Power mains question: wire gauge

On Thu, 03 Jan 2013 12:33:52 -0500, snipped-for-privacy@aol.com wrote:


If you place a pipe, then a fitting and then another pipe, it will be a single, integrated unit.
I do not know what you think it is I suggested, but all I refer to is that you can assemble the piping in place. It is easier (in some cases) to walk ten or twenty 8 foot segments down a wire bundle than it is to feed the wire bundle down the entire 200' run.
The finished result is exactly the same.
As far as 'build then string wires' goes, I think it is pretty stupid and more than a bit too much of the too many chiefs syndrome.
The chance of nicking a line (in metal pipes) is greater for a pulled wire than my suggested method. I sure would be interested to know what they are crying about. I can see where it would cause a problem on runs which are enclosed in buildings (if even possible to do), but an open buried run should be easy to do my way, and even better in some instances.
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On Thu, 03 Jan 2013 19:50:00 -0800, SoothSayer

Too bad you aren't king huh?
The fact still remains the NEC says you build the system and then you pull the wire in. If you ever want to replace the wire with another configuration you will understand why. I also wonder how you keep the PVC cement off the wire if you use RNC.
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On Fri, 04 Jan 2013 00:31:30 -0500, snipped-for-privacy@aol.com wrote:

I do understand. I know all about serviceability issues.
This is a single, STRAIGHT run with zero mid-span junction breaks. It would be fine. Ahhh... forget it.
Dang. Just buy 12/2 UG Nomex, bury it at 18" and forget the pipe.
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On Thu, 03 Jan 2013 22:09:44 -0800, SoothSayer

AEE fans (Should I tell him that is 24?")
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On Fri, 04 Jan 2013 01:15:35 -0500, snipped-for-privacy@aol.com wrote:

My old Cable TV days. Their burial depth requisite is 18". (at least in Ohio)
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On Thu, 03 Jan 2013 23:00:13 -0800, SoothSayer

You were talking about UF, not TV cable
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On Sat, 05 Jan 2013 00:37:53 -0500, snipped-for-privacy@aol.com wrote:

Right. but in reference to my mistake, I was explaining why.
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On Sat, 05 Jan 2013 00:35:10 -0800, SoothSayer

No problem. The advantage of using PVC conduit is that you can bury it 18" instead of the 24 you need for UF. The other is the ability to change your mind without needing a shovel Personally I would run 3/4" instead of the more common 1/2" because it is easier to pull the wires in, you can put bigger wire in the pipe and the cost differential is minimal. The labor is the same.
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wrote:

He decided it was 3hp
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wrote:

That is true. The NEC motor tables in 430 have been unchanged since the Howdy Doody days. Motor technology has marched on.
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Not

below

2%

lugs.

It depends on several variables, including motor size, motor winding class, number of phases, design of motor start system, and some other things. Very small motors may start at 2x FLA, some very large (full voltage start) motors may require 20 to 30 x FLA.
?-)
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ote:

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In North American Practice the electrical codes forbid assembling conduit around wire. The conduit must be built as a complete assembly and then you pull the wire from pull point to pull point.
--
Tom Horne

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snipped-for-privacy@invalid.net says...

There is s thing called "voltage drop". Voltage will drop in a wire running a long distance, sometimes so much, the device at the end will not operate!
The amount of voltage drop depends on the voltage, the type of metal used for the wire (copper / aluminum), the wire size, and the load in amperage at the end of that wire.
The internet has made this easy for you. Just search google.com for the words...
Voltage Drop Calculator
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Bill explained :

The supply voltage has no bearing on the voltage drop. Only the wire size, the wire material, the run length (there snd back) and the load current affect the voltage drop in any line.
The supply voltage is required in those calulators only to allow the calculation of the percentage drop from the original supply not the actual volts lost.

--
John G



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200' of 14AWG solid copper wire has a resistance of about 0.5 ohms, so if your locked rotor current is 15A, then the drop across the cable will be 7.5V when the motor first starts up, leaving 212.5V for the motor. No problem.
If your motor is about 80% efficient, then at full load it'll be taking about 466 watts from the mains, which is about 2.1A.
2.1A through 200' of 14AWG ohm will drop about 1.1V across the run, leaving about 219 for the motor. Absolutely no problem with 14AWG, so don't waste your money on what you don't need.
--
JF

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DaveC wrote:

YES!!
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