15A fuses

[ERD50]

....

Anyway, the circuit breakers are Siemens ARC.

....

Ahhhh, from "fuse" to "Circuit breaker" to "ARC".... that's a horse of a different (shade of) color!

Nuisance tripping is far more common with those types, and be caused by many different things besides the total amps.

It could even be something other than the heaters. The arc suppression won't kick in below 5A draw. So if something else that is low current is creating an ARC-like condition, the heater would raise the current above 5A, and the ARC breaker would then sense the other thing (that it was ignoring because current was too low).



See p14: http://structuretech.com/wp-content/uploads/2016/02/AFCI-Tripping-NEMA-Compatibility.pdf

.... I am going to use the heaters normally and see if the circuit breakers continue to trip. .

What is "normally"? How else were you using them?

-ERD50

 

[retire-early]

What is "normally"? How else were you using them?

Meaning I am not going to obsess about the use of them.
After the circuit breaker tripped last night, I didn't turn on the space heater again which is silly since why buy one if I am not going to use it?

 

[ERD50]

Meaning I am not going to obsess about the use of them.
After the circuit breaker tripped last night, I didn't turn on the space heater again which is silly since why buy one if I am not going to use it?

No, that's not silly, it's prudent. The breaker tripping could be for a good reason and it could be related to the heater or your house wiring. Or it could be a false alarm.

You've got a licensed electrician on the way. If I were you, I would not use those space heaters (at least on those circuits) until he has checked it out.

And someone else asked - you are using two space heaters this time of year? Seems kinda odd, but maybe you just don't want to run the whole house furnace if it is just a bit chilly in a couple rooms?

-ERD50

 

[l8_apex]

Google about your AFCI breakers: "siemens afci breaker tripping" and you'll start to get some answers.

buy a watt meter to measure power draw at the outlet. https://www.amazon.com/Electricity-...jbGlja1JlZGlyZWN0JmRvTm90TG9nQ2xpY2s9dHJ1ZQ==

Then you'll know if it's the power consumption or the circuit breaker that's the root cause. Ask the electrician if there is a less sensitive type of breaker that can be installed. I have an AFCI that caused me problems. I replaced with the updated version, but certain loads (vacuum) cause it to trip still.

 

[NW-Bound]

Ahhhh, from "fuse" to "Circuit breaker" to "ARC".... that's a horse of a different (shade of) color!

Nuisance tripping is far more common with those types, and be caused by many different things besides the total amps.

It could even be something other than the heaters. The arc suppression won't kick in below 5A draw. So if something else that is low current is creating an ARC-like condition, the heater would raise the current above 5A, and the ARC breaker would then sense the other thing (that it was ignoring because current was too low).

See p14: http://structuretech.com/wp-content/uploads/2016/02/AFCI-Tripping-NEMA-Compatibility.pdf

-ERD50

Google about your AFCI breakers: "siemens afci breaker tripping" and you'll start to get some answers.

...I have an AFCI that caused me problems. I replaced with the updated version, but certain loads (vacuum) cause it to trip still.

My houses were built before AFCI (arc-fault circuit interrupter) became a requirement. Hence, I have no experience with them, but it appears that this is not yet a mature product that is as reliable as it should be, even though its intended function is highly useful to prevent fires.

The other side of nuisance tripping is an AFCI that does not trip, despite multiple attempts to cause arcing.

 

[ERD50]

My houses were built before AFCI (arc-fault circuit interrupter) became a requirement. Hence, I have no experience with them, but it appears that this is not yet a mature product that is as reliable as it should be, even though its intended function is highly useful to prevent fires.

The other side of nuisance tripping is an AFCI that does not trip, despite multiple attempts to cause arcing. ....

I am going to make a semi-educated guess about why it didn't trip. Typically, a loose connection in a home that would start a fire would be something that was working fine for a while, then loosened as it aged.

Think about a wire being connected, but a poor connection versus totally loose like in the video. I think you'd get an arc across the poor connection as the 50/60 Hz voltage rose (along the sine wave), and then it would extinguish as the voltage dropped near the zero crossing point. This would produce a discontinuity in the current waveform, with a high-frequency component as it arc over, and then extinguishes on the down-side of the sine wave. That would be high-frequency, but with a 50/60 Hz repetition rate (edit/add: actually, a 100/120Hz rep rate, as you'd get two arcs per cycle, a 'make' and a 'break' - further edit! or is it four per cycle? A make and then break on each half-cycle?).

So I'm guessing that the signal detectors in those AFC breakers are looking for that 50/60 Hz rep rate as well, and he really doesn't get that with his test. But he still makes a good point that his failure could happen, it could start a fire, and the ARC isn't responding.

IIRC, you posted some videos of arcs on solar panels on the DC side. Those demonstrated how dangerous DC can be, as w/o the 50/60 Hz return to zero to break the arc, the DC arc just keeps going. Somewhat related to this.

Maybe later I'll finally get around to starting another thread. I think I read on this forum about an electronic monitoring service that some insurance companies were offering for free. I signed up, it's a box that monitors parameters on your line, and sends some data to the cloud for non-real-time analysis by big computers. So far, no fault alarms, but it has reported a couple short brown-outs and a couple power surges (at least one of those I also detected with my eyes/ears). It said those were rare enough to not be considered a problem. I've been tempted to test it like this guy did, and see if I get an alarm report. The box and 3 years service was free.

-ERD50

 

[NW-Bound]

I read the comments to the YouTube video that I shared.

Most of the comments were asinine. They said that what the guy simulated was a serial arc, and that the AFCI would trip if it were a parallel arc. And the video poster had to reply time and time again that a parallel arc, which is a short, would immediately trip a regular breaker. You don't need a fancy AFCI to detect a short.

Still, one commenter said that he tried the same thing with his AFCI, and the serial arc tripped it.

Taken at face value, it showed that there were defective or ineffectual AFCIs being offered on the market. How does the consumer know to choose?

 

[Time2]

You said the heaters are 1500 watt, if that is correct, you are getting close to the limit of the breakers, especially if there is anything else connected on that breaker.

There are several types of breakers, some use magnetic qualities and some use thermal qualities.

Simplified: with magnetic breakers, the one second trip time can vary from 3 times to 20 times the rating on the breaker. So 30 amps to 300 amps for a 15 amp breaker to trip in one second.

A thermal breaker can go as long as 1000 seconds with 2 times the breakers rated capacity. (15 amp breaker---30 amps for 17 minutes)
It is possible a poor connection to or in the breaker will cause heat and this heat will add to the normally developed heat in the breaker.
By to, I mean the screw terminal on the breaker, check that it is tight. By in, I mean there is a poor connection inside the breaker, and it needs replacement. As said above, do not put in a breaker with a higher amp rating. The Breaker protects the wiring in the walls from over heating.

 

[CRLLS]

One comment I have not seen posted yet. Inexpensive heaters may contain a bimetallic thermal switch. They open and close the circuit to regulate the room temperature. If your heater have this type of control, it is normal for the switch to arc internally when opening. i.e. it has reached the desired temperature. This can be confirmed with an old fashioned AM radio. Tune any station and wait for the temperature to reach the desired setting. There will be a long raspy noise when the switch begins to open, usually lasting a few seconds. This indicates arcing between the contacts in the switch which is normal for this type of temperature control. This might be the cause of a AFCI tripping. If it is, the fix is to replace the AFCI with a different design breaker or replace the heaters with ones with electronic controls.

 

[Time2]

Did I miss the fact that the OP has AFCI breakers?

 

[ERD50]

You said the heaters are 1500 watt, if that is correct, you are getting close to the limit of the breakers, especially if there is anything else connected on that breaker.

There are several types of breakers, some use magnetic qualities and some use thermal qualities.

Simplified: with magnetic breakers, the one second trip time can vary from 3 times to 20 times the rating on the breaker. So 30 amps to 300 amps for a 15 amp breaker to trip in one second.

A thermal breaker can go as long as 1000 seconds with 2 times the breakers rated capacity. (15 amp breaker---30 amps for 17 minutes)
It is possible a poor connection to or in the breaker will cause heat and this heat will add to the normally developed heat in the breaker.
By to, I mean the screw terminal on the breaker, check that it is tight. By in, I mean there is a poor connection inside the breaker, and it needs replacement. As said above, do not put in a breaker with a higher amp rating. The Breaker protects the wiring in the walls from over heating.

Good information - I just want to expand on this statement: "some use magnetic qualities and some use thermal qualities" - I've done some deep dives into this in the past few years, and AFAIK, all the typical home circuit breakers utilize both magnetic and thermal mechanisms.

As you say, the thermal will respond (but takes significant time) to the kinds of overloads you can see from too many loads on one circuit, or some faulty device that is drawing high current but isn't exhibiting a direct short.

The magnetic is near instantaneous, but only responds to very high currents, like a direct short. Both are needed, and the old fashioned fuses I think provided this, because that thin element responded very fast to these super-high short currents, and blew out. The circuit breaker has a much higher thermal mass and inertia, so needs a second electro-(magnetic) mechanism.

-ERD50

 

[ERD50]

Did I miss the fact that the OP has AFCI breakers?

Post #25. Yes, a lot of important details have been left out by OP, even after being requested. So we are just discussing general principles for the 'fun' of it.

And it's not even clear if the electrician actually replaced the breakers (with gen2?), or just commented on it.

-ERD50

 

[mountainsoft]

The 15A fuses in the fuse box are tripping, and it seems that space heaters are causing this.

I don't even have the heaters set on High.

How old are the heaters? Most space heaters have fans in them. If the heater is old the fans could be wearing out, increasing the current draw. You're already around 12.5 amps for a 1500 watt heater, it wouldn't take much more to trip a 15 amp breaker. A few 60 watt light bulbs and the startup current of an old fan motor would do it, especially if the breaker is weak too.

By the way, it's not just old breakers that get weak. I recently bought a brand new breaker that would nuisance trip every time I turned a saw on. I exchanged it for another breaker and the problem went away.

 

[Time2]

Post #25. Yes, a lot of important details have been left out by OP, even after being requested. So we are just discussing general principles for the 'fun' of it.

And it's not even clear if the electrician actually replaced the breakers (with gen2?), or just commented on it.

-ERD50

Ok, great, I was questioning the validity of your post, #31, but, now with AFCIs, it all makes more sense!

 

[calmloki]

Last year we came back south and found some outlet circuits not working. Complicated matters because I forgot that some of the outlets are switched on the upper outlet and i didn't have the switch on. Anyway, after tracking and swapping AFCIs I finally decided the AFCI had failed. This with us gone and very little load on the circuit. Reluctantly changed it and all has been well since. My guess was that we got some sort of bad electricity delivered to the house - it's not uncommon for the switches up by the transformers on the poles to throw, leaving portions of the town dark for a few hours.

Had to open it up to see what i could see, only thing I remember looking odd/bad was a small coil that looked like its outer clear insulating cover was brown from heat. For the cost of the breaker there was at least a satisfying level of complexity to the part.

 

[NW-Bound]

^^^ Thanks for sharing the photos.

Not having one, nor disassembling one, I wonder what is inside these $50 AFCI, though I expect them to have some electronics in order to do a spectral analysis of the load current.

It looks like these don't have to cost $50. Compared to the $5 old-fashioned circuit breaker, I would generously give them another $10 for the electronics.

 

[ERD50]

^^^ Thanks for sharing the photos.

Not having one, nor disassembling one, I wonder what is inside these $50 AFCI, though I expect them to have some electronics in order to do a spectral analysis of the load current.

It looks like these don't have to cost $50. Compared to the $5 old-fashioned circuit breaker, I would generously give them another $10 for the electronics.

I may spend a bit more time looking for a schematic later. I did find a block diagram explanation, and I'm guessing it's relatively simple - some filters, amplifiers, and comparators. But I guess we are not too far from being able to have a DSP/uC built into these - or maybe a more sophisticated one in the panel, monitoring every circuit?

-ERD50

 

[ERD50]

Miraculously a licensed electrician came to my house. ...

I am going to use the heaters normally and see if the circuit breakers continue to trip.

.

It's been two days since electrician showed up. What did he do? Are the breakers still tripping?

-ERD50

 

[OldShooter]

... It looks like these don't have to cost $50. Compared to the $5 old-fashioned circuit breaker, I would generously give them another $10 for the electronics.

Having participated in a couple of national standards writing activities, I can testify that industry participation goals are first to protect existing product lines and then to sell something new and more expensive.

I'd bet a $100 bill that the arc-fault breaker requirement was proposed and sold by industry whether there was a statistical safety case for it or not. Similarly, test and certification requirements for the devices were probably proposed by industry with an eye towards creating barriers to entry by new participants.

Once the requirement and the barriers are there, an oligopoly can control pricing by price signaling a la the airline industry.

 

[NW-Bound]

I may spend a bit more time looking for a schematic later. I did find a block diagram explanation, and I'm guessing it's relatively simple - some filters, amplifiers, and comparators. But I guess we are not too far from being able to have a DSP/uC built into these - or maybe a more sophisticated one in the panel, monitoring every circuit?

-ERD50

Two years ago, I bought some ARM microcontrollers to play with (and to build a battery management system for my lithium battery projects).

These microcontrollers are way more powerful than the IBM PC AT, with a 32-bit CPU instead of 16-bit, clock speed of 48 MHz instead of 6 MHz, tons of built-in memory for code and data, a built-in A/D converter with multiplexing circuit and capable of 1 million samples/second.

I paid less than $1/each retail price for a lot of 10. Maybe it was $0.75/each.

These chips are about the size of the chip shown in calmloki's photo. They don't even need a crystal for a clock; the clock generator is built-in.

 

[ERD50]

Two years ago, I bought some ARM microcontrollers to play with (and to build a battery management system for my lithium battery projects).

These microcontrollers are way more powerful than the IBM PC AT, with a 32-bit CPU instead of 16-bit, clock speed of 48 MHz instead of 6 MHz, tons of built-in memory for code and data, a built-in A/D converter with multiplexing circuit and capable of 1 million samples/second.

I paid less than $1/each retail price for a lot of 10. Maybe it was $0.75/each.

These chips are about the size of the chip shown in calmloki's photo. They don't even need a crystal for a clock; the clock generator is built-in.

Yes, they could certainly have a microcontroller built in. It was really the DSP type functions I was thinking more about. Maybe those are cheap now too, or maybe these cheap uC can do DSP, I don't know.

It's funny, I was thinking about making a post on a more tech based forum that I follow a bit. About how today, it often seems the simplest/cheapest way to do something is with something that actually has a lot of complexity built in. By the time you even think about putting in a couple comparators with hysteresis into a circuit like that, you might as well go with the microcontrollers with built in ADC - you can vary the trigger level and hysteresis, and do some filtering all under program control, no added hardware.

And I was looking at a cheap/easy way to monitor the position of a float in my sump pit, and it might be that the simplest way is to use this little board that measures the reflection times of an IR LED (they also make them that use ultrasonic waves, but they spread out faster, and are more affected by the nearby environment). The complex is now simple. It's a different way to think about things.

-ERD50

 

[NW-Bound]

Yes, they could certainly have a microcontroller built in. It was really the DSP type functions I was thinking more about. Maybe those are cheap now too, or maybe these cheap uC can do DSP, I don't know.

DSPs are just specialized CPUs to do simple repetitive algorithms such as FFT (Fast Fourier Transform) faster than general purpose CPUs. They are not more expensive than regular CPUs. Regular CPUs can be programmed to do DSP functions too.

The ARM microcontrollers have powerful RISC CPU cores that are in the same family as the ARM chips that go into notebooks and laptops. They are not the same as the 8051 microcontroller of yesteryear that was inside sprinkler timers and such simple electronic devices. They are used in car ECUs. Some microcontrollers now have floating-point capabilities, but they cost a few dollars, not 75c.

 

[NW-Bound]

One comment I have not seen posted yet. Inexpensive heaters may contain a bimetallic thermal switch. They open and close the circuit to regulate the room temperature. If your heater have this type of control, it is normal for the switch to arc internally when opening. i.e. it has reached the desired temperature. This can be confirmed with an old fashioned AM radio. Tune any station and wait for the temperature to reach the desired setting. There will be a long raspy noise when the switch begins to open, usually lasting a few seconds. This indicates arcing between the contacts in the switch which is normal for this type of temperature control. This might be the cause of a AFCI tripping. If it is, the fix is to replace the AFCI with a different design breaker or replace the heaters with ones with electronic controls.

This is a highly relevant comment. I did not know the break time of a bimetallic switch could be as long as a few seconds. If so, the arc between the thermostat contacts is indistinguishable from the arc at a loose wiring terminal of a wall outlet, for example.

Hmmm... This would be problematic for any devices that use a mechanical bimetallic thermostat. Virtually every small heating device uses this simple and cheap thermostat, such as clothes irons, electric kettles, electric woks, toaster ovens, portable burners, etc...

Electric water heaters also use a bimetallic thermostat. However, due to the higher current and voltage, their design is such that there is a snap action when they click on/off. You can hear and feel this when you rotate the adjustment screw. I have a newer water heater that uses electronic control, and it does not use a bimetallic thermostat.

 

[wolf]

Your 15 amp circuit breakers are simply just doing their job. Each of your 15 amp circuits will supply a max of 1800 watts of power. You are plugging in a 1500 watt load into a circuit that more than likely already has some power being consumed by other electrical loads lights, tv’s etc. It simply overloads the circuit and the breaker opens the circuit to prevent further damage. There is no
Need to start replacing parts. Lighten the load on the circuit or get smaller wattage heaters.

+1. 15 amp circuit. Also, I think, (ERD50) comment may be correct also.
Just because you plug 2nd heater, different outlet/room, it may be
on the same circuit.

 

[Retired Expat]

Verify that the wire in the wall is #12 solid copper and the wires are connected to the outlet screw terminals well and not just the push connectors. Take your heater and plug it in as close to your circuit breaker panel and see if it still trips out?