#6 NM wire in 1/2" hole?

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On Friday, August 1, 2014 7:54:14 AM UTC-4, snipped-for-privacy@yahoo.com wrote:

I'm surprised it took this long for someone to post this, which is wrong. Breakers for equipment with motor loads are not sized like a circuit for receptacles or a heater. It's perfectly permissible to have a 50A breaker on an #8 gauge wire for an AC. The overcurrent protection is in the eqpt and it's rated for that installation.
I agree with Gfre, whoever wrote that manual, wherever they are located, (China?), doesn't know what they are doing. Proof that they don't is clearly demonstrated by them calling for 3 conductor cable, while they really mean 2 conductor plus ground. Another very curious thing that I've never seen before, look at what goes from the outside unit to power the evaporator unit(s) that shown in the posted link. And in the spec they call that 4 conductor. What they are showing looks like 3 conductors plus ground, all used. So, what they are clearly showing is a 240V only connection coming in to the outside unit, then a 240V connection *with neutral* leaving it to power the evaporator(s). That seems *very* strange to me.... It seems like they have established their own neutral, unconneced to the service neutral, going to the other units. Any thoughts Gfre?
Regarding the conductor sizing, I agree with Gfre. The spec sheet says 26A min circuit ampacity. The rated power input is 4600W max. Based on that, 10g would be sufficient. Does this thing have backup resistance electric heat by any chance? I doubt it because it's not in the spec sheet. If it were my install, I'd go by the rating plate. At 26A, I'd just bump it up to 8g, 2 conductors. If anything, I'd say the big honking cable with an extra unused conductor is more likely to draw an inspectors attention, because it looks odd and likely a DIY.
In most places this should have a permit. Why not write down what's on the eqpt tag and take that, the manual, and the spec sheet and go ask the inspector?

Wrong.

And wrong again. 6-2 is TWO conductors, plus a ground. The ground is *not* a conductor.
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trader4 says: " It seems like they have established their own neutral, unconneced to the service neutral, going to the other units. "
My assumption is that this is not a self-establised neutral, but the wiring control (from the indoor evaporator) that tells the outdoor condenser to switch from A/C to heat pump.
Side note: kind of strange to me that the indoor units are 220VAC. Call me paranoid, but I wouldn't have minded a true neutral and only 120VAC to each indoor unit.
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On Friday, August 1, 2014 9:44:01 AM UTC-4, snipped-for-privacy@yahoo.com wrote:

I was thinking of it strictly in terms of power and the fact that in the diagram, that wire is marked N(1). Marking it N and having it wired right there with the two hots, sure strongly suggests it's a neutral. Do they talk about what that N(1) means at all?
But if those wires are the only link between the outside and inside eqpt, then I agree signalling would have to go on it. It's even possible it serves both functions, but if it's like you're suggesting, it makes sense electrically. But if it's signalling, I wonder what code says about that? ie, combining signalling, which would normally be low voltage with 240V? I guess it they use 240V to do the signalling, then it's OK, but they couldn't AFAIK use 24V or similar.
Regarding using 240V to run the evaporators inside the house, I'd have no problem with that. In Europe, many places, 220 is standard receptacle voltage. Also, something many folks miss, it's pretty hard to wind up with 240V going through you. You'd have to make contact with *both* hot legs. Far more likely is standing in water, touching ground and one hot, in which case, it's still 120V.
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trader4 says: " It seems like they have established their own neutral, unconneced to the service neutral, going to the other units. "
My assumption is that this is not a self-establised neutral, but the wiring control (from the indoor evaporator) that tells the outdoor condenser to switch from A/C to heat pump.
Side note: kind of strange to me that the indoor units are 220VAC. Call me paranoid, but
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On Fri, 1 Aug 2014 06:42:25 -0700 (PDT), snipped-for-privacy@yahoo.com wrote:

The mini splits are usually "inverter" designs so they do generate their own voltages in the unit. I bet the voltages going to each inside unit are not line voltage at all. The ones I have use a low voltage (24 or so)
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On Friday, August 1, 2014 10:46:28 AM UTC-4, snipped-for-privacy@aol.com wrote:

Interesting. I just assumed line voltage in, line voltage out, which I guess it isn't. As you point out, all they really need is power for the fan and a communications link of some kind, so how they do it is up to them.
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On Fri, 1 Aug 2014 08:20:53 -0700 (PDT), trader_4

These mini splits usually use low voltage to the inside units. They are only spinning up a fan, maybe a vane direction motor and the controller. My Fujitsu says I could use bell wire if I wanted to.
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On Fri, 01 Aug 2014 00:32:34 -0400, snipped-for-privacy@aol.com wrote:

excede 80% of the circuit protection rating (fuse or breaker - and I assume wiring). Also, if I remember and read correctly, the specification is for a "stranded" wire - which "generally" should be sized up 1 size. So up one from 10 because it is over 80% circuit capacity, and up one for stranded would be a #6 stranded cordWhich would explain the recommendadation - and would allow a #8 solid conductor. Still. not hurting anything but the pocketbook using #6, and using 3+ground instead of 2+ground is costing a lot more than the guage upgrade. Remember - it was talking about a "3 conductor stranded cord" - which is black/white/green. Using solid cable that is 2+ground - black, white, and bare.
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On Fri, 1 Aug 2014 04:54:14 -0700 (PDT), snipped-for-privacy@yahoo.com wrote:

read either way. And many air conditioner installations do spec flexible cable between the house (disconnect) and the unit. 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)
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On Friday, August 1, 2014 11:41:20 PM UTC-4, snipped-for-privacy@snyder.on.ca wrote:

No it can't. The ground is not referred to as a conductor, by code, by the manufacturer, or by anyone who knows what they are doing. Go look at a box of Romex. It's sold as 14/2, 14/3, with ground. That is either two or three conductors plus ground.
And many air conditioner installations do spec

Please show us some examples, I've never seen one.

Wrong again. The eqpt is marked for a circuit with a minimum ampacity of 26A. A 30 Amp circuit exceeds that.
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On Fri, 01 Aug 2014 23:34:13 -0400, snipped-for-privacy@snyder.on.ca wrote:

That is not what the label says or what it means. If you look at the U/L marking guide, you will see the 80% is built into that "minimum circuit ampacity" I bet the design FLA is more like 19-20a and the actual max you would ever read with an amp probe is more like 15-16 in normal operation They say strange numbers like "26a" to keep you out of 12ga which is rated for 25a in the 60 and 75c column. The marking guide and the label itself is clearly saying 10 ga copper.

Cite that. Table 310-16 does not make that distinction
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On Saturday, August 2, 2014 12:40:28 AM UTC-4, snipped-for-privacy@aol.com wrote:

+1
This is a specific piece of eqpt on a dedicated circuit. It's not a circuit for receptacles. The rules are different. Just like a previous poster thinks you can't have a 50A breaker on 8g wiring for an AC, when you can, because the rules are different.

Yes, I'd like to see that too. AFAIK, solid and stranded of the same gauge have the same current carrying capacity, unless this AC is connected to a 1Mhz power source, or similar where skin effect comes into play.
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snipped-for-privacy@snyder.on.ca wrote in

Wrong. The 80% rule applies only to continuous loads.
You really should stop trying to give electrical advice.
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snipped-for-privacy@snyder.on.ca wrote in

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.
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On Sat, 2 Aug 2014 05:51:37 -0700 (PDT), trader_4

Yup, you set a guy's hair on fire if his knowledge stops at the Time Life "electric for dummies" book. There are places where you can have 12 gauge wire on a 50 and 14 on a 40. It is a common question on the inspector tests. (typical was, 1HP 120v, 16 FLA motor on a 40a breaker with 14ga copper)

Yup, the stranded is actually better if you start getting up in the higher frequencies. You can see the effect at 400hz which used to be pretty common in computer rooms. (back when they actually had real computers in there) ;-) The big 400hz cables were usually fine stranded.
If you look at table 8 you will see that the DC resistance of stranded #10 is actually 0.03 ohms more than solid per 1000 feet but that is insignificant for this calculation and the difference is a little less at 60hz
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On Sat, 2 Aug 2014 14:05:32 +0000 (UTC), Doug Miller

Air conditioners are such a specific load that it really requires an engineer to specify the circuit ampacity and over current protection. That is why the U/L marking guide specifies this on the label.
Motor loads are subject to the 80% rule but that is 125% of the nameplate FLA and you use table 310.16 to determine wire size, not 240.4(D)
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On Sat, 02 Aug 2014 00:40:28 -0400, snipped-for-privacy@aol.com wrote:

I'll stick to that. I like to see stranded power cords for high amperage applications - like Generators and table saws- upsized one size over what I would use with solid copper.
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On Saturday, August 2, 2014 3:33:07 PM UTC-4, snipped-for-privacy@snyder.on.ca wrote:

You see outside permanently mounted AC condenser/compressor units on power cords much up there?
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On Sat, 2 Aug 2014 14:05:32 +0000 (UTC), Doug Miller

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??
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
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On Saturday, August 2, 2014 3:51:59 PM UTC-4, snipped-for-privacy@snyder.on.ca wrote:

It would seem if you're giving out the advice, you should know that no? And if not, googling "code definition continous load" should work.
What minimum duty cycle is

That doesn't matter, because per Gfre, all that has been taken into account by the engineers who designed and rated the eqpt. The eqpt rating plate is what governs, it says a circuit with minimum ampacity of 26A, which you then use to directly determine the wire size.
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