Defective switch or a bigger problem?

Reply

  #1  
Old 06-24-17, 06:43 AM
P
Member
Thread Starter
Join Date: Jan 2015
Location: United States
Posts: 476
Received 2 Votes on 2 Posts
Defective switch or a bigger problem?

My office room has been wired recently for 20Amp - all outlets and 1 switch which controls only ceiling lights are all Spec Grade 20Amp rated.
All Romex 12/2.

Recently I noticed that while turning off lights..i think I saw a arch / flash inside the switch box.
Wasn't happening often and never was sure if it was just reflection or something imagined but being rather concerned AND because recently my Computer UPS would trip for a second while turning the lights on...I opened the box.
This is what I don't understand:
The wires were securely connected - no play...no contact between wires...
The switch was warped once with electrical tape which had burned hole where Neutral (White) was connected to the terminal.
I took the switch out and in fact there seemed to be some sort of reaction on that terminal (oxidation / burned tape??)
The wires look good coming into the box.

For now I replaced this switch with another brand new....but want to learn if this could have been caused by something else??

Also...anything I can test with a multimeter ?

Thank you

PS: This time I am NOT putting electrical tape around the switch screws.
 

Last edited by PaulSC; 06-24-17 at 07:08 AM.
Sponsored Links
  #2  
Old 06-24-17, 06:53 AM
pugsl's Avatar
Forum Topic Moderator
Join Date: Mar 2008
Location: United States
Posts: 8,657
Received 32 Votes on 29 Posts
Arcs are cause either by a loose connection or a bad contact. Why switch was wrapped in tape I have no idea. Sounds like a bad switch in your case. I just thought of one other cause is the switch is loose in box and moved to side, Wires contacted side of box. Maybe reason for tape.
 
  #3  
Old 06-25-17, 06:26 AM
Tolyn Ironhand's Avatar
Group Moderator
Join Date: Nov 2007
Location: Twin Cities, MN
Posts: 13,135
Received 93 Votes on 83 Posts
Many people will wrap devices with tape so there will not be accidental contact between the screws and a metal box. The burn mark could have been when the switch was installed and the tape didn't the job.

Any time you make a break an electrical connection with a load on the circuit you will get an arc. However, with a single room I would expect this to be a small arc and not able to be seen with a cover plate installed.

The switch was warped once with electrical tape which had burned hole where Neutral (White) was connected to the terminal.
I hope the white you have is a switch loop and you only have 2 wires (plus ground) in the box. Otherwise you are switching a neutral which is not good.
 
  #4  
Old 06-25-17, 06:33 PM
P
Member
Thread Starter
Join Date: Jan 2015
Location: United States
Posts: 476
Received 2 Votes on 2 Posts
Added the pics of the switch....

Name:  switch.jpg
Views: 101
Size:  19.7 KBName:  switch2.jpg
Views: 102
Size:  26.9 KB
 
  #5  
Old 06-25-17, 06:41 PM
P
Member
Thread Starter
Join Date: Jan 2015
Location: United States
Posts: 476
Received 2 Votes on 2 Posts
I will have to inspect the box up in the attic where I know there power comes in and splits to outlets and the light / switch..... I don't know if the neutral is being switched....since I don't see the black tape on the white wire end.
But wouldn't the outlets on this circuit show an issue....I remember testing them with that special device that shows various possible issues with different lights.
 
  #6  
Old 06-25-17, 07:03 PM
Tolyn Ironhand's Avatar
Group Moderator
Join Date: Nov 2007
Location: Twin Cities, MN
Posts: 13,135
Received 93 Votes on 83 Posts
I don't know if the neutral is being switched....since I don't see the black tape on the white wire end.
If you use a meter and measure between the white and ground and get 120 volts, it is a hot and not a neutral.
 
  #7  
Old 06-25-17, 07:06 PM
L
Member
Join Date: Nov 2015
Posts: 1,322
Received 41 Votes on 38 Posts
That looks like residue form the tape not burn mark. But the picture is too low of resolution to be 100% sure.

What you have there is a switch loop. Technically the white wire should been marked with a black tape, but I have never seen it done.

I only put tape around switches or outlets if they will not be installed in the junction box for a while (ie. during construction before putting drywall or tile).
Some people do it when they are being installed in metal junction box. There really is no point in taping when it is installed in a plastic junction box and on a remodel junction box.
 
  #8  
Old 06-25-17, 07:07 PM
ray2047's Avatar
Member
Join Date: Mar 2006
Location: USA
Posts: 33,597
Received 13 Votes on 11 Posts
That is definitely a switch loop in the picture. The box is plastic so no reason for the amateur's tape job.
 
  #9  
Old 06-27-17, 06:33 PM
P
Member
Thread Starter
Join Date: Jan 2015
Location: United States
Posts: 476
Received 2 Votes on 2 Posts
Guys - so I used a Volt meter.....I am getting 120V when connecting white to ground in OFF position with black showing 0V and when in ON position - I get 120V at neutral and hot....

I will need to go to the attic and open up the box where the power comes in and splits to outlets, lights and the switch.... clearly something isn't right
 
  #10  
Old 06-27-17, 07:08 PM
PJmax's Avatar
Group Moderator
Join Date: Oct 2012
Location: Northern NJ - USA
Posts: 55,228
Received 597 Votes on 562 Posts
I get 120V at neutral and hot....
That is NOT neutral. It was explained as a switch loop. Hot comes down on the white wire and gets switched back up on the black wire.

That is a perfectly normal type of setup.

Name:  switchloop.jpg
Views: 67
Size:  13.3 KB
 
  #11  
Old 06-28-17, 02:20 AM
C
Member
Join Date: Jun 2017
Posts: 41
Received 0 Votes on 0 Posts
What you have is a very common practice and if it works its safe and legal. If the switch is off and you test from white to ground you should get 120 and then test from black to ground and you should get nothing. Make sure the switch is off because if it's on while testing you will get a fulse read because it's under load so you can't tell what wire is actually feeding the sw so turn it of and test. It is just fine as long as it works. One last thing, a circuit under a heavy load can arc(spark or flash) chances are you didn't see that in this case but if you did it's only because of load like turning on your vacuum cleaner then plugging it in the wall, it will arc and it's normal. I hope this helps
 
  #12  
Old 06-28-17, 06:38 PM
P
Member
Thread Starter
Join Date: Jan 2015
Location: United States
Posts: 476
Received 2 Votes on 2 Posts
thanks - I misunderstood the reply by Tolyn ....I didn't know what it means to switch neutral and thought he meant that if Neutral is hot then it is in fact being switched.....which as said - it's not good.
 
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: