On Saturday, August 2, 2014 8:09:08 PM UTC-4, wrote:
On Sat, 02 Aug 2014 17:06:41 -0400, wrote:
On Sat, 02 Aug 2014 15:59:53 -0400, wrote:
On Sat, 02 Aug 2014 15:51:59 -0400, wrote:
On Sat, 2 Aug 2014 14:05:32 +0000 (UTC), Doug Miller
wrote:
wrote in :
And remember - if the unit draws a constant 26 amps, it is over-spec
for a 30 amp circuit (maximum 80% rated current for continuous use)
The term "continuous" has a clear, specific definition in the Code -- and an air conditioner
does not meet that definition.
You really should stop trying to give electrical advice.
OK - what does "continuous" mean? What minimum duty cycle is
required for it to be "continuous"? How long does the air conditioner
run on the hottest day of the year? Is the running current not
"continuous" in this case? Starting amps don't count. Do you KNOW what
the steady state running current of the AC unit in question is??
Continuous is 3 hours in the NEC.
My assumption is the AC unit would draw 26 amps for more than 20 min
utes at a time, up to full time operation, it is to be connected with
a 3 conductor (including ground) flexible stranded cable.
Your assumptions are no more valid than mine, whatever they are -
unless you KNOW what current the unit draws and KNOW it will never
approach 100% duty cycle
It is really not even a factor here. The "minimum circuit ampacity" is
an engineered value based on that particular piece of equipment and
takes into account all applicable factors.
In this case a 10 gauge copper wire will fulfill that requirement.
So why does the instruction specify a #6??????
If the manufacturer's UL listing spec requires a #6, it doesn't meet
code to connect with a #10.
I just went bact to the OP's post. I quote:
"Hi, I'm the OP.
Yes, the mini split a/c system specs explicitly call for a 50amp
breaker and #6 AWG (although I shudder to think that it'll actually
use that much, with a 16 SEER)."
What does the code say about over-protecting a cable?
The cable is protected by a 50 amp breaker. Going by "general code"
you cannot run an AWG10 circuit on a 50 amp circuit.
OMG, here we go again. Gfre went through that days ago. I did
too when yesterday someone started in with the same nonsense.
The 15 amps for 14g, 20 amps for 12g, 30 amps for 10g rules
works for lights and receptacles.
It doesn't work for motor and compressor loads. You can indeed have
a 50 amp breaker on 10g wire because the overcurrent protection in
the AC load is in the AC. The breaker is there to protect against
short circuits and it needs to be 50A to handle the brief startup
current.
What specifics outside of the "general code" would allow the cable to
be protected with an over-rated protection device?
The rest of the code that covers motors, HVAC compressors, etc.?
And yes, the air conditioner in my house is connected with stranded
flexible conductors from the house to the outside unit - run through
weatherproof flexible conduit to the "protected disconnect" - a
weatherproof single circuit circuit breaker enclosure.
And you call that a *cord* up in Canada? Around here we call that
THWN run in liquidtight.
The outdoor unit sits on a plarform of concrete blocks on a base of
concrete patio stones, and is not bolted down.. Been that way for over
40 years. (except the original unit sat right on the patio stones, I
raised the unit on concrete blocks to keep it out of the dirt and
leaves when I had the unit replaced.
You see any up there that use #6?, especially a minisplit that's just
3.7 toms? If it needed that much power it would be such a pig that
it could not be sold because it wouldn't meet the min SEER standards.
That's the nutty part about this. Just from practical experience it's
obvious that #6 is a mistake.
And back to the original issue, here's another way of looking at it.
You're looking in the wrong end of the telescope. You're trying to
analyze the load, apply rules and then size the circuit. The engineers
already did that. They put "min circuit ampacity 26A on the UL label.
That means the load is saying, "Hook me up to a circuit capable of
supplying 26A or more."