House A/C problem due to breaker

[kenmac]

Just an FYI ....These are Run capacitors. Not start capacitors

 

[grsthegreat]

Test the start cap as tinhack said it is [possibly] bad but normally once they fail they are dead. My guess is the POS aluminum wire loosened up and caused a voltage drop requiring more amps to start the unit. I don't care what anyone says aluminum wire sucks! I personally have seen it burn down 2 homes so far. This is why they quite using it for branch circuits. Dicharge cap before testing it!!! If you have aluminum wire anywhere check the tightness of it every few years and more often where vibration is present. EG air conditioner. Or replace it with copper if that is a option. CJ

They have NOT discontinued making aluminum wire for branch circuits. They only discontinued it for 15-20 amp circuits. You can still use it on larger branch circuits. Todays alum wires are nothing like those of old.

we use it all the time. Also, all the power lines overhead are aluminum. It works great as long as its installed properly.

 

[rbstern]

They have NOT discontinued making aluminum wire for branch circuits. They only discontinued it for 15-30 anp circuits. You can still use it on larger branch circuits. Todays alum wires are nothing like those of old.

we use it all the time. Also, all the power lines overhead are aluminum. It works great as long as its installed properly.

Comment / question: This is a 30A circuit, 240v, for direct wire appliance (HVAC compressor). And the aluminum wire is stranded, which I believe is standard for these types of instances. So, I assume the 30A you are referring to would be direct wire to an outlet like a dryer. Is a drier outlet considered a branch circuit? The dryer circuit with the 30A breaker in the box had solid copper.

I know, in my previous house, built in 1992, there was stranded aluminum wire used for a 40A (or maybe 50?) electric range.

 

[grsthegreat]

while you could run a 6/2 aluminum ser cable for a 30 amp ac unit ( as i recall thats the smallest aluminum romex style wire available - listed SER cable)very few people do. Until the craziness in prices kicked in a year and a half back, 10/2 copper was relatively cheap And inline with the cost of 6/2 Aluminum. Last week i paid nearly $400 for a 250 foot roll of 10/2 romex. I expect to see more aluminum runs out there soon.

ps: i edited my last post. That was supposed to say 15&20 amp circuits…not 30. Fat fingers.

 

[rbstern]

while you could run a 6/2 aluminum ser cable for a 30 amp ac unit ( as i recall thats the smallest aluminum romex style wire available )very few people do. Until the craziness in prices kicked in a year and a half back, 10/2 copper was relatively cheap And inline with the cost of 6/2 Aluminum. Last week i paid nearly $400 for a 250 foot roll of 10/2 romex. I expect to see more aluminum runs out there soon.

ps: i edited my last post. That was supposed to say 15&20 amp circuits…not 30. Fat fingers.

Got it. Thanks for clarifying on the 30A.

 

[grsthegreat]

Personally i just think the connections were loose. Do you recall if the screws on old breaker were tight? Should need quite alot of pressure to loosen.

 

[rbstern]

Personally i just think the connections were loose. Do you recall if the screws on old breaker were tight? Should need quite alot of pressure to loosen.

Two issues: Was working in poor lighting, and didn't have ideal tools at end (screwdriver blade was a bit too small). But, I do have the impression the carbon on the terminals made turning the screws harder, in either direction.

When I turned off the power to put the new replacement breaker in for the dryer, I was sure to have better lighting on hand (headlamp), and more appropriately sized tools. Made sure the screws in both circuits were firmly in place. I'll recheck the next time I happen to have business in the box.

 

[kenmac]

there are many homes where alum wire is run to A/C condensers.
Size of alum depends on the run and the circuit / load requirements.

 

[Tinhack]

I wouldn't use aluminum wire for anything--Even if the wire was free!

I remember back in the 80's when some builders started using aluminum wire. Many of the new homes burned to the ground. GM started using it in autos for the wire that runs to the rear of the vehicle. It was failing there too. If there's any chance of movement or vibration, it's going to fail. Typically with catastrophic results.

 

[jaxs]

Breakers do go bad. However usually when theres carbon buildup its due to wires not being tight on breaker. Aluminum wires are supposed to be torqued per spec on panel. Otherwise , if it were me, i would check tightness under every aluminum wire connection. Same contractor may not of tightened any of them.

loose wire causes arcing. Arcing creates carbon and heat. Heat trips breaker thermals.

Instead of trying to point out posts with varying amounts of poor information, I'll just say imo everything the above quoted poster said in his posts is correct. I cringe at the sight of electric questions due to the number that always respond with poor information. I commend op for the common sense approach to fixing the problem then seeking affirmation. I believe his actions are those of one who understands more than the average but is and will remain a student reaching for perfection.