troubleshooting electrical circuits?

Question

this is an air contitioning circuit.the breaker trips off every 45 minutes,i've tested voltage(236 v) current,(15 amps on each hot leg)
,the plate on the unit calls for a 40 amp breaker and that's what it actually has.Conductors:6 awg.Everything seems normal but it still trips off the breaker.What else should i look for?

the breaker is brand new,if its a hvac breaker i don't know.Does it have a label that says?.What i know is that it has a single lever unlike most of double pole breakers that have two linked.The ac unit is new as well.

Answer 1

Is the breaker good? If for some reason it's tripping when it gets warm than that will cause your problem. Also, what are the running amps of the condensor motor? Is the motor drawing large amounts of amps when it gets warm? What is the starting amps of the motor? Somewhere there should be tag telling you what the starting amps and running amps of the motor should be. If they are outside the manufacturers specs then the motor will have to be replaced.

EDIT: never ever install a breaker larger than the manufactures instructs. Unless you don't mind burning down your house.

Answer 2

The breaker may have a thermal disconnect in it, meaning if the breaker heats up to a certain point, the breaker will trip to prevent a fire hazard. An air conditioner draws a lot of current, and if it is used for long periods of time, the wires will heat up.

You mentioned 15 amps of current on each hot leg. Is this the amount of current per leg that the A/C is drawing when it's on, or is this the amount measured with the a/c off? It may be drawing close to the 40 amp limit during operation. Check the a/c specs, and if need be, have an electrician look at it.

You might want to have an electriclian check it anyway, as I have been living in my house for over 11 years, and just found out that the wall sockets downstairs and in the garage were all wired backwards, and some were missing ground connections.

If the a/c is causing the breaker to heat up, definitely get that checked on, as if the thermal connector fails, it might start a fire.

Answer 3

the connection at both the AC and the breaker are tight ( as in proper torque applied at the AC terminals and the breaker screws as well, also the breaker is snug on the bus bar in the panel? ) as a loose fitting breaker or loose terminal screws will heat up the wire and thus trip the breaker
and they do make 2 pole breakers with a single trip level, typicaly they body is 2 inches wide ( since it will use 2 1 inch slots or 1 1/2 if is uses 2 3/4inch slots )
you did not mention your panel ( GE, Sqaure D, Zinsco, Federal Pacific ) and the make of the breaker used, HVAC breakers have a delay for trip as they allow for inrush current that a AC can draw, this temporary spike in amps will trip normal breaker with normal delay times, some AC will have capcitors to offeset the inrush current

Answer 4

Just wanted to comment on an earlier answer, the plate says a 40 amp breaker, do not under any conditions go higher than that. the breaker is the safe guard for the whole system, it is supposed to be the weakest link. If you just replace it with a higher amp breaker you run a high risk of a fire.

Answer 5

Is the breaker an HVAC breaker? This is needed for the high in rush current of AC commpressor starup. You cannot measure this in rush with normal amp meters. The in rush would be much higher than the 40 amps initialy. If you do have an HVAC breaker it could be going bad or the compressor or compressor capacitor could be going bad in the unit. Both of these second and third items could be checked with special meters.

Answer 6

When you flip a switch in your home and nothing happens, you have to start thinking about what could be wrong. Testing the switch is an option, but should be done after checking the most obvious possible problems first. Those might be a burned out bulb, a tripped circuit breaker, or even a fuse that may have blown. But when one of these isn’t the solution, then it is very likely that the trouble stems in the switch itself or the wiring associated with the switch. To narrow down your search and identify that the switch is the culprit, you can perform an out-of-the-circuit test or an in-circuit test to examine the switch.

Answer 7

Replacing the breaker(s) with a new one of the appropriate amperage is a good start. Make sure your air conditioner is in proper working order. Some motors will trip breakers as they overload. If the fins on the air conditioner are plugged it will cause the unit to be overworked (and therefore possibly overloaded).

Answer 8

if this breaker is for the outside unit this would indicate there is somekind of compressor problem....need more information to tell you anymore...everything else seems ok...no condenser fan motor would pull enough power to knock a forty amp breaker unless it burnt up and quit running

Answer 9

A/C compressor is pulling too many amps or length of the wire run is too long and decreasing the amps available. Consult a wire run chart to see if you need to go with thicker wire for the length of the run and amps required.
http://www.powerstream.com/Wire_Size.htm
Only things I can think of.

Answer 10

how old are the breakers,? they will get weaker with age, if they trip a lot go to a 45 amp breaker, or 50 amp, with all the heat we have had it may be causing it,