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Does anyone know how many "can" lights you can put on one 20 amp circuit? I am wanting to put recessed lighting in my basement, and wanted to know how many watts, you can put on 1 ciruit?
 

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If memory holds correctly, you can determine load maximums per curcuit as follows:


Watts / Volts = Amps (Always derate to 80% maximum continuous load)


20 amps * 120 Volts = 2400 watts

2400 Watts * 80% = 1920 watts max continuous load


Add up the wattage of the bulbs you intend to use and see if it exceeds 1920 watts. If not, you should be good to go.


I'm not an electrician, so you may wish to consult a professional.


CJ
 

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P = VI

Power = voltage x current


1800 watts for 120 volt, 15amp circuit (1800 = 120 x 15)

2400 watts for 120 volt, 15amp circuit (2400 = 120 x 20)


That being said I am not sure if its code or rule of thumb to keep the load at 80% of the above numbers so 1440 and 1920 respectivly.


Also keep in mind any load that will be put on by recepticles on the same circuit if you dont have dedicated lighting circuits.


If you are using dimmers also check the rating of the dimmers. A lot of them are only rated to 600 watts and there are more expensive ones rated for 1000 watts. Those ratings are also reduced further on some modes in multi gang installations. For example I used some Lutron dimmers that were rated for 1000 watts, but the way they are designed the face of the dimmer (before you put on the cover plate) is a metal heat sync. When multiple dimmers are used together in a mutli gang installation there are tabs on the sides, part of the heat sync, that must be broken off (its made to break off) reducing the width unit and its cooling capacity. For example, a couple of my dimmers were mounted in the center two slots of a 4 gang box requiring tabs on both the left and right of the dimmer to be removed. This reduced the capacity of those dimmers by 200 watts each. This was burried in the fine print of the instructions of the dimmer that I would guess most folks would skip over and never see.
 
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