Cu/Al question


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Old 08-29-05, 07:15 AM
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Cu/Al question

I recently replaced the contactor in my outdoor condensing unit. Because the 8 AWG supply wire was too big to fit under the contactor terminal screw (even with the strands separated so that half of them went under each side of the screw), I decided to use an L-shaped lug to connect the wires to the contactor. (The lug uses a screw, not crimping, to secure the supply wire to the lug.) The lug is aluminum, but is rated Cu/Al. The supply wire is Cu. The packaging for the lug did not say anything about using Noalox or something similar, so I didn't. Is this okay?
 
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Old 08-29-05, 02:08 PM
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I find it odd that a unit that needs #8 wire cannot handle that size wire. Is your contactor the correct size?

#8 is good for 40amps.

As for your question of using DE-OX on the wires I highly recommend it. The problem is not your lug if it is a CU/AL rated lug. The problem is moisture causing the wire to corrode.
 
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Old 08-29-05, 02:22 PM
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Well, I don't think the unit actually needs no. 8 wire (since the compressor's FLA is 19.2), but that's what the original installers used. The contactor is a 30A, and it is the right one (although the factory installed contactor was 25A, the parts house had only 30 and 40). As far as corrosion goes, this is a 21-year old unit that had the original contactor (which I replaced as PM), and there was no corrosion (although I did cut and strip the wires to get a fresh end). So I should still use the Deox?
 

Last edited by eclipse; 08-29-05 at 02:47 PM.
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Old 08-29-05, 02:27 PM
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On aluminum wire we always use it. Better safe than sorry.

With your FLA at 19 your fine.
 
 

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