Al Feeders

A

Alwayslearningelec

Senior Member
Location
NJ
Occupation
Estimator
First time I have comoe across this in spec. I think I'm going to price the AL conductors but the conduits/conductor sizes on the riser are based on Cu.

I know I will now have ot upsize the wire and conduit and keep in mind VD. Any suggestion for best way to go about this? I assume there could be a decent saving that could win me the job. Below is the extent of the feeder work. Maybe it won;t make that much of a diffference and I should bid it as designed.

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These guys are still specifying solid #10's. They should be flogged. :rolleyes:
Regarding your question sometimes you can install two sets of AL in a raceway if the original raceway for copper was oversized like say 4". We had a job where they changed design after some of the conduits were installed and we ended up with two sets of Al conductors in each raceway instead of one set of copper. Something like this:
Double Sets.jpg
 
infinity said:
These guys are still specifying solid #10's. They should be flogged. :rolleyes:
Regarding your question sometimes you can install two sets of AL in a raceway if the original raceway for copper was oversized like say 4". We had a job where they changed design after some of the conduits were installed and we ended up with two sets of Al conductors in each raceway instead of one set of copper. Something like this:
View attachment 2573507
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Wow...derating taken into consideration obviously?? What size wire? 4" pipe?

Also when I reference the table is chapter of NEC for maximum # of conductors it doesn't differentiate CU vs AL.
 
Alwayslearningelec said:
Wow...derating taken into consideration obviously?? What size wire? 4" pipe?

Also when I reference the table is chapter of NEC for maximum # of conductors it doesn't differentiate CU vs AL.
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Yes derating would apply. I think that those are 750's AL 4" EMT.

AL are usually different construction with compact stranding so you would use Table C1(A) for raceway fill and the numbers are different than TC1 that you would use for copper.
 
infinity said:
Yes derating would apply. I think that those are 750's AL 4" EMT.

AL are usually different construction with compact stranding so you would use Table C1(A) for raceway fill and the numbers are different than TC1 that you would use for copper.
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Guess that's 6 conductors in each pipe?
 
infinity said:
Who's money is it? If it's mine the EMT is good enough especially in the larger sizes.
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When you're at the sizes that couplings use 4 screws the whole argument about installer error gets very difficult to imagine. When the whole run in on strut or a metal building even more so.

For estimating purposes I still think it's good to price and plan for a wire equipment ground.
 
letgomywago said:
When you're at the sizes that couplings use 4 screws the whole argument about installer error gets very difficult to imagine. When the whole run in on strut or a metal building even more so.

For estimating purposes I still think it's good to price and plan for a wire equipment ground.
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A few years ago a friend set me some pictures of a busduct failure at a joint. The duct had been in service for about two years, but the pictures showed that the joint bolts had never been tightened. They were of the snap off head type and the red tags telling you to tighten them were still in place.
 
letgomywago said:
When you're at the sizes that couplings use 4 screws the whole argument about installer error gets very difficult to imagine. When the whole run in on strut or a metal building even more so.
Click to expand...
My point exactly. If you have 4" EMT and a big rack of conduits supported on strut even if you failed to tighten a few couplings there still wouldn't be a problem.
 
don_resqcapt19 said:
A few years ago a friend set me some pictures of a busduct failure at a joint. The duct had been in service for about two years, but the pictures showed that the joint bolts had never been tightened. They were of the snap off head type and the red tags telling you to tighten them were still in place.
Click to expand...
That's along the lines of someone not using wirenuts and just taping connections.
 
infinity said:
My point exactly. If you have 4" EMT and a big rack of conduits supported on strut even if you failed to tighten a few couplings there still wouldn't be a problem.
Click to expand...
letgomywago said:
When you're at the sizes that couplings use 4 screws the whole argument about installer error gets very difficult to imagine. When the whole run in on strut or a metal building even more so.

For estimating purposes I still think it's good to price and plan for a wire equipment ground.
Click to expand...


And this is why it drives me crazy when people are so black and white and make blanket statements like "I always pull a wire EGC". Ok so a smaller size conduit run on a nonconductive surface, perhaps it is prudent to run a wire EGC in that situation. But when you have parallel runs or just multiple conduits in a rack all strapped down, then we are getting into the wire EGC being a complete waste territory.
 
infinity said:
Yes derating would apply. I think that those are 750's AL 4" EMT.

AL are usually different construction with compact stranding so you would use Table C1(A) for raceway fill and the numbers are different than TC1 that you would use for copper.
Click to expand...
Do you have to specify compact or is that all they stock?
 
Hv&Lv said:
Do you have to specify compact or is that all they stock?
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infinity said:
All of the Al condcutors that we use straight from the supplier are compact strand construction. I don't even know if concentric stranded aluminum is available.
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Some of the aluminum conductors I get are compressed, not compact. They have a little space between the conductors so are a little larger. I can't remember if that was in a XHHW or a URD/USE/RHH
 
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