JChenault
Well-Known Member
I had an interesting failure today. I'm trying to understand the physics of how it occurred.
I was doing some work and needed more light. I hooked up a 400Watt scoop and stuck it near my work space. Note that the scoop was not attached to a metal pipe, it was effectively sitting in a free air space.
After 30 seconds or so of use, I heard a loud arcing noise, saw sparks, and got some flames coming out of the pin plug. After what seemed like 10 seconds ( but was probably more like two) the breaker tripped and all was quiet.
I examined the plug and here is what I found.
![PinPlugArc1.JPG PinPlugArc1.JPG](data:image/svg+xml;charset=utf-8,%3Csvg xmlns%3D'http%3A%2F%2Fwww.w3.org%2F2000%2Fsvg' width='640' height='478' viewBox%3D'0 0 640 478'%2F%3E)
![PinPlugArc2.JPG PinPlugArc2.JPG](data:image/svg+xml;charset=utf-8,%3Csvg xmlns%3D'http%3A%2F%2Fwww.w3.org%2F2000%2Fsvg' width='640' height='478' viewBox%3D'0 0 640 478'%2F%3E)
Note that the arcing burned the ground and hot pin more than half way through.
When I put a meter on the fixture and discovered a short between the hot leg and ground ( not sure where that short is as yet as I need to take the fixture apart. I suspect that it is somewhere in the whip). I also discovered that the neutral in the male plug was not tightly connected.
Now I have no issue with the fixture developing a dead short between ground and hot. It does not happen frequently, but it does happen. My surprise and concern is that I got arcing between the hot leg and the ground on the pin plug. I am also surprised that the breaker did not trip sooner.
Anyone had a pin plug do this before? Any theories why I got such a spark between the pins?
I was doing some work and needed more light. I hooked up a 400Watt scoop and stuck it near my work space. Note that the scoop was not attached to a metal pipe, it was effectively sitting in a free air space.
After 30 seconds or so of use, I heard a loud arcing noise, saw sparks, and got some flames coming out of the pin plug. After what seemed like 10 seconds ( but was probably more like two) the breaker tripped and all was quiet.
I examined the plug and here is what I found.
![PinPlugArc1.JPG PinPlugArc1.JPG](https://www.controlbooth.com/data/attachments/4/4510-ce7842e4787cff2c43185f41fc733969.jpg)
![PinPlugArc2.JPG PinPlugArc2.JPG](https://www.controlbooth.com/data/attachments/4/4511-b313fe2605690c7ee1ef5c7334aeedd5.jpg)
Note that the arcing burned the ground and hot pin more than half way through.
When I put a meter on the fixture and discovered a short between the hot leg and ground ( not sure where that short is as yet as I need to take the fixture apart. I suspect that it is somewhere in the whip). I also discovered that the neutral in the male plug was not tightly connected.
Now I have no issue with the fixture developing a dead short between ground and hot. It does not happen frequently, but it does happen. My surprise and concern is that I got arcing between the hot leg and the ground on the pin plug. I am also surprised that the breaker did not trip sooner.
Anyone had a pin plug do this before? Any theories why I got such a spark between the pins?