Stronger electric lights

Want to put some better lights in my tractor shed. Can I put 6 300 watt bulbs on one circuit with 12 3 wire? If I can, can I use a 15 amp switch? How do you figure how much amps are used in watts? Like how much amps would a 300 watt bulb use? It would be a short distance from fuse box to lights. Thanks for any help. Bryan

Divide voltage into watts. That gives you current (Amps) 14 ga wire will carry 15Amps, 12 ga wire will carry 20 amps

Should not be a problem. I would look for a more efficient light. 15 amp switch is at the limit but will probably work for a good long while. You say 12-3 are you talking 12-2 with a bare ground?

Power = Volts x amps

so

amps = power/volts

However that is only the math... in reality give yourself 10-20% for overage. Many items, when mass produced are 10-20% off their rated capacity.

Secondly, skip buying a less than $1.00-15 amp switch. Buy the better one, less arcing, will last way longer.

Like outlets, I never buy the 15 amp cheap ones anymore. They mess up the plug by having too little contact area.

Bryan, since Watts = Volts x Amps (were talkin unity 1 Power factor here with a pure resistive load), 6 x 300 = 1800 total watts divided by 120 volts = 15 amps in the branch lighitng circuit.

If using 12 gauge conductors Id still (old engineering habit and practice) use an 80% max for a continuous load and 80% of 20 amps is 16 amps so YESSSSSSSSSSSS 12 Gauge wire will work.......(still somewhat subect to temperature and insulation and number of conductors in an enclosure etc etc etc)

While a 15 amp rated switch is rated to handle 15 amps, I never liked to design right up to the limit and usually applied an 80% factor, so I would prefer a switch rated at 20 amps OR ELSE use a lighting contactor (relay) and they even make circuit breakers suitable for switching use as I recall (been retired tooooooo long lol)

Id be comfortable with a 20 amp overcurrent protection device (circuit breaker or fuze) on a branch circuit of 12 gauge wire.

NOTE Incandescent arent very efficient (Lumens per watt) sure you dont want to consider at least Fluorescent (can use high efficiency ballast rated for cold temp starts ya know) lamps or even High Intensity Discharge (HID) lighting such as coated Metal Halide which yield a decent color rendition. Sure the initial cost is much higher butttttttttttt you get much longer lamp life and much lower electric utility cost

Best wishes

John T

How far is your feeder wire frokm the source? In other words...how far to the shed?
They have some neet new light fixtures that pull far less power.
I put up 3 two f.light fixtures in the shop a week ago...total is 6A and it's almost too bright.

How far is your feeder wire from the source? In other words...how far to the shed?
They have some neet new light fixtures that pull far less power.
I put up 3 two f.light fixtures in the shop a week ago...total is 6A and it's almost too bright.

Am going to use the new "pig tail" shaped bulbs.. Will use a lot less electrity, and they give off plenty of light. Thanks for all your help in helping me decide what to do. Bryan Ia