 208 volt configuration is one phase of a three phase source at 240 volts, where the 208 volt circuit is connected between the center tap of one 240 volt phase (usually a grounded neutral, in the style of a standard 120/240 split phase system) and the high delta connection on either of the other two phases. 208 circuit would consist of two phases of a 208 volt wye system or could be all three phases. The voltage between conductors would be 208 volts. The voltage to ground from any phase would be 120 volts. A 240 volt delta system would give you a high leg to ground, somewhere around 190 volts and the other two would be 120 volts to ground.
Hair dryers usually have a HIGH and a LOW setting. The HIGH heating element is about 8 ohms. The LOW heating element is about 32 ohms. voltage (squared) / resistance = power (watts) 120*120 / 8 = 1800 watts ( HIGH ) 120*120 / 32 = 450 watts ( LOW ) When the voltage switch is set to 240 volts, ALL it does is limit the HIGH/LOW switch to the LOW setting. 240*240 / 32 = 1800 watts ( LOW ) 240*240 / 8 = 7200 watts ( HIGH ) (the heating element would burn out)
To provide 240 ohms of resistance. What those 240 ohms do in an actual circuit depends on the intention of the designer.
240 watts at 120 volts requires 2 amperes. Power = voltage * current
There are 240/2 = 120 of them
Yes, you can always have heavier wire than code requires.
all voltage is plus or minus 10% of rating
yes
240+120=360.
Yes. In a 240 volt circuit, the total applied voltage is 240 volts but each leg is carrying only 120 volts.
The LCM is 240.
The white (or neutral) wire is not involved in a 220 circuit. Using US NEC conventions, red and black in a 120/240 split phase service form the 240 (220) circuit. The neutral (white) wire is only used when you want 120 (110) volts.
Both legs of a 240 branch circuit need to be fused with a fuse rated at 240 volts or better. The voltage potential across the load is what governs the fuse voltage ratings.
Assuming that your voltage is 120 volts the maximum wattage on that circuit is W = A x V = 15 x 120 = 1800 watts. Code only allows circuits to be loaded up to 80% capacity. 1800 x .8 = 1440. 1440/25 = 57 lamps. Assuming that your voltage is 240 volts the maximum wattage on that circuit is W = A x V = 15 x 240 = 3600 watts. If the question is from a 240 volt country you will have to find out what the local electrical regulations are for circuit loading.
This question makes no sense unless you mean volts instead of amps. And no, not for residential. Your panel feeds 120 volts or 240 volts depending on the way things are hooked up. You can wire circuit that is currently connected 120 as 240, however unless it is a dedicated circuit, YOU WILL BLOW UP YOUR APPLIANCES. Consult a qualified electrician.
divide 240 by 2 and.. voila.. you get 120!