knob and tube wiring and led lamps

Status
Not open for further replies.
D

domnic

Senior Member
Occupation
Electrical Contractor
My neighbor lives in a 100 year old house. he replaced a incandescent lamp with a led lamp.in the bedroom in the upstairs of his house. their is some knob and tube in the upstairs . the new led did not work tried a another led same did not work. so I looked at it. I found the polarity reversed. so I changed the polarity at the fixture. works fine now. are all led lamps made this way ?
 
domnic said:
My neighbor lives in a 100 year old house. he replaced a incandescent lamp with a led lamp.in the bedroom in the upstairs of his house. their is some knob and tube in the upstairs . the new led did not work tried a another led same did not work. so I looked at it. I found the polarity reversed. so I changed the polarity at the fixture. works fine now. are all led lamps made this way ?
Click to expand...

While the actual light emitting diode is a specialized form of a diode the conducts current only in one direction, making it a polarized element of the circuit, it is required to work at a voltage much lower the normal 120 Volt AC that one finds on an existing Knob & Tube lighting outlet. An intermediate circuit, a driver, must be used to limit 120 Volt AC voltage and the current flowing in the actual light emitting diode.

It doesn't make sense that the "driver" would be sensitive to whichever Knob & Tube conductor is energized, especially because there usually is no Equipment Grounding Conductor present.
 
Last edited:
led polarity

led polarity

Since my last post in my shop I tried four different led lamps. with reverse polarity all worked fine. maybe I hade a pack of bad lamps ?
 
The process of correcting reversed wiring most likely corrected loose connections. Perhaps connections in the socket is loose.
 
Status
Not open for further replies.
Top