We had a GE microwave that was about twenty years old. Latterly, it started blowing the fuse if i ever ran it with the (gas!) oven on. i figured it had a problem with power consumption.

My neighbor bought all new samsung appliances and said i could take her perfect working GE microwave which is about fifteen years newer than mine was. So i switched my old one for the neighbors newer one.

Now the fuse blows every time i turn the microwave on!!

Besides, of course, only running mine at half power, is there anything I can do to stop the fuse blowing please?

On 10/23/2019 6:52 PM, DManzaluni wrote:
We had a GE microwave that was about twenty years old. Latterly, it started blowing the fuse if i ever ran it with the (gas!) oven on. i figured it had a problem with power consumption.

My neighbor bought all new samsung appliances and said i could take her perfect working GE microwave which is about fifteen years newer than mine was. So i switched my old one for the neighbors newer one.

Now the fuse blows every time i turn the microwave on!!

Besides, of course, only running mine at half power, is there anything I can do to stop the fuse blowing please?


I assume you mean a circuit breaker. Maybe it is bad.

On Wednesday, October 23, 2019 at 7:18:26 PM UTC-4, Frank wrote:
On 10/23/2019 6:52 PM, DManzaluni wrote:
We had a GE microwave that was about twenty years old. Latterly, it started blowing the fuse if i ever ran it with the (gas!) oven on. i figured it had a problem with power consumption.

My neighbor bought all new samsung appliances and said i could take her perfect working GE microwave which is about fifteen years newer than mine was. So i switched my old one for the neighbors newer one.

Now the fuse blows every time i turn the microwave on!!

Besides, of course, only running mine at half power, is there anything I can do to stop the fuse blowing please?


I assume you mean a circuit breaker. Maybe it is bad.

Could be. I would start by adding up whatever is on that circuit when it trips and see how it compares to the breaker rating.

In article ,
DManzaluni wrote:

We had a GE microwave that was about twenty years old. Latterly, it started
blowing the fuse if i ever ran it with the (gas!) oven on. i figured it had
a problem with power consumption.

My neighbor bought all new samsung appliances and said i could take her
perfect working GE microwave which is about fifteen years newer than mine
was. So i switched my old one for the neighbors newer one.

Now the fuse blows every time i turn the microwave on!!

Besides, of course, only running mine at half power, is there anything I can
do to stop the fuse blowing please?

DM-

Are you using fuses or circuit breakers? How many Amps? How many
Volts? How many Watts is the microwave?

If a circuit breaker, it is possible you have one defective that blows
at less than rated current.

You might just have a defective Microwave. Or you might be using a
high-power coffee maker at the same time on the same circuit.

Note that a microwave running half power, may be running full power half
the time.

I am running an 1100 Watt GE Microwave that has no trouble on a 120 Volt
20 Amp circuit breaker.

My circuit breaker is 120V * 20A = 2.4KW. An internal Microwave label
says 1.5KW, which is 120V * 12.5A. If yours is the same, you should get
by with a 15A breaker or fuse @120VAC with little else on the circuit.

Fred

Thanks for this guys but it hadn't struck me that the circuit breaker might be bad. It makes perfect sense. the only other possibility is that whoever wired the breaker box put too much on that circuit, which is something about which we wondered ever since we moved in.

This circuit breaker plainly can't take whatever is on the circuit, - while the probability is that the newer GE Profile microwave uses LESS power than the ancient GE Profile, not more!

How difficult is it to change an individual circuit breaker in an 8 fuse box please? And can i test whether is (and one other CB which is also blowing far too often) is performing to specs? this is the original CB box that has been in the flat since the building went up about 40 years ago.

6 of the fuses are 20 amp breakers, while the one which blows constantly is a 15 amp one! And although I have a theory that fuse boxes tend to have been installed by competent licensed electricians when the building went Various appliances in the kitchen (but not the fridge or dishwasher or washing machine), including the oven, all wall socket powered lights and 23 pieces of TV/stereo equipment in the living room, all wall socket powered lights, stereo and television in the bedroom etc!!

I have always wondered whether doing all this on one circuit breaker was asking-for-trouble. With all the stereos, TVs, lights etc , that 15 amp CB would ALWAYS blow when i turned the old microwave on when the oven was on. Now it blows even when the oven isn't on.

(The microwave calls itself 1.58 kilowatts)

On Thu, 24 Oct 2019 07:22:00 -0700 (PDT), DManzaluni
wrote:

Thanks for this guys but it hadn't struck me that the circuit breaker might be bad. It makes perfect sense. the only other possibility is that whoever wired the breaker box put too much on that circuit, which is something about which we wondered ever since we moved in.

This circuit breaker plainly can't take whatever is on the circuit, - while the probability is that the newer GE Profile microwave uses LESS power than the ancient GE Profile, not more!

How difficult is it to change an individual circuit breaker in an 8 fuse box please? And can i test whether is (and one other CB which is also blowing far too often) is performing to specs? this is the original CB box that has been in the flat since the building went up about 40 years ago.

6 of the fuses are 20 amp breakers, while the one which blows constantly is a 15 amp one! And although I have a theory that fuse boxes tend to have been installed by competent licensed electricians when the building went Various appliances in the kitchen (but not the fridge or dishwasher or washing machine), including the oven, all wall socket powered lights and 23 pieces of TV/stereo equipment in the living room, all wall socket powered lights, stereo and television in the bedroom etc!!

I have always wondered whether doing all this on one circuit breaker was asking-for-trouble. With all the stereos, TVs, lights etc , that 15 amp CB would ALWAYS blow when i turned the old microwave on when the oven was on. Now it blows even when the oven isn't on.

(The microwave calls itself 1.58 kilowatts)
A 1500 watt microwave should NEVER be on a shared circuit. Assuming
this is a 120 volt circuit, it requires the total capacity of a 15 amp
circuit. Current code REQUIRES a separate dedicated circuit for the
microwave.

In article ,
says...

I have always wondered whether doing all this on one circuit breaker was asking-for-trouble. With all the stereos, TVs, lights etc , that 15 amp CB would ALWAYS blow when i turned the old microwave on when the oven was on. Now it blows even when the oven isn't on.

(The microwave calls itself 1.58 kilowatts)


The microwave should be the only device operating on the breaker. It is
right at the limit of a 15 amp breaker.

What else stops working when the breaker trips ? If anything, I would
say you just have the circuit overloaded and the breaker is doing its
job. If a breaker is reset many times, it can become weak or defective.


One minor point, if you actually have breakers , do not refere to
anything as fuses or fuse boxe. They are breakers and the breaker or
panel box.

You asked how hard it is to change a breker. Not very hard. You cut
off the main breaker, open up the panel box , check with a tester to
make sure the power is off below the main breaker. Unhook usually one
wire from it that goes to the circuit. The breaker will snap out.It may
have a screw holding it in. Reverse the process to get power back on.
There are several companies and types of breakers, so you have to make
sure you get the correct one. Replace it with the same amp rating.
They are there to protect the wiring.

If you have never been in a panel box, do not do it because even though
you cut off the main breaker, there is still some 'hot' wires in the
box.

I think you said there were only 8 breakers. This must be a very small
house/apartment or an older house that was rewired and changed from
fuses to a breaker box.

On Thursday, October 24, 2019 at 10:22:05 AM UTC-4, DManzaluni wrote:
Thanks for this guys but it hadn't struck me that the circuit breaker might be bad. It makes perfect sense. the only other possibility is that whoever wired the breaker box put too much on that circuit, which is something about which we wondered ever since we moved in.

You should know what's on it by now and be able to figure out the
approximate load.




This circuit breaker plainly can't take whatever is on the circuit, - while the probability is that the newer GE Profile microwave uses LESS power than the ancient GE Profile, not more!

How difficult is it to change an individual circuit breaker in an 8 fuse box please?

It's easy, but you have to know what you're doing. With the cover
off there will be live conductors on the service side of the main breaker,
even with it off and those are unfused too.




And can i test whether is (and one other CB which is also blowing far too often) is performing to specs?

Sure. Find every load that's on the breaker. If it's variable, turn
it off. If it's fixed, eg incandescent light bulbs you can turn them on.
Add up the currents, eg a 100W incandescent bulb will be 100/120v = .8 amps.
Take large, known fixed loads, eg hair dryer or small resistance heater
to get close to the breaker limit and beyond. Whatever the dryer is rated,
the actual will be a bit less. Make sure any heating device is set high
enough so that it's full on, constantly. If you're right at the breaker
limit it can take some number of minutes to trip. The further beyond,
the faster it trips.



this is the original CB box that has been in the flat since the building went up about 40 years ago.

6 of the fuses are 20 amp breakers, while the one which blows constantly is a 15 amp one! And although I have a theory that fuse boxes tend to have been installed by competent licensed electricians when the building went Various appliances in the kitchen (but not the fridge or dishwasher or washing machine), including the oven, all wall socket powered lights and 23 pieces of TV/stereo equipment in the living room, all wall socket powered lights, stereo and television in the bedroom etc!!

Unclear what that means. Are you saying all that is on the one breaker?




I have always wondered whether doing all this on one circuit breaker was asking-for-trouble. With all the stereos, TVs, lights etc , that 15 amp CB would ALWAYS blow when i turned the old microwave on when the oven was on. Now it blows even when the oven isn't on.

(The microwave calls itself 1.58 kilowatts)

Don't change the 15a to 20a unless you're sure that the circuit uses
at least 12g wire. You don't say how big this place is, but 8 breakers
isn't much if it's a house. I presume that 15a is for the kitchen
counter? Strange they would put 20a everywhere else, but not there.
Demands have increased, microwave being a key one, but even back then
people had toasters and other small appliances.

This IS a small one bedroom apartment. But now I need to figure out how to put this microwave on either its own breaker or on some minimally utilised one.

Or is it common to add another breaker to the box, if possible without re-wiring the whole place!

On Thursday, October 24, 2019 at 1:14:50 PM UTC-4, DManzaluni wrote:
This IS a small one bedroom apartment. But now I need to figure out how to put this microwave on either its own breaker or on some minimally utilised one.

Or is it common to add another breaker to the box, if possible without re-wiring the whole place!

Adding a breaker is easy, if there is an empty spot for one.
Getting the cable from it to wherever the new receptacle is,
that's another story, which totally depends on what's there,
ie is their access from an attic, basement, etc. Could be
not too bad or real bad. Another option would be to trace
out how the existing problem circuit runs and see if there
is a convenient point you could intercept it and run a new
circuit to and separate it so it's two circuits on two breakers.
But first, I'd make sure it's not just a bad breaker.

On 10/24/2019 1:14 PM, DManzaluni wrote:
This IS a small one bedroom apartment. But now I need to figure out how to put this microwave on either its own breaker or on some minimally utilised one.

Or is it common to add another breaker to the box, if possible without re-wiring the whole place!


I see you tube videos on how to test a circuit breaker and change one.
But, I see you are in an apartment and would imagine apartment
management would be responsible.

Guy at the bank commented that his folks sold their home to move to an
apartment near him. They said they do not even need to change a light
bulb themselves now.

no, this is a coop with strong regulations on who can be uaed to do ANY electrical work, and i think this will be something for a licensed contractor. The coop will demand it if i try to even ask for the main breaker to be turned off pending making any changes to my box

And IMHO that 15 amp cb is a disaster waiting to happen, what with that much stuff on it!

On 10/24/2019 3:06 PM, DManzaluni wrote:
no, this is a coop with strong regulations on who can be uaed to do ANY electrical work, and i think this will be something for a licensed contractor. The coop will demand it if i try to even ask for the main breaker to be turned off pending making any changes to my box

And IMHO that 15 amp cb is a disaster waiting to happen, what with that much stuff on it!


Too bad. I would hire an electrician myself. Years ago when I bought a
generator and had a transfer panel installed they recommended
replacement of my whole home panel because of breakers that were prone
not to trip. An electrician friend confirmed that he knew of the
problem with my panel.

Not sure if you can perhaps save money by following one of the you tube
videos to see if you have a bad breaker before hiring an electrician. I
think all you need is a test meter.

On 10/23/2019 3:52 PM, DManzaluni wrote:
We had a GE microwave that was about twenty years old. Latterly, it started blowing the fuse if i ever ran it with the (gas!) oven on. i figured it had a problem with power consumption.

My neighbor bought all new samsung appliances and said i could take her perfect working GE microwave which is about fifteen years newer than mine was. So i switched my old one for the neighbors newer one.

Now the fuse blows every time i turn the microwave on!!

Besides, of course, only running mine at half power, is there anything I can do to stop the fuse blowing please?


Have you tried it on qa different breaker?

Well i have a test meter but I spoke to the building super and he said that the wiring behind all the CBs is the same. Which makes sense as the one which keeps tripping controls lots of different wall sockets all around the flat.

i wonder how much improvement I would see if I just change the offending CB from 15 amps to a 20 amp CB? i have no real reason to think there is anything wrong with the CB that keeps tripping, again, it ONLY trips when I leave that 1.5Kw microwave on. I have no real reason to think it isnt just doing its job. Properly.

What with what Clare said, i do accept that this microwave needs its own CB but should a 5 amp increase in capacity suffice to prevent overload?

On 10/25/2019 7:38 AM, DManzaluni wrote:
....

i wonder how much improvement I would see if I just change the offending CB from 15 amps to a 20 amp
CB? i have no real reason to think there is anything wrong with the
CB that keeps tripping, again, it ONLY trips when I leave that 1.5Kw
microwave on. I have no real reason to think it isnt just doing its
job. Properly.

What with what Clare said, i do accept that this microwave needs its
own CB but should a 5 amp increase in capacity suffice to prevent overload?


Not tripping the breaker isn't sufficient -- the breaker was almost
certainly sized based on the wiring and the breaker is there to prevent
overloading the wiring itself, NOT the loads on the circuit.

14 ga circuit wiring is NOT adequate for a 20A breaker; it would mean
pulling a 12 ga wire besides just replacing the breaker.

As Clare said, it _should_ have a dedicated circuit by current Code; but
the idea of just putting in a larger breaker is akin to putting a copper
penny in the base of the old fuse box...asking for serious trouble.

It would not hurt to replace the breaker with a new 15A one (or even
swap this one with another 15A one in the box) just to see if by chance
it has become more sensitive with age and consistent tripping. Does
happen...

That said, the real answer is to either distribute the load across more
existing circuits (without running extension cords all over to do so) or
add another circuit or upgrade the existing one--both latter
alternatives mean pulling new wire.

--

On Friday, October 25, 2019 at 9:36:20 AM UTC-4, dpb wrote:
On 10/25/2019 7:38 AM, DManzaluni wrote:
...

i wonder how much improvement I would see if I just change the offending CB from 15 amps to a 20 amp
CB? i have no real reason to think there is anything wrong with the
CB that keeps tripping, again, it ONLY trips when I leave that 1.5Kw
microwave on. I have no real reason to think it isnt just doing its
job. Properly.

What with what Clare said, i do accept that this microwave needs its
own CB but should a 5 amp increase in capacity suffice to prevent overload?


Not tripping the breaker isn't sufficient -- the breaker was almost
certainly sized based on the wiring and the breaker is there to prevent
overloading the wiring itself, NOT the loads on the circuit.

14 ga circuit wiring is NOT adequate for a 20A breaker; it would mean
pulling a 12 ga wire besides just replacing the breaker.

As Clare said, it _should_ have a dedicated circuit by current Code; but
the idea of just putting in a larger breaker is akin to putting a copper
penny in the base of the old fuse box...asking for serious trouble.

It would not hurt to replace the breaker with a new 15A one (or even
swap this one with another 15A one in the box) just to see if by chance
it has become more sensitive with age and consistent tripping. Does
happen...

That said, the real answer is to either distribute the load across more
existing circuits (without running extension cords all over to do so) or
add another circuit or upgrade the existing one--both latter
alternatives mean pulling new wire.

--

Yes, my last posting was designed to take into account your point. Did you not see the bit where I said that the building super said the wiring is the same (gauge) behind all the CBs? I only suggested putting the 20amp cb in place of the 15amp CB BECAUSE the wiring is the same, not because the loads are unknown without a survey!

I can change a CB. I can't distribute the loads more evenly around the whole CB box, and I dont see how anyone could do that without an expensive survey

On Thursday, October 24, 2019 at 3:06:29 PM UTC-4, DManzaluni wrote:
no, this is a coop with strong regulations on who can be uaed to do ANY electrical work, and i think this will be something for a licensed contractor. The coop will demand it if i try to even ask for the main breaker to be turned off pending making any changes to my box

You don't need to turn off anything more than the main breaker in your box
to replace that bad breaker.




And IMHO that 15 amp cb is a disaster waiting to happen, what with that much stuff on it!


While having a circuit that can't support everything that you want to plug
into it is obviously an annoyance, it's not a safety issue, that;s what
the breaker is there for. And the one in question, if anything, appears
to be possibly opening prematurely.

On 10/25/19 8:38 AM, DManzaluni wrote:
Well i have a test meter but I spoke to the building super and he said that the wiring behind all the CBs is the same. Which makes sense as the one which keeps tripping controls lots of different wall sockets all around the flat.

i wonder how much improvement I would see if I just change the offending CB from 15 amps to a 20 amp CB? i have no real reason to think there is anything wrong with the CB that keeps tripping, again, it ONLY trips when I leave that 1.5Kw microwave on. I have no real reason to think it isnt just doing its job. Properly.

What with what Clare said, i do accept that this microwave needs its own CB but should a 5 amp increase in capacity suffice to prevent overload?


If you're going to play electrician, you should have a clampmeter.

But even without a meter, in less than 5 minutes I could shut off the microwave breaker, locate all the dead outlets and calculate an approximate total circuit load.

And if you decide to install a 20 amp breaker on a 14 gauge wire circuit, please take a video of the resultant fire and post to youtube so we can all enjoy.

On Friday, October 25, 2019 at 8:38:16 AM UTC-4, DManzaluni wrote:
Well i have a test meter but I spoke to the building super and he said that the wiring behind all the CBs is the same. Which makes sense as the one which keeps tripping controls lots of different wall sockets all around the flat.

i wonder how much improvement I would see if I just change the offending CB from 15 amps to a 20 amp CB?

As I said previously, you can't change a 15a to 20a unless all the wiring
on that circuit is 12 gauge or better, because the wire can't safely
handle the higher current. It's worth checking what gauge the wire is,
because you say all the other breakers are 20a and this circuit supports
a lot of receptacles. Seems odd they'd use 20a on all the rest, not this
one. It's possible someone replaced it or the electrician only had a
15a that last day, etc.





i have no real reason to think there is anything wrong with the CB that keeps tripping, again, it ONLY trips when I leave that 1.5Kw microwave on. I have no real reason to think it isnt just doing its job. Properly.

If that's all that's on the circuit, it should not trip, the circuit will
support 1800W. If it's tripping, either the microwave pulls more,
which seems unlikely or the breaker is bad.






What with what Clare said, i do accept that this microwave needs its own CB but should a 5 amp increase in capacity suffice to prevent overload?

It's not overloaded now. It's just that the microwave will use most of
the capacity, leaving little for anything else. Sure, it's desirable
to have a receptacle just for the microwave, but most people don't
have that, unless it's a built-in one. Most are using a shared kitchen
counter receptacle. Your solutions that I see, starting from low cost
a

Find out what else is on that circuit. If it's tripping with just the
microwave, high probability the breaker is bad. Verify by putting some
other loads that add up on that receptacle, eg hair dryer, electric
resistance heaters, etc. Replace breaker

Move other loads on that circuit to another circuit, if possible

Get a smaller microwave

Add another circuit, put in new receptacles or split that existing
circuit, etc.

The last one is likely going to get expensive in an apartment,
unless the panel is located somewhere that it's easy to run wire
between it and the new receptacle or where it can be used to
separate the existing circuit, etc. The materials are cheap.
The labor of the electrician and probably opening up walls,
ceilings, repainting, etc is where it gets expensive.

On Friday, October 25, 2019 at 10:25:53 AM UTC-4, DManzaluni wrote:
On Friday, October 25, 2019 at 9:36:20 AM UTC-4, dpb wrote:
On 10/25/2019 7:38 AM, DManzaluni wrote:
...

i wonder how much improvement I would see if I just change the offending CB from 15 amps to a 20 amp
CB? i have no real reason to think there is anything wrong with the
CB that keeps tripping, again, it ONLY trips when I leave that 1.5Kw
microwave on. I have no real reason to think it isnt just doing its
job. Properly.

What with what Clare said, i do accept that this microwave needs its
own CB but should a 5 amp increase in capacity suffice to prevent overload?


Not tripping the breaker isn't sufficient -- the breaker was almost
certainly sized based on the wiring and the breaker is there to prevent
overloading the wiring itself, NOT the loads on the circuit.

14 ga circuit wiring is NOT adequate for a 20A breaker; it would mean
pulling a 12 ga wire besides just replacing the breaker.

As Clare said, it _should_ have a dedicated circuit by current Code; but
the idea of just putting in a larger breaker is akin to putting a copper
penny in the base of the old fuse box...asking for serious trouble.

It would not hurt to replace the breaker with a new 15A one (or even
swap this one with another 15A one in the box) just to see if by chance
it has become more sensitive with age and consistent tripping. Does
happen...

That said, the real answer is to either distribute the load across more
existing circuits (without running extension cords all over to do so) or
add another circuit or upgrade the existing one--both latter
alternatives mean pulling new wire.

--

Yes, my last posting was designed to take into account your point. Did you not see the bit where I said that the building super said the wiring is the same (gauge) behind all the CBs? I only suggested putting the 20amp cb in place of the 15amp CB BECAUSE the wiring is the same, not because the loads are unknown without a survey!

Well, that's a lucky break. But you need to verify it by checking the
wire gauge at the breaker and at all the receptacles on that circuit.
If they are all 12g, then you can replace it with a 20a breaker.




I can change a CB. I can't distribute the loads more evenly around the whole CB box, and I dont see how anyone could do that without an expensive survey

DPB wasn't suggesting fiddling with the wiring in the panel, you can't do
anything there to distribute loads. He was talking about moving any appliances,
lights, etc that are plugged into the problem circuit to another circuit.

On 10/25/2019 9:25 AM, DManzaluni wrote:
On Friday, October 25, 2019 at 9:36:20 AM UTC-4, dpb wrote:
On 10/25/2019 7:38 AM, DManzaluni wrote:
...
....

It would not hurt to replace the breaker with a new 15A one (or even
swap this one with another 15A one in the box) just to see if by chance
it has become more sensitive with age and consistent tripping. Does
happen...

That said, the real answer is to either distribute the load across more
existing circuits (without running extension cords all over to do so) or
add another circuit or upgrade the existing one--both latter
alternatives mean pulling new wire.

--

Yes, my last posting was designed to take into account your point. Did you not see the bit where I
said that the building super said the wiring is the same (gauge)
behind all the CBs? I only suggested putting the 20amp cb in place
of the 15amp CB BECAUSE the wiring is the same, not because the
loads are unknown without a survey!

I saw it yes; but that isn't convincing evidence that's what that
statement means (or is even correct). It would be quite unusual to have
run 12 ga wire for all circuits and then stick a 15A breaker in one
slot--I'd not bet much at all that that is the case--and I'd certainly
not swap out the breaker w/o verifying is so.

It is possible, granted--I'd just put the odds at being so as low.

I can change a CB. I can't distribute the loads more evenly around the whole CB box, and I dont see how anyone could do that without an expensive survey


The point is to plug whatever else is on that circuit into another if at
all possible...has nothing whatever to do with the box itself. Or,
replace any old incandescent lights with LED or similar load-reducing
efforts. Just don't string a bunch of extension cords all over to move
stuff.

--

On Fri, 25 Oct 2019 05:38:10 -0700 (PDT), DManzaluni
wrote:

Well i have a test meter but I spoke to the building super and he said that the wiring behind all the CBs is the same. Which makes sense as the one which keeps tripping controls lots of different wall sockets all around the flat.

i wonder how much improvement I would see if I just change the offending CB from 15 amps to a 20 amp CB? i have no real reason to think there is anything wrong with the CB that keeps tripping, again, it ONLY trips when I leave that 1.5Kw microwave on. I have no real reason to think it isnt just doing its job. Properly.

What with what Clare said, i do accept that this microwave needs its own CB but should a 5 amp increase in capacity suffice to prevent overload?
The wiring is sized for 15 amps. Putting in a 20 amp would allow the
wiring to be overloaded - not a good idea.

I have another suggestion though. With everything else OFF turn on
the microwave, then tuen on everything else. DOes the breaker trip?
Might be high surge current when starting the microwave (or one of the
other devices - like a high power stereo amp) - and a "high magnetic"
breaker MAY solve the problem.
I had a problem with my central vac occaisionally tripping the
breaker. It was on a "dedicated" circuit (I DID plug my Wifi Router
and Cable Modem in to it). I switched the breaker out to a tandem
(120/240) breaker which is a "high magnetic" design and it has not
tripped since. The tandem breaker was a LOT easier to find (and
cheaper)than a single "high magnetic" breaker for my QO loadcenter.

from Schnieder website:

Standard QO115 and QO120 circuit breakers are manufactured to have a
magnetic trip point at approximately 8x to 10x the breaker rating.
There are some applications, however, in which a load has an inrush
current high enough to cause these standard circuit breakers to trip.
Examples of these loads include area lighting for athletic fields,
parking lots, or outdoor signs. To allow the high inrush current
without tripping the circuit breaker, a high magnetic breaker should
be used. These high magnetic breakers breakers have a magnetic trip
point set much higher than the standard circuit breakers. They can be
identified by the HM suffix on the catalog number (QO115HM). Current
production HM breakers are also identified with a "High Magnetic"
label on the side of the breaker (see photo).
NOTE: The above explanation comparing the standard breaker to the
high magnetic breaker applies to 1-pole, 15A and 20A, QO, QOB, QOU,
HOM and CHOM breakers only. Other ampere 1p breakers, and all 2-pole
and 3-pole versions are already high magnetic as standard. (Breakers
with suffix GFI, AFI, CAFI, or DF are not available as high magnetic).

On Fri, 25 Oct 2019 08:36:08 -0500, dpb wrote:

On 10/25/2019 7:38 AM, DManzaluni wrote:
...

i wonder how much improvement I would see if I just change the offending CB from 15 amps to a 20 amp
CB? i have no real reason to think there is anything wrong with the
CB that keeps tripping, again, it ONLY trips when I leave that 1.5Kw
microwave on. I have no real reason to think it isnt just doing its
job. Properly.

What with what Clare said, i do accept that this microwave needs its
own CB but should a 5 amp increase in capacity suffice to prevent overload?


Not tripping the breaker isn't sufficient -- the breaker was almost
certainly sized based on the wiring and the breaker is there to prevent
overloading the wiring itself, NOT the loads on the circuit.

14 ga circuit wiring is NOT adequate for a 20A breaker; it would mean
pulling a 12 ga wire besides just replacing the breaker.

As Clare said, it _should_ have a dedicated circuit by current Code; but
the idea of just putting in a larger breaker is akin to putting a copper
penny in the base of the old fuse box...asking for serious trouble.

It would not hurt to replace the breaker with a new 15A one (or even
swap this one with another 15A one in the box) just to see if by chance
it has become more sensitive with age and consistent tripping. Does
happen...

That said, the real answer is to either distribute the load across more
existing circuits (without running extension cords all over to do so) or
add another circuit or upgrade the existing one--both latter
alternatives mean pulling new wire.


Try replacing with an HM breaker - high magnetic trip. Protects at 15
amps for steady load but allows a MUCH higher surge current. Normal 15
amp breaker will hold about 125 amps of surge. HM will hold over 300.

On Fri, 25 Oct 2019 11:58:11 -0500, dpb wrote:

On 10/25/2019 9:25 AM, DManzaluni wrote:
On Friday, October 25, 2019 at 9:36:20 AM UTC-4, dpb wrote:
On 10/25/2019 7:38 AM, DManzaluni wrote:
...
...

It would not hurt to replace the breaker with a new 15A one (or even
swap this one with another 15A one in the box) just to see if by chance
it has become more sensitive with age and consistent tripping. Does
happen...

That said, the real answer is to either distribute the load across more
existing circuits (without running extension cords all over to do so) or
add another circuit or upgrade the existing one--both latter
alternatives mean pulling new wire.

--

Yes, my last posting was designed to take into account your point. Did you not see the bit where I
said that the building super said the wiring is the same (gauge)
behind all the CBs? I only suggested putting the 20amp cb in place
of the 15amp CB BECAUSE the wiring is the same, not because the
loads are unknown without a survey!

I saw it yes; but that isn't convincing evidence that's what that
statement means (or is even correct). It would be quite unusual to have
run 12 ga wire for all circuits and then stick a 15A breaker in one
slot--I'd not bet much at all that that is the case--and I'd certainly
not swap out the breaker w/o verifying is so.

It is possible, granted--I'd just put the odds at being so as low.

I can change a CB. I can't distribute the loads more evenly around the whole CB box, and I dont see how anyone could do that without an expensive survey


The point is to plug whatever else is on that circuit into another if at
all possible...has nothing whatever to do with the box itself. Or,
replace any old incandescent lights with LED or similar load-reducing
efforts. Just don't string a bunch of extension cords all over to move
stuff.
Where is this flat located? What model load center is installed?
WHat circuit breaker is currently installed??????

Where is this flat located? What model load center is installed?
WHat circuit breaker is currently installed??????

Sorry, not sure of these technical details but I sure feel more comfortable trusting your statement that it is unusual to put a 15 amp cb on wiring sized for 20 amps, rather than my super's supposition that 'all wiring behind the box is the same'!

By the way, I should mention that when the cb trips, it does so after a minute or so of the microwave being turned on. It doesnt happen immediately.

On 10/24/2019 8:23 AM, Ralph Mowery wrote:
In article ,
says...

I have always wondered whether doing all this on one circuit breaker was asking-for-trouble. With all the stereos, TVs, lights etc , that 15 amp CB would ALWAYS blow when i turned the old microwave on when the oven was on. Now it blows even when the oven isn't on.

(The microwave calls itself 1.58 kilowatts)


The microwave should be the only device operating on the breaker. It is
right at the limit of a 15 amp breaker.

What else stops working when the breaker trips ? If anything, I would
say you just have the circuit overloaded and the breaker is doing its
job. If a breaker is reset many times, it can become weak or defective.


One minor point, if you actually have breakers , do not refere to
anything as fuses or fuse boxe. They are breakers and the breaker or
panel box.

You asked how hard it is to change a breker. Not very hard. You cut
off the main breaker, open up the panel box , check with a tester to
make sure the power is off below the main breaker. Unhook usually one
wire from it that goes to the circuit. The breaker will snap out.It may
have a screw holding it in. Reverse the process to get power back on.
There are several companies and types of breakers, so you have to make
sure you get the correct one. Replace it with the same amp rating.
They are there to protect the wiring.

If you have never been in a panel box, do not do it because even though
you cut off the main breaker, there is still some 'hot' wires in the
box.

I think you said there were only 8 breakers. This must be a very small
house/apartment or an older house that was rewired and changed from
fuses to a breaker box.


If this is an apartment, ask the landlord to fix the breaker.

On 10/25/2019 4:15 PM, DManzaluni wrote:

Where is this flat located? What model load center is installed?
WHat circuit breaker is currently installed??????

Sorry, not sure of these technical details but I sure feel more
comfortable trusting your statement that it is unusual to put a 15
amp cb on wiring sized for 20 amps, rather than my super's
supposition that 'all wiring behind the box is the same'!
It's certainly far more conservative and known to be in Code as 14 ga is
smallest for general circuits. If you have access to the box, it's
simple enough to find out...in a condo w/ owner association, though,
it's quite likely that's a "not allowed" operation by the householder.

You can, of course, pull the cover off the outlet and see what runs to
the outlet. It would be unusual for it to be different from one end to
another, but not impossible and the breaker has to be sized for the
smallest wire size on the circuit.

By the way, I should mention that when the cb trips, it does so after
a minute or so of the microwave being turned on. It doesnt happen immediately.

That's indicating the steady load is too much or the previous
possibility mentioned that the breaker is thermally sensitive.

Is there anything else on that circuit at the time?

The A/C compressor breaker here developed such a symptom a few years
ago...it's not impossible that a new 15A replacement won't trip.

--

On Fri, 25 Oct 2019 14:15:01 -0700 (PDT), DManzaluni
wrote:


Where is this flat located? What model load center is installed?
WHat circuit breaker is currently installed??????

Sorry, not sure of these technical details but I sure feel more comfortable trusting your statement that it is unusual to put a 15 amp cb on wiring sized for 20 amps, rather than my super's supposition that 'all wiring behind the box is the same'!

By the way, I should mention that when the cb trips, it does so after a minute or so of the microwave being turned on. It doesnt happen immediately.
Then we KNOW it is overload, not surge. What goes out with the
microwave when the breaker trips? List EVERYTHING on the circuit - and
with it ALL turned off/unplugged does it still trip?

Yes, I am pretty sure now that it is overload and that some way will have to be found of getting a line from the microwave to a spare slot for a new cb.

When the microwave isn't on, the breaker never trips; and with the old GE Profile, I could prevent tripping by turning down to half power.

Curious that the super didn't seem to know that (I'm sure that) everyone in the building needs to install a separate breaker whenever anyone puts a modern microwave in but I'll bet this says more about his competence than it does abut the wiring!

On Sunday, October 27, 2019 at 12:10:50 PM UTC-4, DManzaluni wrote:
Yes, I am pretty sure now that it is overload and that some way will have to be found of getting a line from the microwave to a spare slot for a new cb.

When the microwave isn't on, the breaker never trips; and with the old GE Profile, I could prevent tripping by turning down to half power.

Curious that the super didn't seem to know that (I'm sure that) everyone in the building needs to install a separate breaker whenever anyone puts a modern microwave in but I'll bet this says more about his competence than it does abut the wiring!

There are certainly plenty of microwaves that can be run on
15A circuits, even with some other small loads. I'd get a new
$100 oven instead of paying $2000 to run a new circuit.
You say that all the other circuits are 20A, is there a 20A
receptacle nearby that you can use with a reasonable extension cord?
I assume you've verified that this circuit still trips with just
the microwave? What is the rating on this MW? Have you tried
running it at 80% power? What happens then? You asked how to check
the breaker and I suggested putting some known resistance loads
on the circuit, increasing towards 15a and see when it trips.