M asked in Science & MathematicsEngineering · 6 months ago

A household circuit rated at 120 Volts is protected by a fuse rated at 15 amps. What is the maximum number of 100 watt light bulbs?

A household circuit rated at 120 Volts is protected by a fuse rated at 15 amps. What is the maximum number of 100 watt light bulbs which can be lit simultaneously in parallel in this circuit without blowing the fuse?

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  • 6 months ago
    Favorite Answer

    one bulb draws a current of

    P = EI

    100 = 120I

    I = 100/120 = 5/6 amp

    15 amps / (5/6 amp/bulb) = 15•6/5 bulb = 18 bulbs

    (this is school problem answer)

    but fuses and bulbs have tolerances, so you need to reduct that to 16-17

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  • Sean K
    Lv 5
    6 months ago

    The electrical code says 12.

    • Sean K
      Lv 5
      6 months agoReport

      8-304(c) "Where the connected load is known, the number of outlets shall be permitted to exceed 12, provided that the load current does not exceed 80% of the rating of the overcurrent device protecting the circuit."

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  • M.
    Lv 7
    6 months ago

    My selfish, safe, personal opinion is:

    15 amp, 14 gauge wiring, times 80% equals 12 continuous amps, 24 hours per day.

    Pretending that there is a true 100 watt bulb and 120 volts, such a bulb will draw .8333 amps.

    So, 12 usable amps divided by .8333 amps equals 14.4 bulbs.

    So MY answer is 14 bulbs.

    24/7. No overload.

    1400 watts total.

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  • 6 months ago

    120*15/100 =18

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  • 6 months ago

    18 100 watt light bulbs

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  • 6 months ago

    18 pieces 100w light bulb.

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