2007-05-20 09:34:03 · 7 answers · asked by Tony K 1 in Science & Mathematics ➔ Engineering
Wattage divided by voltage will give you an ampere rating of the switch.
2007-05-20 09:39:38 · answer #1 · answered by Anonymous · 0⤊ 0⤋
Something to consider is that the starting current may be considerably higher than simply dividing the rated wattage by the voltage. For typical household size lamps, the manufacturer of the switch has probably allowed sufficient safety factor. But if designing a high wattage circuit, it is something to think about.
2007-05-20 16:56:02 · answer #2 · answered by tinkertailorcandlestickmaker 7 · 0⤊ 0⤋
The peak rating should be much higher than the amperage rating of the lamp, as the inrush starting current of an incandescent lamp is much greater than the operating current. The switch should conservatively be rated at least 200% of the steady state lamp rating at the maximum rated voltage for continuous rating. For intermittant rating, I'd want at least 500% of the maximum continuous lamp rating. So for example, for a 100Watt bulb. Figure 130Volts max voltage rating. 100 = VI = 130 * 8 approx. or 8 amps continuous. so 40A peak loading and 16A continuous rating. UL might require even more of a safety factor...
2007-05-21 00:37:56 · answer #3 · answered by squeezie_1999 7 · 0⤊ 0⤋
Determine the current through the circuit via Ohms law ie. current in watts divided by voltage. Thus for a 100 watt bulb you would calculate .83 amps or 830 milliamps. De-rate the switch by 10% ie .83 x .1 = .083. Add that to the current draw
.83 + .083 = . 913 amps. Using the de-rated current value you would then choose a switch rated for 1 amp. A good circuit designer will always de-rate a power carrying component by at least 10% to avoid premature failure of the device.
2007-05-20 21:35:05 · answer #4 · answered by John B 2 · 0⤊ 0⤋
I'd make sure that the switch was rated at least as high as the circuit breaker or fuse that feeds it. You really want your failures to occur in the circuit protection element.
2007-05-20 17:01:51 · answer #5 · answered by virtualguy92107 7 · 0⤊ 0⤋
The load circuit.
Higher the bulb wattage, the higher the load rating should be. When the load rating is excessive, it too becomes a factor.
(example)
You should not get a 200amp load rated switch for a 40w bulb.
2007-05-20 16:43:24 · answer #6 · answered by kegtapper01 2 · 0⤊ 0⤋
Calculate the max amps going through the lamp. ~
60W lamp at 120V 0.5amps.
2007-05-20 16:36:19 · answer #7 · answered by Anonymous · 0⤊ 0⤋