Now That Ain't Cool

Home Inspector with JRV Home Inspection Services, LLC HOI 394

Cool sunCool has for generations of young and old alike pretty much means basically the same thing. From the Fonz to Ferris Bueller cool means popular, awesome, groovy, wicked or fly. When something ain't too cool, it's not okay.

With the temperatures in the 90s lately here in Connecticut, cool also means staying cool and that means air conditioning. Central air is popular here, all though not in use for more that three to four months a year, many house's have a system.

Part of my routine for checking the outdoor compressor is to look at the units data plate and open the service switch next to the unit. In the summer opening the box first without knocking can have me running. The reason for looking inside the service switch is to check the wiring. Most often, all though simple, the wiring is done by the installer, not an electrician.

A/C compressor service switch with cover removed

Sometimes mistakes are made.

Opening a service switch recently, it was deja vu all over again. What I saw was a very toasted neutral (white) wire. The reason a wire gets a nice tan or worse cooked, is from too much resistance. To prevent a wire from have too much amperage potentially flowing through it, the wire must be appropriately sized for the job. In addition the wire must be protected by a matching sized circuit breaker. So a 20 amp wire must be protected by a 20 amp breaker.

Toasted neutral wire inside an A/C compressor service switch boxWith A/C compressors things get a bit counter intuitive. That is why there is the manufactures data plate. It's not a great read, but it has all the necessary and important information on how to properly wire the unit. With A/C compressors the wire is always smaller than the breaker. This is because when the unit starts there is a temporary surge of electricity. The engineers who design these things know this and put a minimum wire ampacity on the data plate. The thing about engineers is if nothing else they are very precise.

This unit had a minimum wire ampacity of 31.9. Everyone knows you round down if the number is under five.

Except with electricity. Less is never a good practice.

The fried wire attached to the terminal was rated at 30 amps.

And that ain't too cool.


Posted by

James Quarello
Connecticut Home Inspector
Former SNEC-ASHI President
JRV Home Inspection Services, LLC

 ASHI Certified Inspector

To find out more about our other high tech services we offer in Connecticut click on the links below:

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Serving the Connecticut Counties of Fairfield, Hartford, Middlesex, New Haven, Southern Litchfield and Western New London.


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Charles Stallions Real Estate Services
Charles Stallions Real Estate Services Inc - Gulf Breeze, FL
Buyers Agent 800-309-3414 Pace and Gulf Breeze,Fl.

We seem to have a unit a week going out and the service people want to replace not repair.

Jul 06, 2012 10:15 PM #1
Kathryn Maguire (757) 560-0881 - Chesapeake, VA
Serving Chesapeake, Norfolk, VA Beach

And this is the time of year when those units are being put to the test.  Definitely not cool!

Jul 06, 2012 10:21 PM #2
Clint Mckie
Desert Sun Home, commercial Inspections - Carlsbad, NM
Desert Sun Home, Comm. Inspection 1-575-706-5586

Hi James,

I have only seen this a couple of times.

I would recommend a licensed electrician to do the after install repairs.




Best, Clint McKie

Jul 06, 2012 10:21 PM #3
Shannon Milligan, Richmond VA Real Estate Agent/Associate Broker
RVA Home Team - Richmond, VA
RVA Home Team - Winning with Integrity.

With heat reaching 105 here in Richmond VA, our units have really been put through the test. One of my clients has a dual zone 1 1/2 ton each unit for a 1600sqft house and the second floor will only get to about 85 degrees. Checked with several companies who told me that is adequate size for the size of the home but still they can't seem to find the problem. Fighting with home warranty company on this as well. Got them to send someone today at 9am. We shall see what they come up with this time. Two days ago they just pumped it full of freon and said it was in fine working order. Anyway, I found your blog informative and appreciated the timing of it as I am helping my client through this!

Jul 06, 2012 10:28 PM #4
Diane Daley
Caron's Gateway Real Estate - Northumberland, NH

AC's are a wonderful thing when working properly,  Thanks for sharing, I always get ideas for inspector's blogs

Jul 06, 2012 11:14 PM #5
Andrea Swiedler
Berkshire Hathaway HomeServices New England Properties - New Milford, CT
Realtor, Southern Litchfield County CT

Jim, amazing when we all know that those units are installed by a professional.... just sayin....

Jul 06, 2012 11:46 PM #6
Charles Buell
Charles Buell Inspections Inc. - Seattle, WA
Seattle Home Inspector

Jim, I have been hearing that you guys need air conditioning recently :)

Jul 07, 2012 01:25 AM #7
Donald Hester
NCW Home Inspections, LLC - Wenatchee, WA
NCW Home Inspections, LLC

Jim, We are finally having summer here (we will be in the 100's this weekend) so we should see a bunch of AC  Units and Heat pump go poof ; ) Had one go poof yesterday and it was not even that hot yet, low 90's.

Jul 07, 2012 01:35 AM #8
Jay Markanich
Jay Markanich Real Estate Inspections, LLC - Bristow, VA
Home Inspector - servicing all Northern Virginia

A couple of recent s'mores posts!  Toasted marshmallows and such!  What, they undersized the wiring?  Say it ain't so, Joe!, um Jim!

That wiring was force of habit.  Everyone knows compressors always get 30s.

Jul 07, 2012 08:18 AM #9
James Quarello
JRV Home Inspection Services, LLC - Wallingford, CT
Connecticut Home Inspector

Joyce, Maybe it's time to replace if they are breaking down so often.

Kathryn, Definitely not cool at all :)

Clint, I always recommend an electrician for wiring.

Shannon, I would agree, two units of that size should be enough. A couple of thoughts; Hows the insulation in the house? Or the duct work for the units, are there enough return vents and if so are they well placed.

Caron, Thanks. I like to share :)

Andrea, Amazing indeed.

Charlie, And you guys are close to needing heat :)

Don, 100s!? I think Charlie needs some of that heat across the way :)

Jay, Must,ve been habit... a bad one ;)



Jul 09, 2012 10:43 PM #10
Robert Butler
Aspect Inspection - Montreal West Island, QC
Montreal Home Inspector | Aspect Inspection

When you need air conditioning, whays one more hot thing?

 "Most often, ..................the wiring is done by the installer, not an electrician." You called it Jim, that's it in a 'twitter' or a 'tweet' or something.

We got the heat today!

Jul 14, 2012 06:54 AM #11
James Quarello
JRV Home Inspection Services, LLC - Wallingford, CT
Connecticut Home Inspector

Robert, Thanks, its been and will continue to be hot here too. 

Jul 15, 2012 11:51 PM #12
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