Another question on aluminum cable

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  #1  
Old 05-19-06, 07:33 AM
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Another question on aluminum cable

I just read the aluminum wiring thread and got scared. I was going to bury an aluminum direct burial cable 2-2-2-4 between main disconnect and pump panel. I know I have to scrape the ends off with a wire brush and use antioxidant paste. Isn't that enough?

I have no experience with aluminum cable/wire. Do you suggest I stay with copper? Please advise where I can buy copper direct burial cable, say 4-4-4-6 or 2-2-2-4. The only reason I chose aluminum 2-2-2-4 was because Lowes sells it. Thanks.
 
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  #2  
Old 05-19-06, 08:47 AM
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> I just read the aluminum wiring thread and got scared.

Whatever you read, it wasn't applicable to your situation.

> I was going to bury an aluminum direct burial cable 2-2-2-4
> between main disconnect and pump panel.

That's fine.

> I know I have to scrape the ends off with a wire brush and
> use antioxidant paste. Isn't that enough?

That's plenty. I cut the aluminum back to where it is shiny.
The brush is to work the paste into the grooves, not to shine it up (though you could; but starting with no corrosion at all is better than trying to remove it).

> Do you suggest I stay with copper?
No reason in your case.
 
  #3  
Old 05-19-06, 09:05 AM
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I would never install direct burial cable for a number of reasons, but that's just me.

The cable you describe has almost nothing in common with the #12 and#10 branch circuit wiring that causes lots of problems. The cable is different right down to the insulation processes used and the aluminum alloy. Correctly installed the cable is completely safe.

If you haven't bought this cable yet I'd suggest you bury conduit and pull individual conductors. And if you absolutely think you have to use copper, have the paperwork for a second mortgage in place - the price of copper is out of sight right now.
 
  #4  
Old 05-19-06, 10:28 AM
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The main reason I didn't want to bury PVC pipe and pull individual wires is my neighbor's comment. According to him, "in our area," underground conduits get filled with water so quickly. (I suppose it is bad.) He suggested direct burial. Another reason, I can bury a cable for 100' by myself. It seems to be simpler. (By the way, I have not buried cable or pulled wire before. I have no prior experience to compare to.)

Please let me hear if I had better bury PVC and pull wires. Thanks.

Trenching is no problem in our area. It's all sand.

Thank you.
 
  #5  
Old 05-19-06, 10:34 AM
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All conduit underground gets filled with water. It does not matter where it is. The advantage of conduit is that you change the wires later if you need to without digging.
 
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Old 05-20-06, 06:12 AM
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Conduit is a long term solution, costs a few $ more initially and costs nothing down the road.

Actually, when you price direct bury vs THWN + conduit, the price might be closer than you think.
 
  #7  
Old 05-20-06, 09:24 AM
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Right now the path for buried cable is not covered. But it will be soon. I can see the advantage of burying a conduit. Before I get further with this plan, please let me know if it's okay to leave the conduit filled with water. Thanks.
 
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Old 05-20-06, 09:37 AM
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When you install the conduit it will be dry. As air circulates through the conduit and condenses and as water permeates the seams, the conduit will eventually fill with water. This is normal and you need do nothing about it.
 
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Old 05-20-06, 02:00 PM
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If the run has one end much higher than the other, the water level can rise above ground level at the low end.

You can put weep holes and gravel at the low end underground.
This will usually prevent water from rising very high if this is a concern.
 
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Old 05-20-06, 02:27 PM
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Originally Posted by bolide
If the run has one end much higher than the other, the water level can rise above ground level at the low end.

You can put weep holes and gravel at the low end underground.
This will usually prevent water from rising very high if this is a concern.
WEEP Holes!? In the sweeps?

Can't you just make the connections correctly ?
 
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Old 05-20-06, 02:45 PM
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Originally Posted by lectriclee
WEEP Holes!? In the sweeps?
Didn't say in the elbow (just somewhere at the low end) and won't recommend that because it could snag a fish tape or conductor.


> Can't you just make the connections correctly ?

Please explain what you mean.


In some cases the conduit goes up the electric pole, is open at the top, and conductors run straight in from the transformer with no drip loop. Does your local poco use a weatherhead on a utility pole? None do around here. I don't recall ever seeing one anywhere.
 
  #12  
Old 05-20-06, 05:21 PM
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I have hundreds and hundreds of direct burial number 2 alum like you are talking, its one of the best bargains in wiring, lots of power for the least money. I have dug them up even and rebury, 20 yrs in the ground and looks as new as the day it went in. Your power company uses it all the time as direct burial, toss it in 24 inches, legal and good to go. I cant see a big reason to worry about pulling a new wire, this is highly reliable, its why they invent it and list if for this application. Poco doesnt pipe it so they can pull a new wire, why should you?
 
  #13  
Old 05-21-06, 05:47 AM
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avoid alum conductors underground!

install polyethylene pipe 8" below ground & pull wires thru that -- available in 50, 100 @ HomeDepot & Lowes -- 500ft & 1000ft = plumbing distributor -- bring ends up above gn

then install any "w" rated wite -- THWN --

be sure devices at each end are rated for use with alum. use oxide inhibitor after abrading with stainless steel wire brush --

be sure to connect grounding wire to well casing & pump housing! you may need a grounding rod there also.

if in country, get a surge protector to be close to the pump!
 
  #14  
Old 05-21-06, 05:57 AM
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Cem - poly pipe 8" below the surface won't cut it here. Local code requires at least 18".

Bob - I'm a little confused about PVC pipe leaking at the seams. Why would electrical PVC be any different than plumbing DWV? I can understand water entry from openings above ground, I might even buy a bit of condensation, but if the PVC joints were properly made up, they shouldn't leak.
Out of curiosity, I just stuck a snake through the buried PVC I installed 3 years ago between my house and garage. I wish my basement was as dry as my conduit.
 
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Old 05-21-06, 07:20 AM
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=cem]

install polyethylene pipe 8" below ground & pull wires thru that -- available in 50, 100 @ HomeDepot & Lowes -- 500ft & 1000ft = plumbing distributor -- bring ends up above gn
Not allowed by NEC. Unless some local or state jurisdiction does not follow NEC, (there are some that may opt out some parts of code) it won't fly anywhere.
 
  #16  
Old 05-21-06, 09:27 AM
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If properly made, PVC joints won't leak. However, I have seen people make the joints in less than an optimal manner.

As regards the condensation. This is always an issue. It is more of an issue where the humidity is worse, but it is an issue everywhere.

But even so, regardless of what you might see in reality, conduit outside is considered a wet location and requires conductors rated for same.
 
  #17  
Old 05-21-06, 05:15 PM
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some more arcaic rules!
using PE & THWN was what I recommended for wiring pumps in the middle of aerating ponds for years -- but, inquiry came from industrial & utility customers of Anaconda Wire & Cable -- it works! [but, since I think of it, none were probably #2 in size --]

PE is tough & in long lengths, so one does not have to worry about joints leaking -- it is a mechanical protective device for the wire.

yes, for that size wire, 18in is correct -- 12 ok for 20a in residences -- 1&2 family

I still would not use alum -- I'v seen too many troubles with alum cables lightly loaded or no load, yet energized. quite dependent upon soil condition, insul & jacket properties!
 
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Old 05-21-06, 05:47 PM
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yes, for that size wire, 18in is correct -- 12 ok for 20a in residences -- 1&2 family
and if gfci protected, otherwise it goes back to 18 inches

I still would not use alum -- I'v seen too many troubles with alum cables lightly loaded or no load, yet energized. quite dependent upon soil condition, insul & jacket properties!
Could you expand upon this a bit. What was happening?
 
  #19  
Old 05-21-06, 06:56 PM
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Thousands and thousands of these are installed every day and he has the advantage of doing it himself and the number one thing to consider about this job isnt the kind of wire, alum or copper it if it is adequately sized and this likely is depending on pump and distance. How many instals you figure each day in the country by contractors use this wire when it comes out of a quoted job like those crappy tract homes with a 30A direct burial to the garage? This wire seems ok when a sparky, with a licence is buying it out of his pocket. Everytime it comes up with a homeowner he all of a sudden has to have copper. Its about like telling a kid he has to have SnapOns to work on his minibike. That 2-2-2-4 is great for installs like this, cant be beat. Its comparitively cheap, easy to bury, you can afford a big enough wire to do the job, it comes as 4 wire all sized and marked, you can feed it with 100 if you have to but works excelent with 60A breakers even on longer runs to residential garages. I wire a dozen garages when I was a kid with this setup 25 yrs ago, never had one call back with a rotted wire. Bury it at legal depth, 24 inches. Its as cheap, as good, as safe and as practical as it can be done especially where a guy is doing it himself.
 
  #20  
Old 05-21-06, 06:57 PM
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Duplicated for some reason.
 
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