# Aluminum Wire to feed RTU



## bmac55343 (May 16, 2014)

I asked an RTU manufacturer if they had lugs that would accept aluminum wire. They said not to run aluminum to their unit because it is "Prone to arcing". I have seen information in IAEI saying that AA-8000 series is as good as copper if terminated correctly and coated with anti-oxidant. Why would I not be able to use aluminum to feed a rooftop unit?


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## AU Facilities (Mar 25, 2015)

There isn't a reason..... as long as it's sized right.

That being said when they say "Prone to arcing" they are most probably referring to the fact that a lot of times the connections are not done properly and no one ever does any PM on the connection over the years. Since aluminum tend to expand and contract more then copper and then causes the lug to become loose which creates said arcing and causes damage which the company does not want to deal with. So saying they want copper conductors is easier for them.


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## MechanicalDVR (Dec 29, 2007)

Are you feeding an internal CB in the unit or a disco and then into the unit? Is this an AAON unit by any chance?


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## Bird dog (Oct 27, 2015)

IMO only with crimp connectors.

http://www.hubbellpowersystems.com/catalogs/connectors/DF.pdf


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## MechanicalDVR (Dec 29, 2007)

Many units have Sq D breakers inside as a means of disconnect and they are marked AL/CU. The units that have European din breakers aren't AL/CU.


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## bmac55343 (May 16, 2014)

Its a Daikin unit and the rep is the one saying it. It will come with a disconnect switch.


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## MechanicalDVR (Dec 29, 2007)

bmac55343 said:


> Its a Daikin unit and the rep is the one saying it. It will come with a disconnect switch.


Yup, you may find the lugs for wire in that disco are actually steel and not aluminum or copper.


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## Tonedeaf (Nov 26, 2012)

You will void the warranty of most RTU manufacturers if you use aluminum conductors.

Open up the instruction book and look at electrical hook ups it will say cooper conductors only.


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## Big John (May 23, 2010)

I would use aluminum wire and copper pin-crimps in a heartbeat.


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## 99cents (Aug 20, 2012)

If the manufacturer says don't do it, don't do it. Put in copper and charge it back. If it's a hard bid, whine and grovel.


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## MechanicalDVR (Dec 29, 2007)

Stop the aluminum in a JB below the roof and go up to the unit with copper.


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## Signal1 (Feb 10, 2016)

Over the years most HVAC manuals I've seen say "Use copper wire only".

If that's what the rep said, I would just do it that way. 

If you don't, any future problems will be.... "The electricians fault".


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## Cl906um (Jul 21, 2012)

The last one I did said to use copper only. Since it came with mechanical lugs to terminate, I just taled copper to ilsco insulated splice blocks to my aluminum. It had plenty of space at least to do this.


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## Tonedeaf (Nov 26, 2012)

I wouldn't chance it, you are going to get some asshole from TRANE, Carrier, Diaken....... telling the building owner that a compressor is fried and blames the electrician for using AL conductors.


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## Cow (Jan 16, 2008)

Tonedeaf said:


> I wouldn't chance it, you are going to get some asshole from TRANE, Carrier, Diaken....... telling the building owner that a compressor is fried and blames the electrician for using AL conductors.


I can see that being a very real possibility, despite all of us on here knowing that isn't the case, assuming you size the AL conductors properly.


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## papaotis (Jun 8, 2013)

AL conductors, properly 'greased' and torqued are no more problem than an Cu conductor properly torqued . why is there so much argument over this when everyday we deal with copper wire terminated in aan AL bar with a steel screw? disimaler metals being a problem, my ass!


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## RePhase277 (Feb 5, 2008)

I have a translator app on my phone. I'll pull it up and post the results here:

"Aluminum wire will cause arcing."

Translation: "Copper is more forgiving than aluminum for poor terminations. Some other sucker in the past used aluminum and didn't know what he was doing. When the unit burned up, we caught the blame."


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