help selecting wire to relocated ac condenser

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Old 03-19-13, 01:52 PM
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help selecting wire to relocated ac condenser

I have 6/3 from the panel to the exterior shut-off for the condenser. I need to move the condenser from the rear to the side. I need to cut the wire inside the finished basement, add a junction box, and a new wire out the side.

About 12 ft will be exposed to the elements because of the location, and 5-7 ft above grade.

I cannot read all the markings on the 6/3 stranded aluminum wire , but I think it says "type 3 style u type xmmw".

I will not be installing the new condenser, but it will save me $300 if I put in the junction box and get the new wire in place ready for connecting. (tricky and time-consuming so worth my while to do it)

Should I use 6/3 stranded aluminum exterior grade? and do I need to run it in a conduit even though it will be at least 5 ft up?
Would appreciate any suggestions --thanks,
cap1816
 
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Old 03-19-13, 03:50 PM
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If you are sure what you have is aluminum, stay with aluminum, but be sure you use adequate amounts of Morris (or other) anti oxidant compound when you make your connections. Depending on how long it has been there, I don't think you have aluminum, but I may be wrong. You will need to run individual conductors in conduit using LB's and other related connections from your junction box to the pull disconnect at the new location.
 
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Old 03-19-13, 06:52 PM
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I think it says "type 3 style u type xmmw".
Could that be Type SE Style U? And, could it say XHHW? I believe you have aluminum service entrance cable; Type SE Style U with XHHW conductors.

http://www.southwire.com/ProductCata...rodcatsheet273

If it is run 5 feet up, it probably doesn't need to be sleeved in conduit unless it is subject to physical damage.
 
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Old 03-19-13, 08:59 PM
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Chandler,
I thought the aluminum was used to avoid oxidation. The old wire has been there 15 years and looks almost new -- no obvious oxidation.

Do you think LBs are necessary since it come out of the basement 5-1/2ft above grade and slants up to about 7 ft above grade?
thanks for your help
 
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Old 03-19-13, 09:07 PM
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Is your intention to splice that cable inside and continue back outside with a similar product or do you plan to run a conduit outside now ?

If you come outside with a conduit then you would need an LB.

Aluminum wiring is used because it's cheaper.
 
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Old 03-19-13, 09:34 PM
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PJmax,
Yes, I plan to cut the cable where there is an access panel in the basement ceiling, so I don't have to cut into the drywall. Then I will put in a junction box to hold the old and new wires, and feed the new wire outside the house. At that point it will take about 12 ft horizontally to get to the new condenser location.

It will be a minimum of 5.5 ft above grade at its lowest then up to 7 ft. Unfortunately, the horizontal run has two odd angles - 33 and 57 degrees, so I was hoping to avoid conduit. What do you think?

thanks, cap1816
did not know the reason for aluminum was cost -- learn something new every day
 
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Old 03-19-13, 10:03 PM
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You are working with some larger wires there. You're going to need 4 bugs to splice the wires and anti oxidant grease for the actual splices and connections. Service cable should be ok for what you are doing but it must be well supported. You will probably need a 4-11/16" square junction box to splice those wires in.

I'm guessing you are adding a new piece from the junction box inside to the disconnect box on the outside. You should consider using copper between the disconnect and the compressor unit. Some manufacturers require copper only to the units. That can be discussed with the installer.

In the two pictures below the copper unit on the right is a split bug.
The right hand picture is a set screw splice.

I'm partial to the set screw splices. After splicing..... the three splices get taped up. The bare ground splice doesn't need to be taped.

You can also get Polaris bugs. They look like the setscrew splices but they come in a rubber housing and don't require any taping.
 
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Old 03-20-13, 06:15 AM
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Number 6 cable is huge to run to an outside unit. Many A/C units are just fine with #12 or #10. Check the dataplate on the unit.
 
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Old 03-20-13, 03:11 PM
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PJmax,
The set screw looks very secure, so I will try to find them or the polaris-type. Thanks for mentioning them.

Yes, the old aluminum wire will terminate in the junction box on the basement ceiling. The new wire will come from this inside junction box to the outside disconnect.

The wire from the outside disconnect box to the condenser will be selected by the installer -- I assumed copper, but I will verify that.

But would it be okay for me to use copper from the old aluminum to the disconnect? I was concerned about using two types of metal and how they might interact.

But if that is not a problem, I will use copper with anti-oxident and the secure connectors.
Would it be ok to connect the two metals in an interior junction box?

thanks for all your help,
cap 1816
 
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Old 03-20-13, 03:46 PM
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pcboss,
It is large, but the circuit breaker/panel is 75 ft from the condenser. It has a double pole of 60. And the condenser has a lot to cool -- it is a 5 ton.

According to the specs,
the minimum circuit amperes is 39/39
the minimum breaker is 50/50
the maximum breakers 60/60

I did not see any wire size listed.
Does #6 still seem the wrong choice? Not well versed in electrical matters -- which I why your help is appreciated--
cap1816
 
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Old 03-20-13, 07:47 PM
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You could use #8 copper or the #6 aluminum.

The wire is based on the minimum circuit ampacity, in your case 39. You would then look to find a wire that was rated for 39 amps or more.
 
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Old 03-20-13, 09:55 PM
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You can switch from aluminum to copper at the basement junction box. When splicing the two wires you should use the screw type splices. Use anti oxidant on the aluminum wire. The copper does not need it.

The switch to #8 copper is almost the equivalent of using #6 aluminum. Since you hadn't planned on running conduit. You would have to switch to UF-B 8/3 w/ground.

You asked if the #6 was over sized ........ it's not......it's actually borderline.
 
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Old 03-21-13, 07:56 AM
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pcboss,
Thanks, I think I will switch to copper
cap1816
 
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Old 03-21-13, 08:00 AM
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PJmax,
Thanks for the clear instructions. I have one last question. If 6-aluminum was borderline, then is 8-copper borderline as well since it seems to be equivalent?

Should I use a 6-copper between the junction and the shutoff?
again, thanks for all your help
cap1816
 
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Old 03-21-13, 08:54 AM
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Yes...... #6 to the disconnect would be a better choice.

However.....it's going to be tough getting it into a connector to go into the box and disconnect.
 
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Old 03-21-13, 10:24 AM
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Thanks for the warning -- I will check that before I purchase
thanks for all your help
cap1816
 
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Old 03-21-13, 10:24 AM
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If 6-aluminum was borderline, then is 8-copper borderline as well since it seems to be equivalent?
Because the melting point of aluminum is lower than the melting point of copper, copper is usually the preferred choice.
 
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Old 03-21-13, 10:31 AM
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more information always welcome -- thanks for the explanation
cap1816
 
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