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LynnX 01-14-2013 10:44 AM

HVAC condenser not wired properly?

I had an electrician come out to inspect my panel and provide an estimate for some additional circuits. He noticed that the HVAC condenser was connected to a 40A two-pole breaker with #10 wire (2x#10 w/G).
He stated that #10 wiring should be protected by 30A breakers, that a 40A circuit should use #8 wire, and that the present condenser wiring may be dangerous and a serious violation of the NEC.
The HVAC system is a recent upgrade/replacement for a 33-year-old system. The original condenser wiring was used to connect the new condenser. Sometimes the original 30A breaker has tripped.
The installer sent out a service technician who replaced the original 30A breaker with the current 40A breaker. It has not tripped.
The electrician recommended that I have another HVAC company inspect the HVAC wiring and determine what should be done. He would then be happy to provide an estimate of the cost to repair any sub-standard wiring.
The identification sheet on the condenser shows the following information:
LENNOX M/N: XC17-048-230-03
Electrical Rating: 1 PH, 60 HZ
Nominal Volts: 208/230 Min 197 Max 253
Compressor PH: 1, RLA: 21.8, LRA: 117
Fan Motor PH: 1, FLA: 2, HP: 1/4
Min. Ckt. Ampacity Amperage Minimum: 29.3
Max Fuse or Ckt. Bkr. Fusible/Coupe Circuit (HACR per NEC): 50
Can anyone determine from the above information if the condenser is not properly wired and/or not wired to Code?
Thank you for your time and expertise,

joecaption 01-14-2013 12:07 PM

Without also up grading the wire to a #8 what they did was wrong and againt code.
The wire can melt before the breaker ever trips.

beenthere 01-14-2013 04:20 PM


Originally Posted by joecaption (Post 1093269)
Without also up grading the wire to a #8 what they did was wrong and againt code.
The wire can melt before the breaker ever trips.

No, what they did is allowed by code. The wire meets the min ampacity required. And the breaker is sized within the max allowed by data plate. NEC also allows the breaker to exceed the data plate if the unit has problems starting.

Check the motor load only section of the NEC, you'll see its allowed.

Mr.HVAC 01-14-2013 10:00 PM

Beenthere is correct, what the hvac company did is correct.

Min. Ckt. Ampacity Amperage Minimum: 29.3 - means the running amp on compressor or the wire size for the condensor. #10 wire is rated for 30amp which is higher than 29.3, it's good. The compressor has its own thermal overload protection.

Max Fuse or Ckt. Bkr. Fusible/Coupe Circuit (HACR per NEC): 50 - means the starting amp on compressor. maximum breaker can be 50 amp, 40 amp breaker is ok as long as it does not go over 50 amp, and beenthere is right if the breaker keeps tripping, they do allow a little higher as long as it isn't larger than 225% of the circuit rating or compresser rating, whichever is larger.

Everything your HVAC Did is corect even if they were to keep the 30amp breaker as long as it doesn't trip the breaker. Can you use a #8? Absolutely, but not neccessary according NEC.

Do us a favor and tell your electrician to worry about his trade and not someone elses. If he still argue print this link out and give it to him.

sorry, not being an ass to the electrician, But I had a same similary problem with a handyman that caused me to wasted my time going back and forth.

LynnX 01-15-2013 08:50 PM

Hey beenthere and Mr. HVAC. Thank you very much.

I have been scratching my head about how I can run a line between my panel and the condenser -- no conduit, no crawl space, no attic, no way without a pain-in-the-butt-round-about path. I am very relieved. Thank you, thank you!!!


jbfan 01-15-2013 08:57 PM

Home inspectors site this all the time, and I make pretty good money by going out and explain that this is allowed.

TexasDave 01-23-2014 04:52 PM

A year later let me chime in and ask a question. I have an Amana RHE48A2D heat pump and the 40 amp circuit breaker (outside unit) which has been working fine for about 12 years has started tripping. I figured it was getting weak and I replaced it with another circuit breaker. I also bought a new dual run capacitor for this thing and replaced that also. The new circuit breaker also tripped, so I bought a third. It is tripping intermittently.

I checked the running amp draw on both legs, and it is between 15 and 19 amps. So I am guessing it is tripping at startup, but only occasionally. I'm stumped at this point. I also am guessing from what I read above that replacing the 40 amp breaker with a 50 (8 gauge wire) would be safe and within code. But given its history, I'm wondering why the change? Would a hard-start kit do any good??

Thanks in advance for your expertise! :)


beenthere 01-24-2014 03:48 AM

Try the hard start kit first. Thats an old unit you have. Back when Amana actually was Amana.

TexasDave 01-24-2014 06:26 PM

Any particular reason why condenser units get harder to start with age? It would seem like as parts get more clearance and more bypass gasses, they would become easier to start, not harder. Hmmmm...

beenthere 01-24-2014 08:40 PM

Bearings can become looser, or tighter with age.

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