Calculating electrical requirements, assistance requested.?
Question:I'm putting pot lights in my basement, and would like to ask the electricians out there how many 50 watt bulbs can I safely put on a single 120 volt circuit., assuming this is a dedicated circuit?
Answers:
Your circuit will be either 15 amps or 20 amps (it is normally printed on the breaker). You can attach up to 36 bulbs to the 15 amp breaker without tripping it or 48 bulbs to the 20 amp breaker BUT you are only suppose to attach 80% of that many for extra safety giving you the numbers 28 and 38 bulbs respectively.
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I see someone else says leave 30% but the NEC (National Electrical Code) says you only need to leave 20%. They also did their calculations with 60W and you said 50W
Whether they are incandescent or flourescent, 60W draws roughly 1/2 amp. (60W/120V = 0.5) .
A 15 amp breaker could handle at most 30 bulbs, although I would leave a reserve of at least 30%. This would mean about 22 bulbs. A 20 breaker would do more bulbs.
Depends on the ampacity of the circuit.
15a, 28 lights
20a, 38 lights
here is the math; power (Watts) is calculated Volts x amps=power (Watts) ie. 120v x 20amp (breaker used)=2400Watts overload current per breaker. 2400W x 80% safety margin = 1920Watts after correction. 1920W / 50W lamps = 38.4 lamps. Also try http://www.elec-toolbox.com/ for several usefull calculators.
15 amp circuit use 14 gauge wire you can have 28 such fixtures per National Electrical code.
20 amp circuit use 12 gauge wire you can have 38. I don't recommend 12 wire unless you have some experience as it is more difficult to work with, and also more expensive.
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