Thermostat wire needed

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I need about 30 feet of #18 - 8 conductor thermostat wire so I can add a humidistat to my system. But Home Depot and all the others only carry 7 conductor. And all the sources of 8 conductor wanna sell me a big spool. So, does anyone know where I can buy 8-conductor by the foot?
Would appreciate any help! Injun Ear
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Injun-ear wrote:

add a

carry 7

spool.
i'm not sure if this would be of help but the furnace company i deal with was more than happy to give me, at no cost, thermostat wire to relocate one on my own.
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if you do not find it, you could always run 2 - 4 conductor cables.... should be cheaper too.
m.

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Yes, I could... But figuring out what went where with the same colors would be a nightmare!!
Thanks anyway...

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Mark both ends of one cable and then run them. Magic marker would work great.
Deciphering becomes fairly easy from there.

spool.
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Run the 18-7, plus a 18-2 along with it. Easier to sort out than 2, 18-4's. Greg

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I believe any standard cat-5 cable has 8 wires in it.
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Yes, but it's a lot smaller than18 gauge, and it doesn't have the same color coding as thermostat wire. The latter isn't too much of a problem, as long as the OP pays attention to his connections, but the former might be: the resistance in cat-5 cable will be considerably higher than in 18ga thermostat wire.
-- Regards, Doug Miller (alphageek at milmac dot com)
Nobody ever left footprints in the sands of time by sitting on his butt. And who wants to leave buttprints in the sands of time?
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On Wed, 11 May 2005 21:17:13 +0000, Doug Miller wrote:

Correct. It's usually 24 AWG.

Wrong. The resistance is exactly the same (near zero ohms). What's different is the current-handling capability, which is completely different than resistance.
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Dan,
No the resistance is NOT the same. That is why the current handling capacity is different. Your meter is not sensitive to small fractions of an ohm, but the relays he is controlling ARE if the wire is long enough and the voltage is marginal. You could get a reference book on wire and it would give you the ohms per thousand feet. It is different for every gauge of wire. Then calculate the fraction of 1000 feet that yopu are using to get the total ohms. Remember to measure the total length, not just what you are adding. Then double it because the current has to flow both ways, out in one wire and back in another.
Stretch
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On Wed, 11 May 2005 18:34:30 -0700, stretch wrote:

I'll agree that (theoretically) there is a small variation in resistance between bigger/smaller wire. However...... in this application, which has a very short length, and a small difference in wire gauge, that is NOT the reason for current handling differences. It is the diameter (gauge) of the wire that makes that difference. Just like a larger water pipe can handle more flow. Same thing. Only so many electrons can pass through a given diameter of wire in a given amount of time. Larger diameter means more current, and it's not because of any difference in resistance.
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And the *reason* that makes a difference is that the larger the diameter, the lower the resistance.
Sheesh.

Which is, of course, another way of stating that the *resistance* of a wire depends on its diameter.

Of course it is *exactly* due to the difference in resistance.
-- Regards, Doug Miller (alphageek at milmac dot com)
Nobody ever left footprints in the sands of time by sitting on his butt. And who wants to leave buttprints in the sands of time?
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I E =---- R
I don't think this formula applies where he lives....
wrote:

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I hope it doesn't!!! Ohm's Law is: V = I * R. That is, voltage- across equals current-in times resistance-of. Also, current is not limited by cross section in the several-amp currents we are talking about here. Rather, for a given size wire the current is proportional to the voltage between its ends. --Phil
Oscar_Lives wrote:

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And resistance varies inversely with the square of the conductor diameter.

And to the length of the wire. Further, the constant of proportionality is different for different sizes of wire.
"Dan C" claimed that the resistances of 18- and 24-ga conductors are identical. That is patently false.
-- Regards, Doug Miller (alphageek at milmac dot com)
Nobody ever left footprints in the sands of time by sitting on his butt. And who wants to leave buttprints in the sands of time?
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The first thing to observe, when attempting to correct someone else, is to make sure that you first have your _own_ facts straight. You unfortunately omitted to do this.
Far from being "exactly the same", the resistance of a 24ga conductor is more than _four_times_ that of an 18ga conductor of the same length.
Nor is it "near zero ohms" in either case, except for unusual values of "near" or "zero".
Finally, it is precisely the resistance of a conductor (along with the properties of its insulation) that determines its capacity to carry current.
18ga wire: 0.00751 ohms/ft = 0.225 ohms in 30 ft (length cited by the OP) 24ga wire: 0.0302 ohms/ft = 0.906 ohms in 30 ft
http://www.epanorama.net/documents/wiring/wire_resistance.html
-- Regards, Doug Miller (alphageek at milmac dot com)
Nobody ever left footprints in the sands of time by sitting on his butt. And who wants to leave buttprints in the sands of time?
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--------- Any electrical supply or HVAC supply house in your area should be able to help you.
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Well, yeah, but they want to sell me a 250-foot roll when I only need 30 feet. They don't sell by the foot. And Cat-5 cable is #24, too small to handle the power.
Injun Ear

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On Wed, 11 May 2005 16:26:11 -0600, "Injun-ear"

-------- Sorry to hear that. They don't sound very friendly.
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All the humidifiers I have installed use 18-2. Haven't seen one yet that requires 8 conductor.

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