Need help, Aluminum versus Copper Question

[stang623]

I am sorry to ask this question as I have seen it in my searches, looks like people use aluminum all the time. But wondering if it is ok for my specific application.

I am familar with electric in terms of hooking up 3 phase equipment and 277 volt lighting installation, recently the business has moved to a new location which has a 5000 amp service at 480, which is crazy large for us. We probably need around 500 or so at this time. During the 90 days of due diligence the building was robbed of many of the large copper service lines. The previous owner did not care at all about this building and it is everything to us.

So we are in process of trying to get the lights back on so we can start moving in, we have met with a contractor on installing one of the 600 amp sub panels. Problem is that everyone wants to run copper wires back to this sub panel and I would really prefer the cost of aluminum. It is about 450 ft from the switchgear, at least whoever stole the copper left us functioning switchgear I guess. It looks like they have dual 3.0" EMT conduit running to the location of the 600 amp panel. I am wondering if this is possible in aluminum...seems like if we had to run larger conduit it would still be much cheaper than running copper for this size, at least according the rough calc's i did. I am not expert though and would like to hear what you guys have to say. The contractor said there was no way they could pull aluminum wire that far and thought they would have to increase the conduit size. It is pretty simple just an L shape run. With two 90 degree elbows in run.

Is it possible without a lot of extra effort?

What sizing would you do? I would prefer to size it slightly over 600 amps rather than slightly under. I was thinking parallet 400's in copper or parallel 600's in aluminum and figuring a 80% derating for 4-6 conductors in conduit.

Let me know if you need further information, we want to set this up right for something we can grow into. Anything special with aluminum, I saw something about crimped ends in one of the post's i read.

 

[Jraef]

To get the same ampacity in the conductors, aluminum must be larger than copper. It might still be a little cheaper for the wire itself, but will be more difficult for the installer to handle, which usually means higher labor cost. The conduit size issue may be real as well; larger conductors = more fill, which may require larger conduit. To be honest, most good electricians already know from experience which way is better for a given capacity and situation. Trusting your chosen contractor is most likely your best choice.

 

[infinity]

Although it's not a code requirement at 450' you should be concerned about voltage drop. With 600 kcmil XHHW Al you can fit 4 conductors in each 3" EMT which give you 680 amps worth of conductors. Not sure about the VD, someone will chime in.

Pulling aluminum is generally easier than the comparable size copper conductors.

 

[JFletcher]

Welcome to The Forum. sorry about your copper Thief experience, which if the building is still not secure, what's to keep it from happening again with the new contractor?

when you say 90s, do you mean sweeps or junction boxes /LBs? It doesn't really matter I suppose. If your neutral is not a current-carrying conductor, I would look at pulling in two sets/conduit of 4 / 0 or 250 MCM aluminum, depending on what your actual load will be. 450 ft with just two sweeps in it is not exactly a difficult pull imo.

Metal prices are always changing however with this installation I think the cost of copper over aluminum is way higher than any additional labor to install it.

 

[Barbqranch]

Aluminum is vastly cheaper if new copper gets stolen but new aluminum doesn't.

 

[petersonra]

Al works just as well as Cu. It's a little bigger for the same ampacity.

2X 500 kcm would give you 620 amps if you use aluminum.

HOWEVER, I would suggest this. Start by doing an actual NEC load calculation and seeing what it says. You might be surprised at what it will require.

I think the contractor is right about being able to get 4 500 KCM wires in a 3" EMT. Probably not going to work although my handy dandy chart says it is doable. Might need to add some pull boxes along the way.

ETA: I would not worry at all about VD if I sized the conductors based on a NEC load calculation.

VD calculator says:

2 conductors per phase utilizing a #500 Aluminum conductor will limit the voltage drop to 2.94% or less when supplying 600.0 amps for 450 feet on a 480 volt system.
For Engineering Information Only:
310.0 Amps Rated ampacity of selected conductor
0.048 Ohms Resistance (Ohms per 1000 feet)
0.039 Ohms Reactance (Ohms per 1000 feet)
24.0 volts maximum allowable voltage drop at 5%
14.077. Actual voltage drop loss for each cable at 2.94%
28.154624441096708 volts Total maximum allowable parallel voltage drop loss for the circuit
0.9 Power Factor

 

[winnie]

Just to add to the confusion, Aluminium is frequently available in 'compact stranded' conductors, Copper rarely so.

A copper 350 kmcil XHHW has an OD of 0.8".
http://www.usawire-cable.com/pdfs/XHHW-2.pdf
In Al you would have a 500 with an OD of 0.87".
https://media.plattstatic.com/Produ...5239/0C7D3A00-35E6-4589-BF14-E1B237925239.pdf
(A Cu 500 would have an OD of 0.93")

The Al is bigger, just not as much bigger as you might expect. Make sure you use the actual cable dimensions for conduit fill calcs.

-Jon

 

[stang623]

Wow guys, great stuff here. I appreciate the sympathy on the robbery, man those guys made a killing, when we took ownership, we walked in on them that night getting ready to start their nightly shift I believe. We heard the doors as they ran out the back and found their tools and water for the evening and clothing along with a nice bundle of about 900 pounds of 500 MCM copper wire. Called the cops and gave them all the stuff for finger printing and DNA but that got us no where. Previous owner didn't even have insurance. We have since replaced all of the doors entering the building, one had been folded in half basically so you could get in if you were skinny enough. We are also occupying it and using it on a daily basis now. I also converted all the HID fixtures to LED and installed new photocells so it is really lit up bright at night...before I think 1 of the 10 lights outside worked. I think we are ok now, building sat vacant for 5 years or so before this started happening.

I did some rough estimates on the wiring I originally specified and copper was about $23,000 and the Aluminum was $8,200. I think I like the idea of the 4/0 conductors, it comes in even less, about $6,500 based on internet pricing. That would get me 574 amps at a 70% derating. I know the lights run off this panel, so I would assume the Neutral is a CCC. Then most of what we run is CNC machines and welders. From what I checked before writing this the four wires inside the cabinets are all the same size, so could I assume the Neutral is a CCC? I don't have my amp meter, its about 500 miles away at the location that was robbed. Otherwise I could at least measure this location and see what the neutral is normally doing during the day.

Based on the fact that you guys all seem to skip over it can I assume there are no special procedures for terminating aluminum wire like crimped ends or things of that sort? Maybe a chemical to prevent oxidation? These are just some of the things I read.

Thx guys.

 

[JFletcher]

Provided your sub panel has enough lugs to accept double sets of either, and use noalox on the aluminum, there really aren't any special installation procedures here. as far as the pull goes, by 4 quarts of clear Glide, then go by 20 more. you could even put a couple of quarts in the conduit, then use an air tank to blow the stuff mostly through to the other end. Reducing friction to almost nil makes pulling this a cakewalk. Having one helper with a sponge or paint brush to apply the stuff liberally as it goes in the pipe makes a world of difference. My background originally was in Telecom, where you cannot exceed 25 lb of force pulling tension. if you lube it up like I say it will practically feed itself through the pipe.

Ever been fishing and caught an eel on your line?, that's how slippery those wire should be the entire way through the conduits.

PS... If you cannot find a local electrical contractor to install aluminum for much cheaper than the copper, send me a message... LOL

 

[electrofelon]

I'm a big fan of aluminum. My advice would be to order in SimPul THHN. You can get it in colors too if you want. Thhn pulls much nicer than XHHW.

 

[JFletcher]

I'm a big fan of aluminum. My advice would be to order in SimPul THHN. You can get it in colors too if you want. Thhn pulls much nicer than XHHW.

I remember the picture you posted a while back of the colored Sim-pull you pulled going into a cabinet ... have it handy for the OP?

 

[electrofelon]

I remember the picture you posted a while back of the colored Sim-pull you pulled going into a cabinet ... have it handy for the OP?

Here are a few. The second one is 350 in 4" EMT, couple hundred feet. Not sure why the pipe was so big, I took over the job partway through. Just about had to hold that wire back it flew in so easily

The first is a mix of sizes, up to 500MCM IIRC, up to around 600 feet, 4" PVC.

I remember pulling 4X500 in 3 inch PVC with 2 90's and it wasn't a problem, although it was only me and one other guy. We pulled it with a scissor lift. Not sure off hand what the ID of 3" EMT vs PVC is.

 

[Fulthrotl]

Based on the fact that you guys all seem to skip over it can I assume there are no special procedures for terminating aluminum wire like crimped ends or things of that sort? Maybe a chemical to prevent oxidation? These are just some of the things I read.

Thx guys.

not required by code, but if you hypress on lugs to aluminum, and
prevent moisture from entering around the connection, the conductor
is as troublefree as copper.

i use burndy hypress dies, and panduit heavy walled 600 volt shrink tube.
stuff is bulletproof.

 

[infinity]

Here are a few. The second one is 350 in 4" EMT, couple hundred feet. Not sure why the pipe was so big, I took over the job partway through. Just about had to hold that wire back it flew in so easily

The first is a mix of sizes, up to 500MCM IIRC, up to around 600 feet, 4" PVC.

I remember pulling 4X500 in 3 inch PVC with 2 90's and it wasn't a problem, although it was only me and one other guy. We pulled it with a scissor lift. Not sure off hand what the ID of 3" EMT vs PVC is.

Nice work shaping in those panels. :thumbsup:

 

[electrofelon]

Nice work shaping in those panels. :thumbsup:

Thanks. That switchboard was a real pain, could have used some more room :rant:

 

[kwired]

Neutral is only carrying unbalanced current and is not considered a current carrying conductor if carrying unbalanced current of all three phases. If a majority of load is line to neutral non linear - then you have to consider the harmonic effects. This usually only an issue with something like a data center.

If your only line to neutral load is lighting and is not a majority of the load - probably not a condition to consider it current carrying neutral for ampacity adjustment purposes. Also even possible to reduce the size of the neutral conductor if it isn't carrying much load. For feeder circuits it must be no smaller then the required equipment grounding conductor in any case, otherwise can be reduced to whatever calculated load on it is (basically determine what maximum unbalance current will be).

Whether neutral is considered current carrying or not impacts adjustments enough to possibly need to increase conductor size for ungrounded conductors to achieve the desired 600 amp rating.

 

[stang623]

Some more updates on this fella's, we have been working on this building and getting it back into shape somewhat. We found some panels still functioning that had enough power to run LED lights for the entire building so we used those to get us going. At this point we would like to get one of the 600 amp panels going again...one of them is 340 ft from the switch gear. The panel is still in place in reasonable shape so we would like to keep that...only issue we have is that it had a full size neutral going to it because there was a crazy amount of light in this building as built originally, think it had 2 or 3 - 225 amp lighting panels that ran from this single 600 amp panel.

Currently there is only one lighting panel that I would like to run off of this 600 amp panel, that panel is 100 amps but the actual load if we turned everything on would be about 40 amps, is there anyway without ton's of changes that I could run a smaller neutral to the 600 amp panel so I could use 400 mcm compact stranded aluminum SIMPull wire? I have asked one person and they said I have to run a full size neutral to the 600 amp panel. My difficulty is that in the original post I thought I had 3" EMT but it is in fact parallel 2.5" RMC conduit.

Also the 400 MCM Compact stranded is a 40.7% fill with the 2.5 RMC Conduit, would this be a code fail?

 

[infinity]

Currently there is only one lighting panel that I would like to run off of this 600 amp panel, that panel is 100 amps but the actual load if we turned everything on would be about 40 amps, is there anyway without ton's of changes that I could run a smaller neutral to the 600 amp panel so I could use 400 mcm compact stranded aluminum SIMPull wire? I have asked one person and they said I have to run a full size neutral to the 600 amp panel. My difficulty is that in the original post I thought I had 3" EMT but it is in fact parallel 2.5" RMC conduit.

Also the 400 MCM Compact stranded is a 40.7% fill with the 2.5 RMC Conduit, would this be a code fail?

You can use a reduced size neutral in a feeder if you do not need the full neutral ampacity of the feeder size.

 

[ggunn]

Provided your sub panel has enough lugs to accept double sets of either, and use noalox on the aluminum, there really aren't any special installation procedures here. as far as the pull goes, by 4 quarts of clear Glide, then go by 20 more. you could even put a couple of quarts in the conduit, then use an air tank to blow the stuff mostly through to the other end.

Just don't be standing near the other end when the air starts up.

 

[kwired]

Currently there is only one lighting panel that I would like to run off of this 600 amp panel, that panel is 100 amps but the actual load if we turned everything on would be about 40 amps, is there anyway without ton's of changes that I could run a smaller neutral to the 600 amp panel so I could use 400 mcm compact stranded aluminum SIMPull wire? I have asked one person and they said I have to run a full size neutral to the 600 amp panel. My difficulty is that in the original post I thought I had 3" EMT but it is in fact parallel 2.5" RMC conduit.

Feeder neutrals only need sized per the load they will carry, but in no case can be smaller than the required EGC for that circuit. So 600 amp OCPD means 1 AWG copper or 2/0 AWG aluminum is absolute minimum neutral you can run with that feeder. I have done this before. Did this for a 600 amp feeder supplying a panelboard that served several three phase HVAC units. In addition to those units there was a 15 amp circuit supplying lighting in the vicinity, a 20 amp circuit supplying a 5-15 receptacle for servicing the units and two other 15 amp 120 volt pieces of equipment in that area. Total neutral load probably less than 30 amps - still had to run 1/0 aluminum (two in parallel because you can't parallel less than 1/0) neutral with the feeder for something that likely will never come close to loading that conductor, even if they were to add some more 120 volt loads someday down the road. Those compressor units took more than 400 amps of the 600 amp feeder otherwise I would have only ran a 400 amp feeder, so calculation wise right there we already have less than 200 amps available for potential other loads that may or may not use a neutral down the road.

Also the 400 MCM Compact stranded is a 40.7% fill with the 2.5 RMC Conduit, would this be a code fail?

I'd let it go, but I can't say what your inspector would do, it is over 40% so I guess that is justification to reject it. Perhaps if there is a possibility to further reduce neutral that can get you under 40%?