light switches - rear insertion of wires

jimu57

New member
I am working for a lady doing various home fix up stuff. She has 2 bathroom lights that dont work. When you turn the switch on, there is a "sizzle" sound. I pulled the switch out of the wall box and saw that the wires were inserted in the rear. Checking the continuity, the switch seemed bad so I cut the wires and removed the switch. The switch was rated for 14 ga rear insertion but the electrician had 12 ga inserted. I have no idea how he got 12 ga wire in those smaller holes. Anyway, I drilled out the rivets on the switch so I could see inside. The plastic portion was black and burned. Could forcing a 12 ga wire into the back have caused this? And do you think the electrician possibly enlarged the holes so 12 ga would fit? I havent checked it out that far myself. There are several switches that I feel are not safe. another one "sizzles" when trying to use it. Some dont "feel" right when flipping the toggle.

My biggest concerned it that the electrician is enlarging the rear holes to allow 12 ga wire to be inserted. I am going to show this to the local building official who also inspects residential constructions. Something isnt right about this. Can anyone direct me where in NEC that talks about switches and NOT using improper rear connect wire size and also to NOT modify the switch? thanks
 

Dennis Alwon

Moderator
Staff member
Art. 110.3 is the best you will find-- The product is listed for back wire of #14 not #12 so it is a violation. The older switches use to accommodate #12 so it may have been compliant when installed.

BTW this is a site for electricians etc so we cannot give any how to advice.
 
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mwm1752

Senior Member
I once had to trouble shoot flickering lights At William Blatty's house early 1980's-- There was a bit of irony on that call -- The old stab lock devices are notorious for your issue -- Personnally I used the screw connection in device installs -- Makes service calls an easy fix & probably was a set up for the AFCI invasion
 

kwired

Electron manager
I am working for a lady doing various home fix up stuff. She has 2 bathroom lights that dont work. When you turn the switch on, there is a "sizzle" sound. I pulled the switch out of the wall box and saw that the wires were inserted in the rear. Checking the continuity, the switch seemed bad so I cut the wires and removed the switch. The switch was rated for 14 ga rear insertion but the electrician had 12 ga inserted. I have no idea how he got 12 ga wire in those smaller holes. Anyway, I drilled out the rivets on the switch so I could see inside. The plastic portion was black and burned. Could forcing a 12 ga wire into the back have caused this? And do you think the electrician possibly enlarged the holes so 12 ga would fit? I havent checked it out that far myself. There are several switches that I feel are not safe. another one "sizzles" when trying to use it. Some dont "feel" right when flipping the toggle.

My biggest concerned it that the electrician is enlarging the rear holes to allow 12 ga wire to be inserted. I am going to show this to the local building official who also inspects residential constructions. Something isnt right about this. Can anyone direct me where in NEC that talks about switches and NOT using improper rear connect wire size and also to NOT modify the switch? thanks
Use of the "push in" terminals is generally done to reduce time needed to install, would seem to me that the time it takes to enlarge the holes (if that is what was done) would take just as much if not more time than just looping the conductor around the screw terminals:roll:
 

PetrosA

Senior Member
Sure it could have caused this. The devices I've seen have a tab design where one plate is static, the other part of the tab is dynamic. Depending on the gauge of the wire the angle of the dynamic tab changes. If the wire is larger than the dynamic tab is designed for, there won't be clamping force against the wire. Once that happens, all you need to to push the device back into the box and the wire can spring to the side so it only makes contact at one point instead of along the length of the static tab. Load capacity is lowered now and you've got yourself a device rated for NOM Seventy-sizzle. ;)
 
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