Why did my connection fail?

Reply

  #1  
Old 11-20-16, 01:50 PM
Member
Thread Starter
Join Date: Jan 2011
Location: US
Posts: 277
Received 0 Votes on 0 Posts
Why did my connection fail?

I had a recessed lighting fixture in my kitchen fail. I didn't know what to do about it, so I ignored it. A week later it started to work again, only to fail permanently 6 months later. (NoraLighting - 6" IC Air-Tight Line Voltage Housing)
I worked up the nerve to open it up and found the hot wire going from the quick connector in the junction box to the light was completely out of the connector. A second wire was half out of the same connector. It was tinned stranded wire.
But the crazy thing was that the loose wire was burnt around the insulation and the wire was about 75% burnt through right at the insulation. I cut it off, stripped a new end, and put it in a new connector.
I am making a wild guess that it was pushed in too far, so it wasn't making good connection with the conductor, was arcing and burning the wire and insulation.
But:
1) How did it survive 10 years of daily use like that, seeming to work fine. I would expect it to either be good or fail quickly.
2) How did it get out of the connector? If it was in too far, how did it come out completely? It was a good half inch from where it was burnt to the end of wire; why would it fall out?

Or do you have a better explanation for what caused my problem?

A bigger issue, is that I have 20 of these fixtures, some of them in 16' ceilings; all 10 years old. Am I likely to have problems with more of them?
Any help here would be much appreciated.

I actually got lucky that the bad connection was in the fixture that was out. I was planning on replacing the socket, thinking the heat sensor had gone bad, when I found the bad connection. The bad connection could just have easily have been in the junction box that fed it, and then I would have been totally perplexed when my replacement didn't help.
 
Sponsored Links
  #2  
Old 11-20-16, 02:02 PM
chandler's Avatar
Banned. Rule And/Or Policy Violation
Join Date: Dec 2005
Location: USA
Posts: 39,967
Received 3 Votes on 3 Posts
The tinned stranded wire was placed in the connector at the factory. By it being loose, it tells me it was a defect. I doubt it happened over time, but one day it woke up and decided to fail all of a sudden. The arcing would be normal with the connections coming loose until they finally separated enough to disconnect. The connections in all the cans are in junction boxes so a fire hazard is reduced considerably. If you want further satisfaction, you could put these lights on arc fault breakers. The only problem is you may encounter false trips on occasions.
 
  #3  
Old 11-20-16, 02:42 PM
pugsl's Avatar
Forum Topic Moderator
Join Date: Mar 2008
Location: United States
Posts: 8,559
Received 27 Votes on 26 Posts
The burnt wire was caused by the loose connection. It most likely over time with heat cycles when light was on, finally came disconnected. Are your lights mounted to electrical boxes? If so you should be ok but I would pull a couple of other ones down to check connections.
 
  #4  
Old 11-20-16, 02:42 PM
Tolyn Ironhand's Avatar
Group Moderator
Join Date: Nov 2007
Location: Twin Cities, MN
Posts: 13,025
Received 69 Votes on 61 Posts
The wire was likely not pushed in far enough. That caused the loose connection which caused heat, enough to melt the insulation.

While I see evidence of loose connections on service calls I do, I would not worry about it. Compared to the billions of splices made in homes and commercial buildings, they are a very small percentage.
 
  #5  
Old 11-20-16, 03:23 PM
PJmax's Avatar
Group Moderator
Join Date: Oct 2012
Location: Northern NJ - USA
Posts: 54,227
Received 479 Votes on 449 Posts
In some cases... those clips are not tight from the start.
With constant use and heat they fatigue further until they fail.
 
  #6  
Old 11-25-16, 09:23 AM
Member
Thread Starter
Join Date: Jan 2011
Location: US
Posts: 277
Received 0 Votes on 0 Posts
1) I checked a couple other fixtures. They look fine. Completely inserted; no burning.

2) I tried the old connector that apparently failed. It holds #18 wire pretty firmly. I had to twist and pull fairly hard to get it out.

3) I called the manufacturer. They say they just supply the connector; the installer puts it on the fixture wiring. They have never heard of a connector failing and assume the installer just didn't push it in very far.

But I am still confused. To be burnt at the base of the insulation, it had to be pushed in all the way; didn't it. I can see that it wasn't connecting properly, arced and burnt, then just fell out; but why does it connect firmly now?
 
  #7  
Old 11-25-16, 09:40 AM
pugsl's Avatar
Forum Topic Moderator
Join Date: Mar 2008
Location: United States
Posts: 8,559
Received 27 Votes on 26 Posts
Loose connection wire gets hot and insulation burns at end of wire, We see this all the time in service work.
 
  #8  
Old 11-25-16, 10:03 AM
Member
Thread Starter
Join Date: Jan 2011
Location: US
Posts: 277
Received 0 Votes on 0 Posts
Okay, I thought the burn would have to be right at the bad connection.

So... the wire was not pushed in enough to make a good connection in the first place. The bad connection causes heat that burns the insulation. After 10 year of being bad, it finally falls out.

That is not encouraging for the rest of the electrical work.
 
  #9  
Old 11-25-16, 12:24 PM
Tolyn Ironhand's Avatar
Group Moderator
Join Date: Nov 2007
Location: Twin Cities, MN
Posts: 13,025
Received 69 Votes on 61 Posts
That is not encouraging for the rest of the electrical work.
No, but it does happen as mentioned by me and Pugsl
 
Reply

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Thread Tools
Search this Thread
 
Ask a Question
Question Title:
Description:
Your question will be posted in: