I have an 80 amp breaker for our heater. It keeps overheating and tripping. We think we are supposed to have a 90 amp breaker instead, but can't fine one anywhere. Is it dangerous to use a 100 amp breaker instead of the 90?

Well, considering we know nothing about this "heater", such as what it draws in watts or amps, and what size and type of wire is feeding it, this question is completely unanswerable.

Can you provide us with more details? :confused:

How long did the 80 amp breaker work for you?

The heater should have a nameplate with the voltage and amperage requirements. Using that as a guide, you can put an ammeter on the circuit and see for yourself if the heater is working as specified. Then, if the heater is working properly, and the wiring is appropriate and you are using the correct breaker, we can take you a bit farther into trouble shooting. Weak breaker, loose wiring or a heater that is starting to fail; it could be any of those things. The more information you supply, to more we can assist you. But you should never just put in a larger circuit breaker than either the appliance calls for, or the circuit is designed for.

The 80 amp breaker lasts about 15 minutes then it trips. It is a Goodman heat and air unit. The breaker heats gets really hot right before it trips. I checked the unit inside the house in the attic, and it had two circuits. One circuit called for 60 Amps and the other called for 30 Amps. That is why we were thinking it needed a 90 Amp breaker instead of the 80. We weren't given a instruction manual on the unit, it doesn't have the ampage requirements on the unit, and I can't find them on the internet.

Can you tell us what the wiring is that feeds the unit?? :confused:

The house is five years old and we just bought it 6 months ago. So, the breaker has been in the house at least that long.

If 80 amps worked for 5 years you should not install anything other than 80 amps. Either your breaker is failing or your heaters are drawing more than they should. Do you have the test equipment and knowledge to diagnois this problem or do you feel like you need an on site pro?

Okay,

Where did you check for he electrical specs. Plate? On the unit inside the home or the outside unit?

Are there any tags or labels stuck on the unit giving the installers name and address information?

If your breaker is getting as hot as you say, (I don't doubt you for a minute!) then you need to get an HVAC tech out to your place pronto before the breaker allows a fire to start because of the heat generated.

It is entirely possible that the breaker is under strength or that the feeder conductors to the unit are not sufficient. There appears to be a serious short that is allowing a sustained high current flow before the breaker reacts.

Also, FYI, Amperage is not necessarily cumulative. You do not add them to get the required amperage.

One other thought, contact the builder of this home and see what records he has, but first get some professional help before you burn the home down.

Based on me reading this thread.

This is my speculation sine we don't know the wire size feeding the unit.

I think that what you have is a electric air handler/heat pump (possible) unit, with a 10 KW main element (on the 60 amp) and a 5KW element on the 30 AMP. On every unit I have seen, including my own professionally installed unit, there are two double pole breakers in the main breaker panel, one 60 AMP and one 30 AMP.

You say you have only lived there 6 months.

Is the breaker panel full? Because it almost seems like someone decided to make room in the breaker panel by removing the 30 AMP 5KW breaker and just tieing it into the 60. But lo, that caused the breaker to trip, so the old homeowner decided to put in an 80 AMP breaker, as the capacity of an 80 amp breaker, would be about 64 amps, and at 240 volts, 15 kw should come righ under that, but it's close.

The solution could be simple? You need to see what kind of wire feeds the unit. Is there a #6, OR #8 wire as well as a #10 wire? If this is the case, then you need to go to the breaker box and split the two circuits again. Put the large wire (#6 or #8) on the 60 AMP breaker, and the small wire (#10) on a 30 AMP breaker.

But the answer lies in what the gauge of wire(s) that run to the unit. That is a vital piece of information that this question can not be answered without.

In the mean time, while you are sorting this problem out, go to the heater and turn off the 30 AMP breaker. This should kill the 5KW element and stop the breaker from tripping. The furnace should continue to run as the control circuit should be wired through the 10KW system. (60 AMP breaker). Your heat just won't be as hot, but it's safer than letting it run the way it is. Then you might be better off to have a heating and cooling contractor come in and evaluate the system.

EDIT: The gauge wire should be printed on the side of the wire itself.