Hi folks,

I bought a used, old coffee machine. the power specification is 110v, 60hz, single phase.

I live in the us. When I plug it, it will work for some time, then the breaker trips. I could not find a technician willing to check it--I live in a small town. I took it to a car electrician, and he told me that there was a short circuit, and he fixed it. I took it back home, and the problem occurred again. Took it to his shop, and we plugged it, and it worked fine for maybe 15 min. So, I thought maybe the kitchen socket does not withstand the supply needed for this machine--I am not sure, but I think it is 1200 watts. I operated it on the AC socket and it worked for maybe 30 min, and the problem occurred again. (the ac plug says 120v, 1800 watts)

Do you think the 110v and high watts required is causing the problem? I think if there is a short circuit, then it would not operate at all?

Any advise or help!

Thanks.

 

Welcome to AAC!

1800W would draw 15 amps. Do you have anything else on the circuit when the breaker trips? Do you have any 20 amp circuits you can try?

I only have 1 20 amp circuit in my kitchen (for general purpose receptacles). The only reason I have that is one circuit was tripping and the electrician said the wire gauge would handle 20 amps and swapped the breaker.

My coffee maker is 900W, but it's on the same circuit as my toaster oven...

 

Hi Dennis,

Yes, the AC plug says 15 AMP.

When I connect the maker--it is actually espresso maker with 1.2 L brass boiler--just a neon light and a wireless router. I am not sure about 20 AMP. Should I check the breaker to know if I have 20 amps? If yes, then I would not be able to do it till the morning.

Thanks

 

If there is a short in the heating coil, it would lower the resistance and increase the wattage. My guess is that your breakers need to be replaced. A breaker is good for only 6-8 trips before it needs to be replaced. If the breaker is bad, it will keep tripping at lower and lower powers (amps). Try the coffee pot on another circuit.

 

I think in this case I need to call the maintenance to check the breakers and show me if there is a 20 amp circuit or not.

Thanks.

 

Agree with dl 1800/120 is 15 A and a 15 A breaker will likely die after some time. It's on the hairy edge. Although it probably doesn't draw 15 A for very long, the fridge turning on if it'son the same circuit could cause a trip. 20 A circuits are probably scare. The bath and kitchen are locations where 20 A circuits are suggested in newer homes.

 

Just had a similar instance with my sons central heat, after 15mins the breaker would trip, after spending some time checking the unit and finding nothing, it came down to the 30amp breaker, replaced it and works fine.
Max.

 

On older homes, you will often find loose screws on the wiring of 110 outlets. If it will be high current use like window AC or coffee maker just get a new, quality outlet and install. Contacts get oxidized and the brass blades stop holding the plugs and they sag or fall out.

These things last a long time but they DO wear out

 

Thanks all. The home is old; but re-innovated recently. In kitchen, they installed outlets with built-in breaker (I do not know what they call them formally!). So, in kitchen, the breaker breaks sooner than the AC socket, so I suppose it handles less load.

I checked the breakers' box, and saw 10kA, 15KA, 20KA breakers. I am not sure what amps they are--I suppose AMPS values are different from KA values. The AC socket is hooked to 15 KA--it was the tripped breaker.

Now I have better understanding of what I need to tell the maintenance! I will keep you posted!

Thanks.

 

Thanks all. The home is old; but re-innovated recently. In kitchen, they installed outlets with built-in breaker (I do not know what they call them formally!). So, in kitchen, the breaker breaks sooner than the AC socket, so I suppose it handles less load.
.

GFI or ground fault interrupter.
AKA earth leakage trip.
Could be a small leakage on the appliance.
Max.

 

A breaker is good for only 6-8 trips before it needs to be replaced.

Where do you get this information? I have never heard this and it does not sound correct to me. I googled it and found this:

Questions have been raised in the
industry regarding the integrity of a
circuit breaker after interrupting a fault.
These questions are typically generated
by fuse manufacturers; NOT the result of
documented problems with breakers in
the field. The fuse manufacturers
suggest that interrupting a fault shortens
the useful life of a circuit breaker,
bringing in questions about the ability of
a circuit breaker to continue to perform
its protective function. They imply that
adequate testing of the circuit breaker
can not be performed in the field and
therefore its integrity can not be verified.
In this way, they claim, a circuit breaker
is no different than a fuse and should be
replaced after clearing a fault.

Molded case circuit breakers are
designed and tested to be capable of
safely clearing many overcurrents
during their normal span of operation.
Since their introduction in 1928, breakers
have proven this capability through
decades of safe, reliable performance.
The number of overcurrents a specific
breaker can clear depends greatly on the
magnitude of the overcurrents
interrupted. The Underwriter’s
Laboratories test standard for molded
case circuit breakers, UL489, requires
that a breaker must safely clear its
maximum current, which is the short
circuit current rating of the breaker, twice
and still be functional. In addition, the
UL489 test requires that a breaker,
depending on the frame size, must
operate up to 50 times under a 600%
overcurrent and up to 6000 times under
rated continuous current.

 

I'm with strantor. 40 years of doing house calls and I have found (1) one breaker that would not hold properly.
The problems are usually about loose connections that got too hot or the fins in the back of the breaker box that got corroded, but the breaker is still good if it didn't get melted.

ps, new wall outlets cost about 50 cents here.

 

Sounds as if the OP has GFI sockets?
And with an old, used appliance, it could be earth leakage.
Max.

 

So, I thought maybe the kitchen socket does not withstand the supply needed for this machine--I am not sure, but I think it is 1200 watts.

Does the kitchen outlet have GFCI? I have seen coffee makers with crud buildup trip Ground Fault type circuit breakers if the crud has a low current path to ground. Just something else to consider. Our coffee machine at work would get dirty and wet inside and trip the GFCI breakers. Take it apart, clean it thoroughly and we were good for another month. You can also try in on another circuit using a different breaker.

I vote with Max.

Ron

 

A breaker is good for only 6-8 trips before it needs to be replaced.

Are you sure about that or am I just lucky? I have used my 30A breakers for my air compressor as a "switch" for over 20 years now. Wouldn't that be just like a breaker "tripping"?

 

Are you sure about that or am I just lucky? I have used my 30A breakers for my air compressor as a "switch" for over 20 years now. Wouldn't that be just like a breaker "tripping"?

Switching is NOT like over current trips, let alone short-circuit trips. Switching duty breakers used to be a specific type of breaker, and I doubt that an older, residential use, economy grade breaker will withstand very many trips without substantially affecting the trip curve. Newer wiring may give the OP or others like him a bit better trip characteristic, but the newer wiring practices are lousy, and I trust none that I haven't done or closely inspected myself.

If the OP has #12 wiring, good quality ("commercial grade") wiring devices with no "push-wire" terminations or splicing, and neither GFI, GFCI, or "arc-fault interruptor" devices, and a 20A branch circuit breaker, his machine should function just fine. This is the type of circuit that the machine he describes was intended to be supplied by.

 

I doubt that an older, residential use, economy grade breaker will withstand very many trips without substantially affecting the trip curve.

Why? I can see low quality contacts failing more rapidly than high quality ones, but a magnetic breaker that has "normal" levels of AC through it continuously or often isn't going to change inductance just because of a few excursions above its trip point. Is it?

ak

 

I checked the breakers' box, and saw 10kA, 15KA, 20KA breakers. I am not sure what amps they are--I suppose AMPS values are different from KA values. The AC socket is hooked to 15 KA--it was the tripped breaker.

kA is killo-amps. It's basically saying that during a lightning strike a 20 kA breaker is better than one rated for 10 kA. In other words, a breaker rated at 10 kA can interrupt safely 10,000 Amps.

Breaker ratings are usually on the handle of the breaker. 14 AWG is usually 15A and 12 AWG is usually a 20 A circuit.

 

Why? I can see low quality contacts failing more rapidly than high quality ones, but a magnetic breaker that has "normal" levels of AC through it continuously or often isn't going to change inductance just because of a few excursions above its trip point. Is it?

ak

We're dealing with mass produced mechanical devices that sell for less than $10 each, and are thermal-magnetic. They have springs, rockers, and other simple elements. The springs and bimetallic thermal trip mechanisms are what get out of "calibration" quickest, but other things happen as well.

 

There's plenty of information out there about how thermal-magnetic circuit breakers work, are to be selected, are rated, are tested, etc. Probably a good bit of it on he web. But this isn't it, or intended to be. I detect things here on the thread being not well stated or understood. Breakers have voltage, interrupt, environmental, thermal, magnetic, temperature, ambient, tolerance, curve, load carrying and auxiliary contact ratings and characteristics, amongst others. They are often installed in residential settings out of conformity with the manufacturers specifications, and the resultant actions are affected. I used to prefer to carry a certain brand of circuit breaker in my service truck because it fit the largest number of different manufacturers panel boards. Some guys used to say they never found a Westinghouse breaker that would trip on anything less than a short circuit.

Now, a circuit breaker is entirely different than a receptacle or other local, box-mounted device with a GFI, GFCI, or arc-fault interruptor. Entirely different. This thread has become a discussion of some very limited aspects of small single pole circuit breakers, but the actual load current characteristics of the OPs load device are still very unclear.

It may have a contact, element or connection that occasionally produces an arc. It may have an intermittent "partial short" or open or high impedance point.

I think that having a fairly simple, clean 20A supply circuit will make troubleshooting a lot easier for the OP. Of course recording ammeters, and other expensive test equipment might help too, but I think he can find the problem without it.