15A fuses

[papaof2]

Have you verified they are not the same circuit? Different rooms can share a circuit, it depends on the layout and electrical runs.



And what else is on the circuit with the heater? The combinations could push it past the trip point.

You didn't answer the Q about "how many are tripping?". Two different circuits tripping, with two heaters?

Exactly what type of space heater? Again, most heaters will draw the same watts/amps on "LOW" as they do on "HIGH" - it will just run for less time.

Unsafe is overloading a circuit. While it is possible your circuit breakers are over sensitive, I'd rule out an overload first.

In the OP you said they "don't immediately trip." That would only happen if you had a direct short. A typical overload condition can take minutes, even hours to trip.

-ERD50

UNLESS you've verified which breaker EVERY outlet is on - plug a light into the outlet then turn the breaker off and back on, phones or yelling through the house to coordinate - you don't KNOW that the outlets in different rooms are on different breakers - or that the breaker hasn't been multi-tapped (NOT to code) and the breaker for the dishwasher is also feeding the outlets in one or more rooms. This house (almost 50 years old) has had a lot of "need to add..." from previous owners and I spent several days mapping the lights and outlets to their respective breakers. Here are a couple of bad examples of what I found:

Garage lights, garage door openers, garage inside wall outlet, outside lights over driveway, laundry room lights & outlets (including freezer), screened porch, corner floodlight over lower drive

Disposal, family room and kitchen lights, master bedroom closet, outlet by master bedroom closet

If a heater was plugged into that "outlet by master bedroom closet" and someone turned on the garbage disposal, you'd probably be very close to the trip level of that breaker. Even more likely to trip if the heater is in the laundry room, the freezer is in its defrost cycle and someone opens or closes a garage door.

Do you KNOW how things are wired?

 

[street]

Do you have a clamp around Amp meter? Amp meters are a very handy instrument to have. Over load sounds like the problem and any amp meter would tell you the story.
Good Luck.

 

[DougJohnson]

Verify that the wire in the wall is #12 solid copper ...

15 amp breakers only need 14 gauge wire.
-- Doug

 

[NoEZmoney]

If you're still running fuses, I'd suggest you invest in switching to breakers as that would bring you up to code. Get with a licensed electrician who can install a new board and get you going. It's safer.

 

[ERD50]

Originally Posted by Retired Expat View Post
Verify that the wire in the wall is #12 solid copper ...

15 amp breakers only need 14 gauge wire.
-- Doug

Correct 14 Gauge for 15A; 12 gauge for 20A. Long runs may require a step up in size. NOTE: for wire gauge the smaller # is a larger wire. I think it had something to do with the number of times it was thinned out in the old days.

If you're still running fuses, I'd suggest you invest in switching to breakers as that would bring you up to code. Get with a licensed electrician who can install a new board and get you going. It's safer.

See posts #5 and #26

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

Not sure the OP is still involved though.

-ERD50

 

[2177V]

Suggest using the kitchen outlets because cooking in the kitchen can draw higher amps than bedrooms and living rooms. If necessary use a 12 gauge extension cord. 10 gauge if longer than 50 feet.

 

[sengsational]

A house inspector told me that if any of the breakers in the panel didn't match, he'd not "pass" the panel. He said any changes required everything to be replaced. I called BS.

 

[seraphim]

Heaters pull about 12.5 amps and can spike. Putting 2 on the same circuit will trip the breaker.

 

[travelover]

Wow, 58 posts on a blown circuit breaker. Slow news week.

 

[doneat54]

Space heaters are not the greatest way to go, for several reasons. If you are tripping a breaker, there is likely a fault in the cord or the outlet, causing a voltage drop and raising the current. The byproduct is heat, which further degrades the connections. Anywhere along the wiring that has a connection, there is a little voltage drop under a load like that. You might be heating up an outlet you are not even using, because the current passes through it along the way to that heater. I chased one of those down at a friend's house and it was damn scary when I got the cover off and found cooked wire and insulation.

FYI, voltage drops won't cause a rise in current. In fact, as they are added resitance, they actually lower the overall current and corrosion type drops that you describe are not likely to be the cause of tripping a breaker. But everything else you said is correct, and dangerous. These "drops" allow heat to build up at the location, increase corrosion, then create more localized heat. Snowball effect. I deal with this a lot in my vintage cars with 6 volt systems.


To the OP, if all the wattages/currents check out, replace the breaker. They are cheap and designed to trip "low" when they fail.

 

[ERD50]

Wow, 58 posts on a blown circuit breaker. Slow news week.

And OP is AOL. Hope the house didn't burn down.

Anyhow, thread would likely be a lot shorter if OP gave out some info. What did come out was incomplete and dribbled out over time.

I am curious how this is going.

-ERD50

 

[CRLLS]

FYI, voltage drops won't cause a rise in current. In fact, as they are added resitance, they actually lower the overall current and corrosion type drops that you describe are not likely to be the cause of tripping a breaker. But everything else you said is correct, and dangerous. These "drops" allow heat to build up at the location, increase corrosion, then create more localized heat. Snowball effect. I deal with this a lot in my vintage cars with 6 volt systems.


To the OP, if all the wattages/currents check out, replace the breaker. They are cheap and designed to trip "low" when they fail.

I agree that voltage drops will not "generally" cause a breaker to trip. I do want to comment on your "voltage drops wont cause a rise in current." This is not an absolute. Many electronic devices today have a switch mode power supply. These devices (TV's, Stereo systems, computers, etc) increase current load as the line voltage drops, virtually linearly. A 10% drop in line voltage causes about a 10% rise in current.

I do hope that the OP has resolved their problem by now.

 

[Time2]

I agree that voltage drops will not "generally" cause a breaker to trip. I do want to comment on your "voltage drops wont cause a rise in current." This is not an absolute. Many electronic devices today have a switch mode power supply. These devices (TV's, Stereo systems, computers, etc) increase current load as the line voltage drops, virtually linearly. A 10% drop in line voltage causes about a 10% rise in current.

I do hope that the OP has resolved their problem by now.

While, "I agree that voltage drops will not "generally" cause a breaker to trip".
If the voltage drop is enough that it will cause a motor to not start, then current caused by a locked rotor will be high and could cause a breaker to open. Example; air compressor, freezer, especially if it has just had a cooling run and is trying to restart.

 

[Bruno]

If you can borrow a amp probe check to see if you have any current flow on the wire at the breaker and then check it when the heater is plug in.

 

[CRLLS]

While, "I agree that voltage drops will not "generally" cause a breaker to trip".
If the voltage drop is enough that it will cause a motor to not start, then current caused by a locked rotor will be high and could cause a breaker to open. Example; air compressor, freezer, especially if it has just had a cooling run and is trying to restart.

True too. That is why I emphasized the word "generally". There are many other devices that have start-up current noticeably higher than their operating current (a.k.a. rated current during normal operation). Depending on the duration of such an event, it could easily trip a breaker. Many if not all breakers and fuses have IT ratings (Current*time) for such events. The graph of this rating may not necessarily be a linear graph. A motor's locked rotor current would cause the duration much longer than "normal" and would/should trip the breaker.

 

[retire-early]

I called Siemens technical support last Wednesday.
They actually have a toll free number for consumers to call.
The tech support guy was in Pennsylvania for me.

Anyway, he actually admitted that the AFC breakers can be problematic.


He suggested buying the Minuteman MMS110 surge protector.
I bought two.

I am using one for the refrigerator which started to trip the circuit breaker after I asked the electrician to change QAF for QAF2 with all else unchanged.

I also had a Belkins one-outlet surge protector F9H100-CW that I bought a couple of years ago.
I am using it for the laser printer. So far so good. No more trips from the laser printer causing circuit breaker to trip.
One of the reviews on Amazon mentioned using it to prevent his AFCI circuit breaker from tripping when the treadmill starts.

 

[l8_apex]

Retire - thanks for posting the update. I've ordered a single outlet surge protector and I'll see if that lets me use my vacuum in my outlet that has an AFCI breaker. I hadn't heard of that being a solution, hopefully it will work for my use case.

 

[OldShooter]

... That is exactly my case. Both are on the same GFI, even though they are on opposite sides of the house.

Me, too. Outlets by front and back doors are controlled by a GFI outlet in the basement. A real puzzle until I finally figured it out.

I am just writing a spec for a new house and it says that outlet-style GFIs may used only if they are proximate to other outlets they protect, like in the kitchen or bath. Scattered GFI-protected outlets, like outside, must run from a well-marked GFI breaker(s) in the entry panel.

 

[retire-early]

Retire - thanks for posting the update. I've ordered a single outlet surge protector and I'll see if that lets me use my vacuum in my outlet that has an AFCI breaker. I hadn't heard of that being a solution, hopefully it will work for my use case.

Unfortunately, I wrote too soon.
The good news is that the laser printer hasn't tripped the AFCI breaker since I put in the surge protector.
However, the AFCI breaker for the refrigerator, which never tripped before, tripped again last night.
The refrigerator had a surge protector.
I thought it would be a good idea to replace all the QAF with the QAF2 since the electrician was here.
The phrase "don't fix what isn't broken" definitely applies to AFCI breakers.
Nothing has changed except the breaker.
For some reason the original AFCI breaker never detected an arc fault, but the new one does. SIGH.
If I leave on vacation, it is very likely I will come back to a refrigerator with spoiled food inside.

 

[travelover]

Unfortunately, I wrote too soon.
The good news is that the laser printer hasn't tripped the AFCI breaker since I put in the surge protector.
However, the AFCI breaker for the refrigerator, which never tripped before, tripped again last night.
The refrigerator had a surge protector.
I thought it would be a good idea to replace all the QAF with the QAF2 since the electrician was here.
The phrase "don't fix what isn't broken" definitely applies to AFCI breakers.
Nothing has changed except the breaker.
For some reason the original AFCI breaker never detected an arc fault, but the new one does. SIGH.
If I leave on vacation, it is very likely I will come back to a refrigerator with spoiled food inside.

I have a circuit in my garage that just can't get along with an AFCI breaker, so I just replaced it with a GFCI breaker. It is a ten minute job. The risk of a arc generated fire is tiny - originally they were only used in bedrooms.