Lighted Switch Problem

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  #1  
Old 08-27-12, 01:13 PM
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Lighted Switch Problem

The lighting circuit in my garage has a switch loop, to shut the lights off. The lights are pull-chain florescent lights. The switch is off; the light in the switch is bright. When the switch is still off, and I pull the pull chains on both the lights, (shut them off) the light goes dim, but power is not to them. Seems the switch might be bad, because there is a slight voltage on the top screw. Weird...Is this normal? The outlets test ok ....

First pic - Lights off, pullchains switched on.
Second Pic - Lights off, pullchains switched off.
Third Pic - Lights on, pullchains on.
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Last edited by rodog; 08-27-12 at 01:20 PM. Reason: word format
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  #2  
Old 08-27-12, 01:21 PM
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Your switch may need a neutral for proper operation. An older switch loop does not have a neutral.

With the pull chain off no voltage can trickle through the ballast.

You box should be grounded. How are you measuring voltage? Between what two points?
 
  #3  
Old 08-27-12, 01:36 PM
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Nah, the neon style basically just connect the bulb in parallel with the switch contacts. When the switch is off, a small amount of power 'leaks' through the fixture to create a complete circuit, and when the switch is on, the bulb contacts are shorted, which makes the bulb go out. I've never seen one of that style that requires a neutral.

It's actually similar in function to the automotive fuses that light up when they blow. When the fuse is intact, the bulb is shorted, but if the fuse blows, a limited amount of power backfeeds though the load and lights the bulb.
 
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Old 08-27-12, 11:14 PM
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cool, i guess ok then..............
 
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Old 08-28-12, 12:30 PM
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my friend is the one who checked it, and i think he said something like 40v was coming through. Top post on switch i think.
 
  #6  
Old 08-28-12, 01:30 PM
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my friend is the one who checked it, and i think he said something like 40v was coming through. Top post on switch i think.
There should be no actual potential on the switch yoke. 40V might be an induced reading.

Did your friend use a digital meter or an analog meter? What was the other probe touching?
 
  #7  
Old 08-28-12, 03:51 PM
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With the neon bulb in there you will have current flow with the swtich off because the bulb is in parallel with the switch.
 
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