Nearly had a fire...need to understand why breaker didn't trip.

[rich_kildow]

I was gone teaching snowmobile safety with my daughter and checked my phone to find a series of frantic texts from my wife. Long story short, my garage heater (Dura Heat EWH9615 10k garage heater) shorted it's heating element. The heater is less than 10 years old and I blow it out every fall so it isn't heating up excessive dust from the off season. This was hard wired as specified, on a 50 amp breaker in an Eaton CH subpanel. The panel, breaker, and wiring existed when I bought the house 14 years ago, I simply upgraded the heater that was already there and an electrician connected it and popped in a new breaker.

After reviewing the camera, she closed teh back garage door to do something outside and the moment it closed, it lit up and sounded like a welder, dropping a few sparks in the process. According to her, it then started burn back in the element. After attempting a fire extinguisher briefly, she called 911 and then my parents, who live around the corner. Dad got there ahead of the first volunteer and flipped the breaker. In the less than 5 minutes that took, it had melted from about the 6 o'clock position on the first coil up to about the 12 o'clock position. The fire department did some poking around and determined the fault to be completely in the heater itself, not in the panel or wiring. A remark was made that these kinds of shorts often don't trip breakers.

So, now I'm freaked out and have some questions. I understand that **** happens and who knows what happened in that heater. Something obviously jostled just wrong and caused a short.

But why didn't the breaker trip? Off my basic understanding of electricity, I'm guessing that because a 50 amp breaker takes a lot to trip and a heating element has inherently high resistance, even shorting out and burning itself up the circuit wasn't pulling enough current long enough to cause a thermal magnetic breaker to trip...right?

I've left this heater on plenty of times when we were asleep or during a quick run to town to keep the garage up to temp to work, thaw deer, etc.

Is there a safer way to move forward? I keep trying to tell myself that this was a completely freak accident, but you only get away with so many of those before something else happens. I'm in NW WI and we're at -20 tonight, so I don't know that a mini split heat pump would be a great way to do things reliably, and they are expensive. A modine heater run off our bulk tank seems the next logical option, but that couldn't be installed until spring when we could dig up the propane line. I don't think I'm going to trust another electrical resistance heater for a while, and this wasn't some no-name Temu heater.

 

[whateg01]

The reason it didn't trip the breaker is that it didn't draw enough current. This is over simplified, but If you think about how the heater works, one end is connected to a voltage source, and the other is connected (shorted) to ground. So as long as the fault occurs far enough down the element, it isn't drawing any more current than it does in normal operation. I bet it would have eventually tripped the breaker.

 

[Shiftless]

Wow!
I‘m glad that people were around and it was caught in time. Total disaster averted this time. I understand your reluctance to install another one. Yet thousands of them are working hard this winter with nobody burning up.

A heater should be equipped with a thermal overload cut off switch. Overtemperature? Kill the power. Don’t rely on a circuit breaker in the panel. As explained earlier, that’s not in the design.

 

[CoogarXR]

But why didn't the breaker trip? Off my basic understanding of electricity, I'm guessing that because a 50 amp breaker takes a lot to trip and a heating element has inherently high resistance, even shorting out and burning itself up the circuit wasn't pulling enough current long enough to cause a thermal magnetic breaker to trip...right?

Right.

Sounds like an Arc Fault breaker might have tripped though. I'm sure somebody more versed in modern electrical panels will be along shortly.

 

[whateg01]

Right.

Sounds like an Arc Fault breaker might have tripped though. I'm sure somebody more versed in modern electrical panels will be along shortly.

Or gfci

 

[PCustoms]

Pretty accurate descriptions above

Pics of the heater would help with further diagnosis

 

[Shiftless]

That heater is supposed to shut itself off if it detects an overtemperature.

 

[mm08822]

The unit only draws 41 amps. It is code to be on a 50 amp circuit.

Unless the fault occurred between line terminals or line to ground where the current drawn exceeds 50 amps, the cb would not trip until enough heat damage destroyed electrical insulation to make either type of fault occur.

Possibly a gfci cb could have detected a ground fault IF that was the fault type.

I have never seen a 240v 50A afci cb.

Pics of the faulted area within the unit could be more telling.

Overtemp sensors are great if they happen to be located in the fault area. Most likely they are used to detect loss of fan/air flow. An element burning out won't necessarily cause that type of overtemp.

 

[rich_kildow]

 

[rich_kildow]

Thank you for all the replies. It appears that the short started at the very bottom of the free end of the front heating element. All the other heating elements look fine. I can see the discoloration and chime where the Sparks were thrown, and according to my wife and dad's descriptions, it had burned its way from the 6:00 position back up to 12:00 in those couple of minutes.

The explanations so far seem to make sense as to why the breaker hadn't popped and it hadn't triggered its own thermal overload protection. My wife said she tried to turn the unit off but couldn't but she was also pretty worked up in the moment. I don't know that she even knew the remote exists.

I think you guys are right. This was a freak accident that probably would have solved itself in just a few more minutes. I think if the coil had burned back to the 3:00 position, that would have positioned it above the overheat sensor and it probably would have cut out as it came around back to 6:00. At some point it would have also most likely flipped the breaker.

I'd love to know if a GFCI would have stopped this sooner. I know they make 50 amp GFCI dual poles for this panel, and I'm not above the $200 investment. If it gives me some peace of mind going with another electric heater like this.

 

[rich_kildow]

To be clear, the white powder is remnants of the fire extinguisher my wife hit it with, and those slats are missing because I just broke them off to get better pictures. The heater is well maintained and clean. I make a point to blow it out every fall before the heating season.

 

[dscheidt]

You might ask the manufacturer if they want to take a look at it.

 

[Junkman]

Check the Consumer Product Safety website to see if any other faults have been reported. Often, if they find that a product is having issues beyond normal, they will notify the manufacturer of the defect and issue a recall bulletin to the owners of record.

 

[rancherbill]

It's simple, it had an age related failure and a manufacturing defect from Day 1 of the Over Temp Shut Off device. Us manufacturers are not known for the highest quality standards or testing.

 

[whateg01]

It's simple, it had an age related failure and a manufacturing defect from Day 1 of the Over Temp Shut Off device. Us manufacturers are not known for the highest quality standards or testing.

The area where the over temp interlock is located might not have gotten that hot by then.

 

[mm08822]

User reviews on several sellers' sites have had the same problem. 10 years seems lucky.

Overall line of products from parent company have poor reputation.

Call customer service. They're in PA.

 

[MAD]

I suspect it would have just kept arching until enough of the element burned away to create large enough air gap to stop the arching.

I had an oven element self destruct a few years ago on Thanksgiving and it was like someone lit off a string of firecrackers in there. I was able to turn it off and finish the almost cooked turkey in my gas grill.

 

[Chuckster in NJ]

Don't do anything yet! CALL the manufacturer and tell them what happened……. They need to know this to prevent future fires or death.
Maybe these heaters need to have a National recall due to a failing heating element and unless these issues are reported the manufacturer thinks everything is fine.

TIP! Try to get an email address and document this problem.…… This issue could get very interesting.

 

[mm08822]

 

[whateg01]

The area where the over temp interlock is located might not have gotten that hot by then.

Looking at that pic, I doubt any over temp device would ever have tripped. While the temperature right at the area where it was shorting, probably the internal element to the external heat sink, would be pretty hot, it's very localized and short lived.

 

[kngelv]

Is there a safer way to move forward? I keep trying to tell myself that this was a completely freak accident, but you only get away with so many of those before something else happens. I'm in NW WI and we're at -20 tonight, so I don't know that a mini split heat pump would be a great way to do things reliably, and they are expensive. A modine heater run off our bulk tank seems the next logical option, but that couldn't be installed until spring when we could dig up the propane line. I don't think I'm going to trust another electrical resistance heater for a while, and this wasn't some no-name Temu heater.

It all depends what you want to spend and what you are comfortable with. A decent quality gas, propane or electric heater will work. Your heater might not be a Teemu but it's a pretty low quality Chinese model. I have a King Electric in one garage that's USA made but they do cost more. Modine makes high quality heaters so that's a good option. I just put a Fujitsu mini-split in my second garage and would never use anything else but they do cost more upfront. I wanted my garage heated 24/7 all winter so it makes sense for me. It's 4 degrees out but my garage is a balmy 64 degrees. Still waiting for that first bill though.

James

 

[rich_kildow]

It all depends what you want to spend and what you are comfortable with. A decent quality gas, propane or electric heater will work. Your heater might not be a Teemu but it's a pretty low quality Chinese model. I have a King Electric in one garage that's USA made but they do cost more. Modine makes high quality heaters so that's a good option. I just put a Fujitsu mini-split in my second garage and would never use anything else but they do cost more upfront. I wanted my garage heated 24/7 all winter so it makes sense for me. It's 4 degrees out but my garage is a balmy 64 degrees. Still waiting for that first bill though.

James

I've been doing some shopping around and you're right, I think these boxed coil heaters are pretty much all the same. Is there anything besides King that's of good quality and has an electric in the 7.5 to 10Kw range? I'd love to put a King unit in, but that's some next level pricing.

Comfort Zone, Dyna Glo, etc,.all seem to be the same thing, just priced all over between $200 and $500.

The Dr. Infrared units look a bit more like the King ones,.and can run an external thermostat. https://a.co/d/akQFneg

Qmark seems to be another decent brand.

 

[rich_kildow]

Don't do anything yet! CALL the manufacturer and tell them what happened……. They need to know this to prevent future fires or death.
Maybe these heaters need to have a National recall due to a failing heating element and unless these issues are reported the manufacturer thinks everything is fine.

TIP! Try to get an email address and document this problem.…… This issue could get very interesting.

I will be sending some emails and making calls tomorrow. I'll keep this thread up to speed with what I hear.

 

[whateg01]

The dyna glo I have uses tubular elements. I have had one element open up so I replaced the heater with a like model, 5000W.

There are other brands that are likely the same inside.

 

[theoldwizard1]

I know they make 50 amp GFCI dual poles for this panel, and I'm not above the $200 investment. If it gives me some peace of mind going with another electric heater like this.

Not certain a GFCI would help. They detect current "leakage" to ground.

I would try a 40A breaker if you can find one.

 

[whateg01]

I will be sending some emails and making calls tomorrow. I'll keep this thread up to speed with what I hear.

Their verbiage about having to be installed exactly right tells me that you aren't going to gain anything by contacting them. You'll have to jump through a bunch of hoops to get them to even consider doing anything and then it'll cost you more to deal with it than a replacement heater. Maybe I'm wrong.

 

[whateg01]

Not certain a GFCI would help. They detect current "leakage" to ground.

I would try a 40A breaker if you can find one.

If it shorted to the heat sink, which should be grounded, it should trip a GFCI. If it had shorted out to another spot on the element itself then it wouldn't detect it.

 

[theoldwizard1]

I would try a 40A breaker if you can find one.

I don't know about breakers, but fuses have to exceed their rating by A LOT for some period of time before blowing. Like 100% for multiple seconds.

 

[sparky 1971]

I would try a 40A breaker if you can find one.

40 amp breakers are available anywhere, but 10,000 watts/240 volts=41.7 amps.

 

[theoldwizard1]

40 amp breakers are available anywhere, but 10,000 watts/240 volts=41.7 amps.

You think they are calibrated that close ?

 

[whateg01]

You think they are calibrated that close ?

This is the reason building codes exist

 

[sparky 1971]

You think they are calibrated that close ?

It might run just fine for a long time on a 40, maybe forever but I doubt it. It might also last two minutes before it trips.

 

[rooster59]

I would think it like this- cheap heater $600- tried to burn garage down. King heater- $1200- not try to burn garage down. It’s not really $1200, it’s a $600 premium for a better heater, lasts longer, and doesn’t try to burn things down.

 

[fitter30]

10 kw pulls 41.7 amp + fan motor and controls. One element could of failed and melted going to ground pulling 20.5 amps or less where it broke and melted. Elements are nickel- chromium resistance heater core insulated by magnesium oxide then a steel case and aluminum fins. Electric water heaters use type of element with no fins. Most failures the core just breaks and stops heating.

 

[rich_kildow]

I would think it like this- cheap heater $600- tried to burn garage down. King heater- $1200- not try to burn garage down. It’s not really $1200, it’s a $600 premium for a better heater, lasts longer, and doesn’t try to burn things down.

You're not wrong at all. I like electric as I only heat when I need to work out there. As soon as I hit the $1000+ mark, thinks like Reznor or Modine propane heaters are suddenly more competitive. I'm not at all opposed to spending money, just want to make the best choice for my dollar.

Besides being USA made and carrying a premium price, what makes King that much better? Any additional safety features?

I'm liking the look of the Qmark (Marley/Dimplex) heaters which also look to be use made.

 

[dscheidt]

You're not wrong at all. I like electric as I only heat when I need to work out there. As soon as I hit the $1000+ mark, thinks like Reznor or Modine propane heaters are suddenly more competitive. I'm not at all opposed to spending money, just want to make the best choice for my dollar.

Besides being USA made and carrying a premium price, what makes King that much better? Any additional safety features?

I'm liking the look of the Qmark (Marley/Dimplex) heaters which also look to be use made.

If you’re staying electric, a split will be a lot cheaper to run. Plus ac…

 

[Chuckster in NJ]

I would think it like this- cheap heater $600- tried to burn garage down. King heater- $1200- not try to burn garage down. It’s not really $1200, it’s a $600 premium for a better heater, lasts longer, and doesn’t try to burn things down.

I agree 100% with you on your logic and I personally live by it on purchasing equipment and parts, however the man purchased a UL approved unit that he spent his hard earned money (possibly all that he could afford) on trusting that it was a safe heater.……… "IF" he "cheated" manufacturer Installation instructions I would would be the first to say "Oh Well, education is expensive and OP should have read the installation instructions" but in this case it was a cheap inferior part that needs to be addressed BEFORE there is loss of property and or life on a "now known and documented" issue.

BTW! I have seen a lot of POS things that has a "UL label" on it and wonder how it met a testing lab approval……. In OP's situation at least he is dealing with an American company and hopefully he has a positive outcome or at least the company recalls these heaters.

 

[whateg01]

I agree 100% with you on your logic and I personally live by it on purchasing equipment and parts, however the man purchased a UL approved unit that he spent his hard earned money (possibly all that he could afford) on trusting that it was a safe heater.……… "IF" he "cheated" manufacturer Installation instructions I would would be the first to say "Oh Well, education is expensive and OP should have read the installation instructions" but in this case it was a cheap inferior part that needs to be addressed BEFORE there is loss of property and or life on a "now known and documented" issue.

Except, from the manufacturer's point of view there was not an issue. There was almost an issue. Or there was almost potentially an issue. But nobody's house burned down and nobody died.

BTW! I have seen a lot of POS things that has a "UL label" on it and wonder how it met a testing lab approval……. In OP's situation at least he is dealing with an American company and hopefully he has a positive outcome or at least the company recalls these heaters.

As I recall, please are allowed to self-certify at least in certain instances. So stating that something is UL compliant could potentially just mean that the manufacturer believes all of their components meet the criteria that UL has laid out. Of course, the FAA allowed Boeing to self certify as well...

 

[mm08822]

You think they are calibrated that close ?

You forgot about code?
A continuous load needs to be fed with conductors and cb @ 125%.......50A in this case. The heater element load is already at 41.67A+ fan + controller. What if the supplied voltage is 245V........42.5A+.

What is your rationale anyway to lower the cb value? If 1 of the elements is arcing due to a bad connection, it will lower the overall current drawn.

 

[mm08822]

I don't know about breakers, but fuses have to exceed their rating by A LOT for some period of time before blowing. Like 100% for multiple seconds.

It all depends on the fuse element rating. But one size does not fit all. The same can be said for certain cb's.