Al Feeders

[Alwayslearningelec]

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.

 

[infinity]

These guys are still specifying solid #10's. They should be flogged.
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:

 

[Alwayslearningelec]

These guys are still specifying solid #10's. They should be flogged.
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

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.

 

[infinity]

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.

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.

 

[Alwayslearningelec]

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.

Guess that's 6 conductors in each pipe?

 

[infinity]

Guess that's 6 conductors in each pipe?

Yes.

 

[augie47]

Guess that's 6 conductors in each pipe?

From your print it appears they require an EGC. Be sure to include that in your fill calculations

 

[Alwayslearningelec]

From your print it appears they require an EGC. Be sure to include that in your fill calculations

Will do, thanks. In other cases the conduit could be used as a EGC, correct?

 

[ggunn]

Will do, thanks. In other cases the conduit could be used as a EGC, correct?

This sort of question sometimes touches off a lively discussion of "can" vs. "should" metal conduit be used as EGC.

 

[Alwayslearningelec]

This sort of question sometimes touches off a lively discussion of "can" vs. "should" metal conduit be used as EGC.

Oooops. Sorry..lol. Should it be? That's what I would like to know.

 

[infinity]

Oooops. Sorry..lol. Should it be? That's what I would like to know.

Who's money is it? If it's mine the EMT is good enough especially in the larger sizes.

 

[letgomywago]

Who's money is it? If it's mine the EMT is good enough especially in the larger sizes.

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.

 

[don_resqcapt19]

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.

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.

 

[infinity]

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.

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.