Which Cutler-Hammer breaker to use ?

jCarroll

Well-known Member
Location
mid-Ohio
Bought a new window air conditioner for an upstairs bedroom.
Run off a 14ga branch circuit with no other load.
AC trips the BR115 breaker about once a week.
I swapped breakers to eliminate the " weak breaker" issue - no difference.

AC pulls 10 amps running, pegs my 30 amp meter for a second when the compressor starts.

Service says it will take BR, BRH,BRAF, and QFCB breakers.
Which would handle the staring load best?

Thx in advance.
 

The AC supply circuit should be a separate dedicated supply. This circuit being shared complicates the issue and limits the breaker per electrical code to 15amp.
A dedicated 20amp T-Slot receptacle , 12 gauge wire and a 20amp breaker is the solution . Actually a central AC unit would be ideal. That is also the next large project for Mrs. B&D.
 
I don't air condition and don't know too much about doing it but I have a question. Why do you
recomend central air? I would think 2 or 3 window units would be cheaper and if at any time they
need service you can take it to the service. Should be less money than having the service come out
to you. And if one is out the others would still be working. Just wondering, is it less money torun
central?
 
Sounds more like you may have a defective window unit.

But before taking it back, look the bus bars in the breaker panel over. If the bar is corroded or shows evidence of overheating, the heat will transfer to the breaker causing it to false trip. If it is damaged, and have room, relocate the breaker to a better slot that has not been burned. Also be sure the wire connections are tight at the receptacle and on the neutral bar. And any other connections feeding the panel, main breaker, etc.

When does it trip? On start up or while it's running? If on start up, likely the AC unit. If while running, and it consistently runs at 10 amps, an electrical problem.
 
At one time that would call for an HACR breaker which meant heating air conditioning refrigeration. Somewhere recently I may have read that designation of breaker may not be used anymore. I don't know if it is still a requirement. Usually a new window unit calls for a new dedicated circuit of 12awg not 14 gauge.
 
It can be efficient ; if you have three rooms but only use the window unit in the one room you sleep you will beat the central air cost. The trouble with window units is often the electrical work to install new outlets under each window. The cost of outlets to feed them.
 
Part of the problem may well be the 14 gauge wire and if it has a long run your likely to be loosing some power which will cause that. Me I would NEVER have any 14 gauge wire in a house but I did tend two over wire and if code calls for 14 gauge I use 12 and if 12 if called for I use 10
 
Many years ago when I worked midnight shift and slept in the day time I had the same problem. I finally ran a 12ga circuit and 20 amp breaker. I still remember having to go in my hot attic and fishing the new cable inside of the wall. It was worth it to finally get some sleep on those hot days.
 
Looks like it may NOT be a breaker problem, but perhaps voltage drop across 14 Gauge wire and long sustained currents (AC and maybe?? other loads) too close to the breakers rating. Are there any OTHER loads on that branch circuit in addition to the AC ???????????????? With even a good circuit breaker a long sustained current draw (say approximately 12 to 14 range) can eventually trip a thermal magnetic circuit breaker on its thermal. If you want to go to the time and expense Id guess a 12 gauge 20 amp branch circuit with a 20 amp receptacle especially if dedicated to the AC ONLY will cure the problem. Sure, breakers can deteriorate to some degree and a new one might??? fix it, that's sure easier and cheaper even if NOT the absolute best method.

John T
 

Per ton of capacity the central units use less power and make less noise . Centrals last longer and don't pose as high of the home security issue . The central stays in place while the window shakers are removed for fall, winter and spring.
 
Once I worked for a contractor who did work for a large appliance store. He was supposed to run lines for window units all over the house. Back then dedicated lines were about 250 bucks a run. so it was about a 2000 dollar job. When he gets to the house he says to the home owner why don't you just get central air ? Guy says okay good idea . Appliance store loses sales of 8 units and was not happy. Needless to say they never called my boss for work again after that.
 
No other load on circuit.
AC is maybe 60' of ,wire back to the service panel.

How is an BRH breaker different from BR ?
 
From the manufacturers data, the difference between the BR and BRH is the interrupting current rating. The BR is 10,000 amps and BRH is 20,000 amps. Also the state that all BR breakers are HACR rated.

Your issue is most likely due to the wire size and length of wire. When the compressor motor starts it requires a larger inrush of current which can be up to 7 times the running current. With that high current draw you get a large voltage drop which means the motor will take longer to come up to speed and to the running current. With larger wire size you get less voltage drop, the motor starts quicker and the breaker does not see as high of a thermal load.

Using your 30amp inrush measurement with 60' of 14 gauge wire you have almost an 8% drop in voltage at the motor. They recommend no more than 5% which is what a 12 gauge wire will give you.
 
60 feet is way to long a wire to work well when a 14 gauge is maxed out at 15amps and line loss is way to high that distance
 
Too much "starting" juice during momentary power losses.

I would recommend.....20 amp breaker on a #12 supply wire.

John,PA Refrig.engineer.
 
I'm thinking that's just what the doctor ordered. That 14 gauge is the hangup, and naturally 12 gauge goes with a 20 amp breaker. I bet that wire probably even gets pretty warm if someone could get back behind the recept to touch it. I had a 110 air compressor that got so hot that it would just shutdown to cool off. The problem was 14 gauge wire and 15 amp breaker to the recept not enough to carry the current. Brought it up to snuff, never a problem again.

Mark
 

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