ECN Electrical Forum - Discussion Forums for Electricians, Inspectors and Related Professionals
ECN Shout Chat
ShoutChat
Recent Posts
12 Lead Motor Connection Weird
by emolatur - 01/19/22 02:40 PM
Any women electricians here?
by gfretwell - 01/17/22 01:44 PM
Well There's your problem.
by gfretwell - 01/08/22 12:17 AM
Happy New Year!!
by HotLine1 - 01/04/22 09:50 AM
Sangamo s309.2
by Robski - 12/31/21 04:54 PM
New in the Gallery:
240/208 to a house
240/208 to a house
by wa2ise, October 9
Now you know.
Now you know.
by Tom_Horne, September 7
Who's Online Now
0 members (), 41 guests, and 17 robots.
Key: Admin, Global Mod, Mod
Previous Thread
Next Thread
Print Thread
Rate Thread
Page 1 of 2 1 2
Joined: Oct 2013
Posts: 3
A
New Member
Hi Everyone,

I had an electrician out a couple months ago to install a new breaker box. Just recently, my air conditioner stopped working and I had an A/C guy out who diagnosed the issue as a burnt out compressor. He said that the compressor was supposed to only have 40 watts(?) and the fuse that it was connected to was delivering 50. Is this the electrician's responsibility for not checking that the fuse was compatible with my air conditioning unit?

Thanks for the advice,
Adam

Joined: Apr 2002
Posts: 7,288
Likes: 4
Member
Good Afternoon:
I can explain this briefly:
The manufacturers nameplate on the HVAC CU has a minimum and maximum amperage listed for that specific model.

The maximum overcurrent (fuse or circuit breaker) is not to be exceeded. Also note that some units specify 'fuses only'.

More than likely, when your panel was changed, the electrician installed new circuit breakers sized to match the existing ones in the old panel.

You mention 'fuse'; but do not mention the circuit breaker that feeds the circuit from the panel.





John
Joined: Apr 2002
Posts: 7,288
Likes: 4
Member
I was going to lock this thread, but I will leave it up for a while.



John
Joined: Mar 2004
Posts: 947
T
twh Offline
Member
Oversized overcurrent doesn't burn out motors and overcurrent protection doesn't protect against overload. Overcurrent protection on a motor (or compressor) protects the wires if there is a failure on the circuit. The overcurrent will trip if the motor is locked but the motor has to be locked first.

I call bs on the oversized overcurrent burning out the motor. I say the locked compressor tripped the breaker. It's the A/C guy's fault.

Joined: Oct 2013
Posts: 3
A
New Member
The A/C was not working first. So that's when we called the A/C guy. We already had the A/C before the breaker box was installed. The A/C guy didn't do anything, he just ruled out all the other things and found a dead compressor.

Joined: Nov 2005
Posts: 826
J
Member
That's quite a smart AC guy who knows what took out that compressor. He must have a BS degree. I had a guy BS my aunt that way once. He very eloquently defended his BS actions while he refunded her $$$.
Joe

Joined: Mar 2004
Posts: 947
T
twh Offline
Member
The solution was to replace the compressor so the compressor must have been the only problem.

If the A/C guy had to replace something else and the compressor, there might be a chance a smaller breaker could have saved the compressor if the "something else" might have caused the compressor to stall. If the something else just caused the compressor to overload, its internal overload protection should have handled that. Breakers don't protect against overload.

The A/C guy said the reason the compressor failed is that the breaker was too big, I have to wonder what motivated that. I don't think that idea will fly.

Sometimes compressors fail.

Still the breaker should be properly sized to protect the conductors. You might be able to stick the electrician with that cost. He relied on the guy before him to properly size the breaker. Maybe you can get the original installer to pay for the breaker.

Joined: Mar 2004
Posts: 947
T
twh Offline
Member
Oh, and about the title to the thread "new breaker box blew out my a/c", that sounds really ... uninformed. The "who pays?" part makes it sound wilful.

Joined: Jul 2002
Posts: 8,412
Likes: 3
Member
Hi there,
Did the A/C guy actually state HOW the compressor was faulty?
Usually, the guy would need to put a megohm meter on it to check the winding resistances to ground and the actual winding resistances themselves, did he provide you with any test results after coming to that conclusion?

It isn't unusual for compressors to fail because of a voltage spike, no CB or fuse will ever protect against something like that, I've seen this happen quite a few times
You didn't state how old the A/C unit was in your OP?

I would find it pretty tenuous to blame an A/C unit failing because of a panel upgrade.

Joined: Sep 2002
Posts: 917
Likes: 1
N
Member
The A/C tech has to blame someone, the compressor has overloads, the fuses or circuit breaker is just for short circuit protection.

Page 1 of 2 1 2

Link Copied to Clipboard
Featured:

Tools for Electricians
Tools for Electricians
 

* * * * * * *

2020 Master Electrician Exam Preparation Combos
2020 NEC Electrician
Exam Prep Combos:
Master / Journeyman

 

Member Spotlight
AllClear
AllClear
Belmond Iowa US
Posts: 44
Joined: August 2005
Top Posters(30 Days)
NORCAL 3
Robski 1
Popular Topics(Views)
287,962 Are you busy
220,093 Re: Forum
206,091 Need opinion
Powered by UBB.threads™ PHP Forum Software 7.7.5