Circuit breaker constantly trips


  #1  
Old 07-21-04, 06:35 PM
Bsalh's Avatar
Member
Thread Starter
Join Date: Jan 2004
Location: Ottawa, Ontario
Posts: 14
Upvotes: 0
Received 0 Upvotes on 0 Posts
Circuit breaker constantly trips

I just got my central A/C unit moved to another location beside the garage. Since then we've had 2 instances of the electricity going out for a couple of seconds then coming back on. On both instances the breaker for the A/C tripped. No other breakers tripped. This has never happened before moving it. Is it possible that the installers didn't wire it properly or is there something else.

Thanks in advance.

B
 
  #2  
Old 07-21-04, 06:55 PM
CSelectric
Visiting Guest
Posts: n/a
Let me see if I understand this fully. When the A/C kicks on, there is a large voltage drop (lights dimming, electronic equipment, TVs and such potentially shutting off) then the A/C breaker trips?

If that is correct, then my first question is - how far did you move the A/C unit? This sounds a bit like a voltage drop problem, caused by excessive distance or undesized cable, but I don't yet know enough to diagnose it accurately.
 
  #3  
Old 07-21-04, 06:57 PM
J
Member
Join Date: Sep 2000
Location: United States
Posts: 17,733
Upvotes: 0
Received 1 Upvote on 1 Post
Exactly what loses power for two seconds? The air conditioner? Everything else? Everything including the air conditioner? Is it really two seconds (which is a pretty long time)? Does it go completely out, or do lights just dim?

When power comes back, does it come back to the air conditioner too? Everything but the air conditioner?

Is the breaker that trips a GFCI breaker?

Has the A/C been running for hours before the breaker trips?
 
  #4  
Old 07-21-04, 08:11 PM
GregH's Avatar
Super Moderator
Join Date: Jan 2001
Location: Manitoba
Posts: 9,500
Received 68 Upvotes on 62 Posts
Bsalh,

It is possible that something went wrong when the airconditioner was moved.
Air in the system or a refrigerant overcharge could cause the compressor to be overloaded causing it to throw the breaker.

Or, you are having a momentary power failure that causes the compressor to stop and then attempt to restart without enought time for the pressures to equalize.
The compressor must remain off for at least three minutes to be able to restart.

If power outages are frequent where you are, there is a solid state time delay available that is relatively inexpensive and will allow a preset off time each time the unit stops.
 
  #5  
Old 07-22-04, 04:52 PM
Bsalh's Avatar
Member
Thread Starter
Join Date: Jan 2004
Location: Ottawa, Ontario
Posts: 14
Upvotes: 0
Received 0 Upvotes on 0 Posts
Sorry folks. I guess I didn't explain fully. I meant a very short power failure (a few seconds). You know the one where everything is on off on, like flicking a light switch with a 2 second interval or so. The unit is running and when this happens the circuit breaker goes. All other breakers are fine and only the A/C one goes. However, I think Gregh got it. I didn't know that if the power is off for less that 2-3 minutes the breaker would go? And why is that? Wouldn't it just simply stay off until it reached the required interval then restart?

Thanks in advance.

B
 
  #6  
Old 07-22-04, 05:10 PM
J
Member
Join Date: Sep 2000
Location: United States
Posts: 17,733
Upvotes: 0
Received 1 Upvote on 1 Post
Breakers don't reset themselves. If the breaker trips, the A/C won't start again until you go out and manually turn the breaker back on. Is that what is happening?
 
  #7  
Old 07-22-04, 06:16 PM
G
Member
Join Date: Oct 2002
Location: Hamilton County, Ohio
Posts: 3,927
Upvotes: 0
Received 2 Upvotes on 2 Posts
I am not an A/C tech but I seem to recall hearing that sometimes, when the A/C is shut down, then turned back on in a matter of seconds, the A/C compresser motor cannot overcome the head pressure and trips the breaker.
Under normal operation the head pressure bleeds off before the next call for air and the compressor motor can spool up normally.

Do you know why you are having the short outages? Cure that and you should cure the breaker problem.
 
  #8  
Old 07-22-04, 07:15 PM
GregH's Avatar
Super Moderator
Join Date: Jan 2001
Location: Manitoba
Posts: 9,500
Received 68 Upvotes on 62 Posts
Bsalh,

There is a very good reason why some folks have problems with breakers tripping when residential airconditioners are turned off and on quickly.

When selecting a breaker for a central airconditioner there is usually some leeway in which size to use.
If a breaker is selected that is close to the lowest amperage rating that is allowed for the unit, when a high amperage condition exists, as in being unable to restart due to unbalanced pressures the breaker will trip.

If the largest breaker is selected then the compressor will draw locked rotor amperage but before the breaker can trip the compressor windings will overheat and trip the internal winding protector. This condition people will never notice.

I always size the breaker on the small size so that people become aware of the fact that the airconditioner has a problem.

We have extremely reliable power here and the biggest reason breaker tripping on a/c's occur here, is due to people fiddling with the thermostat.

You would be a good candidate for a solid state time delay relay.

An HVAC person should know about these and wouldn't be very costly to have installed.
 

Last edited by GregH; 07-22-04 at 07:26 PM.
  #9  
Old 07-23-04, 11:45 AM
G
Member
Join Date: Oct 2002
Location: Hamilton County, Ohio
Posts: 3,927
Upvotes: 0
Received 2 Upvotes on 2 Posts
The electric was fine - moved A/C - electric not fine.
Who moved the unit and how did they do it? They would have turned off the breaker and maybe the main breaker as well. Did they do anything else in the breaker box ie. run a new cable? If this was a professional job, I would call them back to go over their work. You indicate that you are losing power to the whole house, not just the A/C. You could ask your neighbors if they noticed any recent power " blips". If not, I would have someone check from pole to breaker box for a faulty connection.
 
  #10  
Old 07-24-04, 02:17 PM
Bsalh's Avatar
Member
Thread Starter
Join Date: Jan 2004
Location: Ottawa, Ontario
Posts: 14
Upvotes: 0
Received 0 Upvotes on 0 Posts
John Nelson: Yes that is what is happening. I have to turn the breaker back on manually, of course, and the unit starts up, again.

goldstar/GregH: No I don't know why we were have these local blip-outages and yes I check with the neigbours to ensure that it wasn't only my house. The unit was moved and the breaker was not changed therefore, I assume, the size of the breaker had nothing to do with it since all was well prior. They did run new wire since it's new location was further away than the previous location (about 50' of A/C lines). It's a "Carrier (38CKC)" 3.5 tonne and they checked with the company to ensure the lines were within spec re freon capacity and unit capability because of the distance from the main feed.

It hasn't happened since but nor has a blip outage. If the unit needs a "solid state time delay relay" as GregH suggests, how is it that it needs it now and didn't need it before? Did the increased distance from the main feed case the unit other problems?

Any way, I think I'll contact the company and get them to check it out or give me an explaination. In any case, I'll let this forum know what the story is as soon as it's resolved.

Thanks for the help.

B
 
 

Thread Tools
Search this Thread
 
Ask a Question
Question Title:
Description:
Your question will be posted in: