Curious switch meltdown

[mrvm]

I’ve been in this home for over 30 years and this single pole 15 Ah switch has rarely been flipped on or off. The switch controls power to an external outlet. The external outlet powers a 60 watt transformer for low power LED lights for 5 hours each night. For some reason another lead off this light switch powers an outlet in the garage that has a Tesla slow charge 12A draw for about 5-10 hours a day.
One day last week I noticed the plastic switch plate to be warm-hot to the touch and opened the plate to discover the meltdown. I installed a new switch and everything is currently working fine. The plastic switch plate is cool and the exterior LEDs are working.
Moving forward the plans are to have an electrician upgrade to a Level 2 charger but wondering if a surge or the Tesla charger is causing this potential fire hazard / problem. The drywall screws was not my work

 

[Shiftless]

Charging a Tesla is asking that old light switch to handle lots of amps for lots of hours. Maybe a loose wire contributed to the heat. It will be much better after your electrician finishes a dedicated charging circuit for your car.

 

[wyliesdiesels]

A tesla charger should not be running thru that switch. how about doing a splice with a pigtail to the light switch?

 

[PCustoms]

I'm assuming "15 Ah" was a typo

What size wire feeds this switch?

What is the breaker size?

 

[mrvm]

I'm assuming "15 Ah" was a typo

What size wire feeds this switch?

What is the breaker size?

15 amp single pole toggle switch, the wires are 14-3 and the breaker 15 amp

 

[mrvm]

A tesla charger should not be running thru that switch. how about doing a splice with a pigtail to the light switch?

Apparently the builder had the switch controlling power to these outlets. I wouldn’t have known this to cause an issue 30 yr later. I agree a dedicated line or level 2 is in order for safe charging

 

[mm08822]

NM....post 6 addressed my q.

 

[PCustoms]

Was the hot wire wrapped around the switch terminal uncut/continuous? Or was it back-stabbed through it?

We not even looking at pictures now?



Certainly doesn't look backstabbed...

 

[mrvm]

Certainly doesn't look backstabbed...

The hot wire was continuous (bad) and the lead to power the garage outlet was back stabbed. After the meltdown that back stabbed lead to power the garage outlet was no longer back stabbed

 

[PCustoms]

The hot wire was continuous (bad) and the lead to power the garage outlet was back stabbed. After the meltdown that back stabbed lead to power the garage outlet was no longer back stabbed

The melted wire/terminal doesn't appear backstabbed

 

[mm08822]

We not even looking at pictures now?



Certainly doesn't look backstabbed...

Ok, your turn today to wear the hat.
Per the OP: "For some reason another lead off this light switch powers an outlet in the garage that has a Tesla slow charge 12A draw for about 5-10 hours a day." I only see a grd wire and and either a broken wire next to the bottom terminal or the "wires" next to the bottom terminal was one continuous wire. "off the light switch" is different than "through" the light switch. Last I knew switches need power in in and a load wire out.........
As I write this, the Op confirmed my suspicion.

 

[PCustoms]

Ok, your turn today to wear the hat.
Per the OP: "For some reason another lead off this light switch powers an outlet in the garage that has a Tesla slow charge 12A draw for about 5-10 hours a day." I only see a grd wire and and either a broken wire next to the bottom terminal or the "wires" next to the bottom terminal was one continuous wire. "off the light switch" is different than "through" the light switch. Last I knew switches need power in in and a load wire out.........
As I write this, the Op confirmed my suspicion.

I'll wear whatever you want me to wear....

But the melted part isn't backstabbed. If the feed to the charger was, and loose, is expect that to have melted down, not this side

 

[mrvm]

The melted wire/terminal doesn't appear backstabbed

That hot wire had a section of insulation removed and wrapped around the screw on the switch (continuous). I don’t think that would pass code but that’s where the meltdown occurred. The lead to power the garage outlet appeared to have been back stabbed as the copper wire was perfectly shiny, straight and not bent.

******I appreciate all the insight from everyone as this does not appear to be safe (not an electrician)****

 

[PCustoms]

That hot wire had a section of insulation removed and wrapped around the screw on the switch (continuous). I don’t think that would pass code but that’s where the meltdown occurred. The lead to power the garage outlet appeared to have been back stabbed as the copper wire was perfectly shiny, straight and not bent.

******I appreciate all the insight from everyone as this does not appear to be safe (not an electrician)****

Still have the switch?

Post a shot of the back straight on

Edit: also, how many additional wires were in the switch, 1 or 2?

 

[larry4406]

Looking at the pic on the desktop monitor, looks like an arc strike in RED and the black wire (circled in white) looks like it was looped around the screw..

 

[mrvm]

Yes. I’m at work now so I’ll post it later. IIRC one ground on opposite side top, one continuous on the burned area and one unconnected back stabbed wire floating in the box (I’m assuming back stabbed because it was not molested in any way. Probably why back stabbing is not a preferred method.

 

[mrvm]

Looking at the pic on the desktop monitor, looks like an arc strike in RED and the black wire (circled in white) looks like it was looped around the screw..

Correct. I was concerned about that arc strike. I was fortunate there wasn’t a fire.

 

[Bert_]

You put a good load on it for several hours. The connection was loose and got hot. Nothing too surprising.

That's why you have to make sure screws are tight and why you replace loose outlets.

 

[wyliesdiesels]

I'll wear whatever you want me to wear....

But the melted part isn't backstabbed. If the feed to the charger was, and loose, is expect that to have melted down, not this side

the back stabbed wire probably pulled out when he removed the switch from the box.... thats why you dont see it in the pic

Im guessing the backstabbed wire caused the overheating/melting NOT the wire loop around the screw.

 

[wyliesdiesels]

You put a good load on it for several hours. The connection was loose and got hot. Nothing too surprising.

That's why you have to make sure screws are tight and why you replace loose outlets.

doubt the screw was loose. as we can see something arced on the frame (probably the backstabbed wire) AND this isnt an outlet...

 

[PCustoms]

the back stabbed wire probably pulled out when he removed the switch from the box.... thats why you dont see it in the pic

Im guessing the backstabbed wire caused the overheating/melting NOT the wire loop around the screw.

I've personally never seen a loose connection create excessive heat somewhere else.

doubt the screw was loose. as we can see something arced on the frame (probably the backstabbed wire) AND this isnt an outlet...

I'm assuming the backstabbed wire was NOT the feed to the garage as the OP states, otherwise how would it arc. Thoughts?

 

[mrvm]

I've personally never seen a loose connection create excessive heat somewhere else.




I'm assuming the backstabbed wire was NOT the feed to the garage as the OP states, otherwise how would it arc. Thoughts?

I tested that feed to the garage outlet and it was not hot and was found detached when reviewing the situation. The cause of the arc is concerning since the “continuous “ wire did not come loose.

 

[wyliesdiesels]

I've personally never seen a loose connection create excessive heat somewhere else.

umm the "push-wire" connection aka backstab, is literally right next to and part of the same connection as the screw terminal.

and yes i have seen a backstab connection melt the side of a receptacle by the screw connection

 

[mrvm]

umm the "push-wire" connection aka backstab, is literally right next to and part of the same connection as the screw terminal.

and yes i have seen a backstab connection melt the side of a receptacle by the screw connection

Understood but the wire I suspect to have been a back stabbed wire did not test to be hot. That wire was clean, shiny, straight with no external damage. After I made all the same connections with a new switch there is now power to the garage outlet.

 

[PCustoms]

umm the "push-wire" connection aka backstab, is literally right next to and part of the same connection as the screw terminal.

Cool.

The backstabbed wire would have been on the same terminal that has the looped wire though

and yes i have seen a backstab connection melt the side of a receptacle by the screw connection

I would agree.

But not clear across the device

 

[TRWham]

I'll wear whatever you want me to wear....

The last time I made that offer it did not end well. Still have bad dreams...

 

[mm08822]

The last time I made that offer it did not end well. Still have bad dreams...

Scared the out of me too.....notice I didn't respond.

 

[PCustoms]

Scared the out of me too.....notice I didn't respond.

Don't get all shy now...

 

[gtae07]

Charging a Tesla is asking that old light switch to handle lots of amps for lots of hours. Maybe a loose wire contributed to the heat. It will be much better after your electrician finishes a dedicated charging circuit for your car.

We saw something similar at my parents' house a few years ago. Apparently all of the outlets in the garage were fed through one outlet in the guest bathroom. Poor thing suffered for years feeding a fridge, big freezer, Dad's tools, lights, and a golf cart charger, till one day it wasn't working and the back of the outlet was charred. I have no idea how they never tripped the breaker.

When the electrician came and redid the wiring with their addition, he fixed that and now the garage has its own dedicated feeds.

 

[Bert_]

doubt the screw was loose. as we can see something arced on the frame (probably the backstabbed wire) AND this isnt an outlet...

That is a classic loose connection. An arc to ground trips the breaker, it doesn't create the kind of heat that melted the switch.

 

[wyliesdiesels]

That is a classic loose connection. An arc to ground trips the breaker, it doesn't create the kind of heat that melted the switch.

unless its FPE or shitsco... ive literally been able to melt metal with a shitsco breaker

 

[mm08822]

The arc'd spot was someone's screw-up made with an inadvert touch of a hot wire to the grounded yoke. That trips a cb. Nothing to with the heating concern.

A loose connection or a high resistance forming from a deteriorating connection causes heat and meltdown. Not going to trip a cb. Even an arc fault cb could miss this if it deteriorated slowly enough with minimal arcing.

 

[mrvm]

The suggestion that the arc strike was a separate occurrence is plausible because other than the switch meltdown no other wires were burnt or broken to make the necessary contact. Based on some of the discussions I should focus on the 120V 5-10 hr 12A slow charging to be the cause for the switch meltdown or perhaps there was a storm related or heavy usage power surge or lightning strike. So far the replacement switch is cool to the touch as I work on getting some estimates for a dedicated line.

 

[Bert_]

Do you use the switch? Since you run this charger on it, sounds like no?

If you don't, just wire nut the wires together and do away with the switch.

 

[eejack]

I would think it is likely the switch itself just failed.

An outside event could have something to do with it but there would be evidence elsewhere ( electronics acting oddly or not functioning ).

The load on the feed might have overheated the screw terminal if the wire was damaged at that point ( 12A on a 15A wire that has been deformed could cause heating ).

A 30+ year old switch failing just seems more plausible.

 

[mrvm]

Do you use the switch? Since you run this charger on it, sounds like no?

If you don't, just wire nut the wires together and do away with the switch.

No. The switch is always on and controls an exterior outlet for the dusk-to-dawn 5 hr LED pathway lights. It was odd to find a straight undamaged single wire that supplies power to a garage outlet 25-30 ft away which I discovered was no longer attached most likely back stabbed.

 

[PCustoms]

No. The switch is always on and controls an exterior outlet for the dusk-to-dawn 5 hr LED pathway lights. It was odd to find a straight undamaged single wire that supplies power to a garage outlet 25-30 ft away which I discovered was no longer attached most likely back stabbed.

The wire must also feed your path lights, otherwise I can't see how they would be switched

 

[whateg01]

... I have no idea how they never tripped the breaker.

A high resistance connection does not trip a breaker. A short circuit or something drawing excessive current, like a short circuit, trip a breaker.

Are we sure that Mark is from an arc? It almost looks like the wire may have been up against that spot when it was hot and the insulation melted and left a little behind.

 

[mm08822]

A 30 yr old switch could have taken 1 or more shorts or grounds in its lifetime and kept on chugging along. The EVS load could have been the final stress on those switch contacts or stab springs.

 

[Bert_]

No. The switch is always on and controls an exterior outlet for the dusk-to-dawn 5 hr LED pathway lights. It was odd to find a straight undamaged single wire that supplies power to a garage outlet 25-30 ft away which I discovered was no longer attached most likely back stabbed.

Then connect the two wires with a wire nut. The switch is just a failure point.

These cheap residential switches won't hold up to that kind of continuous load.