Can only using Ohm Meter, we can determine if the bulb is fuse or not

Discussion in 'General Electronics Chat' started by Raees Kakar, Nov 2, 2015.

  1. Raees Kakar

    Thread Starter New Member

    Nov 2, 2015
    1
    0
  2. alfacliff

    Well-Known Member

    Dec 13, 2013
    2,449
    428
    if infinate resistance, the bulb is bad., good bulbs read fairly low resistance.,
     
  3. ericgibbs

    AAC Fanatic!

    Jan 29, 2010
    2,503
    380
    hi,
    Usually the working voltage and wattage are marked on the bulb/lamp

    Using the formula Resistance = (Volt* Volt)/Watts will give the HOT resistance of the lamp when its operating normally.
    The COLD resistance is approx 10 times less.

    So a 12Volt , 1Watt lamp would have a HOT resistance of 144 Ohms and its COLD resistance approx 14 Ohms.

    E
     
  4. Roderick Young

    Member

    Feb 22, 2015
    408
    168
    If it's an incandescent bulb, it should read a few ohms. A fuse will basically read zero. Bulbs don't fail as shorts, in my experience (changed a lot of them in the days of pinball machines), so if you see zero ohms, it's sure to be a fuse. A bad bulb will read infinite ohms, same as a blown fuse, same as nothing connected at all.
     
Loading...