Why is this happening?

[davedottcom]

208 Volt 3phase HVAC Condensor keeps "melting" the breaker! Actually it looks more like it is arcing at the breaker/phase bar contacts until the plastic heats up & crumbles away. (3RD time now!)
First time the breaker lasted 1-2 years, now they only last about 2-3 months!

Unit Specs:
Min Cir Amps: 43
Max HACR Breaker: 50

It's wired with #6 THHN on a 3-pole 50 amp breaker. Maybe 25' run, if that.

Each of the 3 legs are pulling around 31 amps.

HVAC guy checked out the unit, said it was fine. I cleaned off the phase bar (It was actually still in great shape) put a new 3-pole breaker in, unit works fine again...for about 2 months! Then I get another call... it happened again!

The breaker is Very warm to the touch after only 15 minutes of use.

I confirmed the unit is 208 according to the spec. sheet on the unit.

I called the manufacturer...got the run-around... "you need to call the distributor", so I called the distributor, "you need to call the manufacturer"...



Any suggestions?

Dave

 

[physis]

Re: Why is this happening?

There obviously is heat at the breaker.

I'm think there's too much resistance at the breaker somewhere and it's turning into heat. I don't why. But if the current is less than the rating of the breaker that's all I can think of.

 

[dirkhats]

Re: Why is this happening?

Sounds like you do not have a bolt on circuit breaker, but it is a plug in breaker. I suspect it is the connection between the buss bar and the circuit breaker. (even though you said you cleaned it) I would get another new breaker and install it in an entirely different spot on the buss bar that has not gotten warm. Do not clean the buss! Find a good spot instead. If this doesn't work, install a bolt-on panel.

 

[davedottcom]

Re: Why is this happening?

Nope, not bolt on. It is an Old Sylvania GTE panel. I keep installing Cutler Hammer BR breakers (I was told they are the accepted replacements now) Although the first time it happened it was a Seimens breaker so I wouldn't point the finger at CH.

I cleaned the phase bar after the first incident. Used a wire brush just enough to knock off the dust... I didn't damage it!

 

[davedottcom]

Re: Why is this happening?

What's that guey stuff on the contacts of some new breakers?

What's that stuff for?

 

[celtic]

Re: Why is this happening?

Originally posted by davedottcom:
What's that guey stuff on the contacts of some new breakers?

What's that stuff for?

Penatrox/Nolax

 

[paul]

Re: Why is this happening?

Do you have a chart recorder you can put on the circuit to monitor it for 24-48+ hours to see what's going on?

 

[davedottcom]

Re: Why is this happening?

Wish I did Paul.

But it is now officially on my Christmas List!

 

[dillon3c]

Re: Why is this happening?

Dave,
I have seen in your original post,it doesn't call for a fuse size,rather a HACR type breaker.

If no fuse,then HACR rated would be needed..

Is this, what is installed now?

[ August 10, 2005, 09:49 PM: Message edited by: dillon3c ]

 

[benaround]

Re: Why is this happening?

Dave,

Did you happen to check the contactor inside of the unit? They are usually the cheapest possible,and at 43a,starting could be over 250a.I know you said the HVAC guy looked it over but the contacts would be easy to miss.Also the contacts if damaged would set up a high resistance and not trip the c.b., It's got to be somewhere?

frank

 

[davedottcom]

Re: Why is this happening?

Dillion, I think it actually does say fuse or HACR breaker. But No, there are no fuses & Yes the Breakers are HACR.

Frank, No, I didn't...I bet you are right. That would make sense. I'll check it out tomorrow.

Thanks,

Dave