Burnt Thermostat Wiring

[Rick Hurst]

Came across these burnt thermostat wires today. Has any one ever seen T-wiring burnt though as such. The wiring actually looked like it had been cut, but I can't figure out the burns on the wires.

Any ideas?

rick

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[Jerry Peck]

Rick,

Any other evidence of a lightning strike?

[Rick Hurst]

Couldn't find any sign of anything like that.

rick

[Charles Smith]

A typical thermostat circuit uses a 24 VAC low voltage transformer supply. The thermostat / heating controller may require 100 milli-amps to over 1 Amp.

So, if the wires were cut there would certainly be enough current to arc and melt / burn the insulating coating of the cable.

The short-circuit (instantaneous) (in mili-seconds) current can be in hundreds and even thousands of amps. Thus causing a lot of sparking and smoking.

Fuse protection of the T-stat voltage may or may not be implemented.

In my former career I tested medical device hardware and software... sometimes we intentionally short-circuited power supplies and sometimes it was a surprise test... arc smoke and fire. Nothing like a resistor or a power SCR burning up to clear out a lab.

[Jerry Peck]

A typical thermostat circuit uses a 24 VAC low voltage transformer supply. The thermostat / heating controller may require 100 milli-amps to over 1 Amp.

So, if the wires were cut there would certainly be enough current to arc and melt / burn the insulating coating of the cable.

I've never seen one with enough power to spark that much, but could be.

In my former career I tested medical device hardware and software... sometimes we intentionally short-circuited power supplies and sometimes it was a surprise test... arc smoke and fire. Nothing like a resistor or a power SCR burning up to clear out a lab.

The problem is not the cut wires or burned up components, the problem is that you 'let the smoke out'. Any one around electricity knows that you can never 'let the smoke out', otherwise it will no longer work.

[bruce m graham III]

looks like there might have been a plumber on site.

[Billy Stephens]

So, if the wires were cut

Charles,

Good theory but the wires are Rounded Over from being Burned.

[Michael Larson]

If that's thermostat, wire why do I only see one conductor?

[Jerry Peck]

If that's thermostat, wire why do I only see one conductor?

The way it arced through.

Look at the top section of the conductor and you will see the twists inside the outer sheath from the other conductors within the outer sheath.

My only problem with it being thermostat wiring and being cut did that is the arc flash was so hot that it bubbled up the outer sheath. The only way I can imagine that happening is if someone mis-wired something and put 120 volts (or even 240 volts) on that, in which case a cut could do that.

Maybe the transformer went bad, was mis-wired, who knows - I sure don't.

[Michael Larson]

The way it arced through.

Look at the top section of the conductor and you will see the twists inside the outer sheath from the other conductors within the outer sheath.

My only problem with it being thermostat wiring and being cut did that is the arc flash was so hot that it bubbled up the outer sheath. The only way I can imagine that happening is if someone mis-wired something and put 120 volts (or even 240 volts) on that, in which case a cut could do that.

Maybe the transformer went bad, was mis-wired, who knows - I sure don't.

I did notice the twist.

The copper looks awful shiny for having been exposed to an arc.

[James Duffin]

The cable in the picture looks like the type of cable used by the power company when hooking up their load management equipment. I would be interested as where the cable terminated on each end.

[Michael Sierra]

We had a similar situation happen to my inlaws, unfortunetly the issue caused a fie and the houes burnt down. It was a total loss but no one was hurt.

In there case a contractor had remodled the kitchen and wired a thermostat incorrectly. This caused the unit to alway be on, it was a local under the counter heater. The constant heat caused the wire to over heat and burn. The wire looked the same at the edges but with out the cut

[Jennifer Case]

Came across these burnt thermostat wires today. Has any one ever seen T-wiring burnt though as such. The wiring actually looked like it had been cut, but I can't figure out the burns on the wires.

Any ideas?

rick

hello I have something a little closer, and also found a board Level Burn that caused my Thermostat to burn the wires. See here these 2 pics will show what happened and this is why, the Removal of a Common wire in thermostats, yes this is why as a Test Tech I have found why this happens.

[Jerry Peck]

Curious as to why you came here, seemingly to ask a question, only to tell us how much more experience and knowledge you have?

Seems to me that the "question" was made up as you already knew the answer.

[Gunnar Alquist]

Off topic...

I noticed Rick Hurst started this thread 10 years ago. He hasn't been heard from in quite a while. Anyone have any news on him?

[Gary Burnett]

Off topic...

I noticed Rick Hurst started this thread 10 years ago. He hasn't been heard from in quite a while. Anyone have any news on him?

He still has an active license with TREC until 2018. Since our licenses are good for 2 years he renewed just last year. I did a home about a year ago that he had inspected for the seller. I think he just stopped using the forum.

[Garry Sorrells]

hello I have something a little closer, and also found a board Level Burn that caused my Thermostat to burn the wires. See here these 2 pics will show what happened and this is why, the Removal of a Common wire in thermostats, yes this is why as a Test Tech I have found why this happens.

Curious as to why you came here, seemingly to ask a question, only to tell us how much more experience and knowledge you have?

Seems to me that the "question" was made up as you already knew the answer.

Jerry, have to agree with the exception that I do not think Jennifer really has the knowledge to offer an opinion. She states that "as a Test Tech I have found why this happens." though she opened a thread questioning why her AC was not working and showing a picture from a old thread. Also obscuring the the burned board and notations. OR have I missed something.

There is a fried board. Exactly what fried and why may be the underlying question. The board burnt not the wires.

Then there is the question of "craftsmanship or design" and not knowing the difference.

[Jim Robinson]

I really wish we would close threads after 30 days, or some set period of time with no activity.

[Gunnar Alquist]

He still has an active license with TREC until 2018. Since our licenses are good for 2 years he renewed just last year. I did a home about a year ago that he had inspected for the seller. I think he just stopped using the forum.

Hi Gary,

Good to know, thanks. If you run into him (unlikely, I realize), let him know he is missed and HG is gone).

[cliff kornegay]

Hi Gary,

Good to know, thanks. If you run into him (unlikely, I realize), let him know he is missed and HG is gone).

What happen to HG Watson? Did anyone ever unmask his identity? The thread on his identity never reached a conclusion.

[Garry Sorrells]

Think Watson copped an attitude for being reprimanded and drifted off. . Or his Heath went South and his keyboard was taken away to keep his BP down.

[Gunnar Alquist]

What happen to HG Watson? Did anyone ever unmask his identity? The thread on his identity never reached a conclusion.

Think Watson copped an attitude for being reprimanded and drifted off. . Or his Heath went South and his keyboard was taken away to keep his BP down.

According to his IN profile, he last looked in on June of this year but his last post was in 2014.