Need help/suggestions....

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c2500

Senior Member
Location
South Carolina
On a new home, I spoke with the HVAC company to verify the amperage of the equipment the were providing. Everything was fine except one minor detail. The Trane unit in the attic was to be 40 amps. I ran 8/2. When I was sticking the wire into the machine yesterday, I read the data plate. It reads the minimum ampacity is 45 amps, minimum and maximum breaker is 45 amps. I know NM is rated at 90 degrees (45 amps), but the breaker being 75 degrees knocks it down to 75 degrees (40 amps). The actual load is 32 amps for the heat strips and 4.3 amps for the fan motor.

Any input (such as something I have missed in the code) or should I just run new #6 wire and duke it out with the HVAC company? (The info was actually written on a stud and there may be a picture, and the HO witnessed it all as he is owner/builder)

Thanks,

c2500
 
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220/221

Senior Member
Location
AZ
I'd look the other way unless it was sure to be caught on inspection.

If there was a chance that it would be caught, I'd confer with the HO and the HVAC guy. I'd give them my opinion on the matter (let it go) but also tell them I wouldn't be held financially responsible for the change.

If there was no inspection, I wouldn't think twice about it.

If it was #8 SE or thhn, it would be fine. In the real world I don't think there is any real difference in the capacity of the different types of wire/cable.
 
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c2500

Senior Member
Location
South Carolina
In reality, it will not be caught on inspection. (Based off of the HVAC ones so far) Sadly, I am a code thumper. The HO/Builder wants me to let it go. HVAC company is not aware at this time.

Also, we are 05 NEC.

c2500
 
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ohm

Senior Member
Location
Birmingham, AL
c2500 said:
On a new home, I spoke with the HVAC company to verify the amperage of the equipment the were providing. Everything was fine except one minor detail. The Trane unit in the attic was to be 40 amps. I ran 8/2. When I was sticking the wire into the machine yesterday, I read the data plate. It reads the minimum ampacity is 45 amps, minimum and maximum breaker is 45 amps. I know NM is rated at 90 degrees (45 amps), but the breaker being 75 degrees knocks it down to 75 degrees (40 amps). The actual load is 32 amps for the heat strips and 4.3 amps for the fan motor.

Any input (such as something I have missed in the code) or should I just run new #6 wire and duke it out with the HVAC company? (The info was actually written on a stud and there may be a picture, and the HO witnessed it all as he is owner/builder)

Thanks,

What you described happens to me all the time. I ask the HVAC guy for his requirements and rough-in what he says. If he changes his mind I have to eat it, at the final. Clearly, you must use the 60 deg collum for NM so #8 is only good for 40A, per 334.80. Lots of luck w/ the HVAC guy. They don't act dumb..they are dumb. I can't even get them to check the block on their unit which says what heater they installed.
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electricmanscott

electricmanscott

Senior Member
Location
Boston, MA
ohm said:
What you described happens to me all the time. I ask the HVAC guy for his requirements and rough-in what he says. If he changes his mind I have to eat it, at the final..
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Yeah, that makes sense. :rolleyes:

As for OP, if you want to make right you know what needs to be done and who has to pay.

Nm ampacity is based on 60 degrees.
 
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ohm

Senior Member
Location
Birmingham, AL
c2500 said:
OOOOps, minor correction...we are now under 2005 NEC. This job is under 2003 IRC...2002 NEC. Codes shifted July 1.

c2500
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334.80 applies for the 02 & 05 code ...40A. Around here the inspectors go straight to the air handlers, like a duck to water.
 
LarryFine

LarryFine

Master Electrician Electric Contractor Richmond VA
Location
Henrico County, VA
Occupation
Electrical Contractor
ohm said:
What you described happens to me all the time. I ask the HVAC guy for his requirements and rough-in what he says. If he changes his mind I have to eat it, at the final.
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I never have. I like to argue too much.

I can't even get them to check the block on their unit which says what heater they installed.
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Same here, but I tell them they have to.
 
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c2500

Senior Member
Location
South Carolina
I have no intention of eating it. This is not their only screwup. They set the (3)condensors such that we had to run conduit every which way to get the right disconnect to the right machine instead of opening the disconnects to see what size wire was in them. The only alternative they have will be to reduce the heat strip size...which will open another can of worms. Fortunately, there is a partial path still available to run wire from attic to the basement. Some minor drywall repair and it will work.

Oh I can hardly wait for tommorow morning......

c2500
 
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ohm

Senior Member
Location
Birmingham, AL
c2500 said:
I have no intention of eating it. This is not their only screwup. They set the (3)condensors such that we had to run conduit every which way to get the right disconnect to the right machine instead of opening the disconnects to see what size wire was in them. The only alternative they have will be to reduce the heat strip size...which will open another can of worms. Fortunately, there is a partial path still available to run wire from attic to the basement. Some minor drywall repair and it will work.

Oh I can hardly wait for tommorow morning......

c2500
Click to expand...

Might be a good time to show up with all your crew & football buddies. Good Lick..I mean luck!
 
weressl

weressl

Esteemed Member
Location
Texas by the Gulf, geat crab, great shrimp
c2500 said:
On a new home, I spoke with the HVAC company to verify the amperage of the equipment the were providing. Everything was fine except one minor detail. The Trane unit in the attic was to be 40 amps. I ran 8/2. When I was sticking the wire into the machine yesterday, I read the data plate. It reads the minimum ampacity is 45 amps, minimum and maximum breaker is 45 amps. I know NM is rated at 90 degrees (45 amps), but the breaker being 75 degrees knocks it down to 75 degrees (40 amps). The actual load is 32 amps for the heat strips and 4.3 amps for the fan motor.

Any input (such as something I have missed in the code) or should I just run new #6 wire and duke it out with the HVAC company? (The info was actually written on a stud and there may be a picture, and the HO witnessed it all as he is owner/builder)

Thanks,

c2500
Click to expand...

Since it is in the attick do you also use the ambient adjustment?
 
2

220/221

Senior Member
Location
AZ
They set the (3)condensors such that we had to run conduit every which way to get the right disconnect to the right machine instead of opening the disconnects to see what size wire was in them.
Click to expand...

HVAC question. Are line sets different sizes for different size units?

If so, they were likely in place before you did your rough in ;)
 
scwirenut

scwirenut

Senior Member
Location
Sumter, South Carolina
I would just simply put a 40amp breaker on it. If it ever trips then just tell them you provided what they asked for, a 40amp circuit. anything else should then be decided by them. they can pay you to install larger, or lower heat strips, their call, either way dosnt affect you.
 
C

c2500

Senior Member
Location
South Carolina
220/221 said:
HVAC question. Are line sets different sizes for different size units?

If so, they were likely in place before you did your rough in ;)
Click to expand...

No. The line sets were into the basement, where they stopped. They had the ability to run them wherever they wanted. They completed the line sets after the disconnects where there. They were lazy anyway, they could have made 3 holes for the line sets, but instead used one hole for the two large line sets (Tranes), and another hole for the small Sanyo unit. In fact, they were made to come back and sleeve the line sets for the Sanyo because the just blew through the brick and left them in a very rough hole.
 
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