DIYbanter - View Single Post - What size wiring for Central A/C compressor?

dpb

On 3/4/2013 8:46 PM, wrote:
On Mon, 04 Mar 2013 16:55:43 -0600, The Daring Dufas
wrote:

....

... I
have to install what I know the inspector will pass and the inspectors
do look at the temperature rating of the wire and check if the circuit
breaker is HACR rated if it's hooked to an AC condensing unit. I don't
argue with the inspectors, you can if you wish. O_o

You have to look at the whole code, in context, you can't just cherry
pick one article and believe that is the way it works in every
situation.
When you are looking at an AC unit you start in 440 if you are sizing
the breaker, not using the label.

440.22 Application and Selection.
(A) Rating or Setting for Individual Motor-Compressor. The
motor-compressor branch-circuit short-circuit and ground-fault
...[Code detail elided for brevity]...

12 ga wire has an ampacity of 25a in the 60c column so you can start
with a 45a breaker and you might end up with a 60 if you use the round
up rule at 225%.
The label is actually rounding down to get to 40a.

The label is very unambiguous. It tells you can use 12ga wire and a
40a breaker. If an inspector is confused about that, he is
incompetent. I am not saying there are not incompetent inspectors out
there but at a certain point they need to be educated. That probably
does not happen on an active job but you can send a letter to the
state licensing authority asking for a ruling. Fix it for everyone,
not just that job.

+about5

If the inspectors in this area are this bad, they're costing a lot of
money over time for no reason (other than perhaps kickbacks from the
local distributors???)

When first in TN years ago there was an incompetent so widely known that
it was a standing joke. The locals put up w/ it and just bought
innumerable pints of Old Turkey (from which you can imagine the joke).

I finally got fed up enough and being new to the area was willing to be
the one who pulled his plug by documenting it and making the complaint.
In the end, was _much_ "more better" all around...

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