Getting #250 Al onto 1/0 Lugs

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StevenLeuck

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Eugene, OR, USA
We have a large multi-family mixed use building we are just now bringing out of the ground. We're trying to figure out a solution to the over-sized conductors on too-small lugs. All of our residential units require only a 100Amp loadcenter. We've solved the connection at that end of the feeder by buying 150A rated MLO loadcenters which have lugs good for up to 300KcMIL. However, it's the other end that has me concerned. The meter/main meter packs we're using are Eaton (Cutler-Hammer) and the 2-pole mains will be BR2100 circuit breakers. Submittal sheets say the maximum wire size on their lugs is 1/0. However, due to distances, we have about half the building requiring #2/0 feeders, plus a small handful of them at both #4/0 and #250KcMIL. I've been researching ways to reduce the conductor size to fit on the 1/0 lugs but not finding anything conclusive. Am curious to know what others have done as inevitably, there are others who have run into this before us. I can't find any manufacturers who make a compression reducer that will go from 250 to 1/0. Mechanical lugs are plentiful for this. I'm hoping I can find out from others what they've done in the past. Also curious about code quotation to back us up with the inspector for having 10' of 1/0 AL at the beginning of a #250 AL feeder in case they have a problem with it.
 
There is no code quotation to back up your plan because the code is permissive. It does not list exhaustively all the things that are allowed.

You are using larger conductors to limit voltage drop. Do the voltage drop calculation adding 10' of smaller, but code approved, wire at the end and notice that the difference is negligible.
Doing what you suggest is a separate junction box will also avoid any bending space problems with the larger wire.
 
GoldDigger said:
There is no code quotation to back up your plan because the code is permissive. It does not list exhaustively all the things that are allowed.

You are using larger conductors to limit voltage drop. Do the voltage drop calculation adding 10' of smaller, but code approved, wire at the end and notice that the difference is negligible.
Doing what you suggest is a separate junction box will also avoid any bending space problems with the larger wire.
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Thank you! My thinking was inline with what you suggested... the voltage drop difference will be negligible and easily demonstrated for the inspector (a former employee!!). Was hoping I wasn't missing anything and appreciate the comment. We had already determined to have an oversized wireway above the meter paks and will most likely do the reducing splices there.

Thank you.
 
StevenLeuck said:
We have a large multi-family mixed use building we are just now bringing out of the ground. We're trying to figure out a solution to the over-sized conductors on too-small lugs. All of our residential units require only a 100Amp loadcenter. We've solved the connection at that end of the feeder by buying 150A rated MLO loadcenters which have lugs good for up to 300KcMIL. However, it's the other end that has me concerned. The meter/main meter packs we're using are Eaton (Cutler-Hammer) and the 2-pole mains will be BR2100 circuit breakers. Submittal sheets say the maximum wire size on their lugs is 1/0. However, due to distances, we have about half the building requiring #2/0 feeders, plus a small handful of them at both #4/0 and #250KcMIL. I've been researching ways to reduce the conductor size to fit on the 1/0 lugs but not finding anything conclusive. Am curious to know what others have done as inevitably, there are others who have run into this before us. I can't find any manufacturers who make a compression reducer that will go from 250 to 1/0. Mechanical lugs are plentiful for this. I'm hoping I can find out from others what they've done in the past. Also curious about code quotation to back us up with the inspector for having 10' of 1/0 AL at the beginning of a #250 AL feeder in case they have a problem with it.
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Use a Polaris connector that goes from the 4/0-250MCM to a smaller jumper wire that will fit the 1/0 lugs:

http://www.polarisconnectors.com/pdfs/nsi/it_series.pdf

Using a few feet of 1/0 from that connector in a gutter below/above the meter will not affect voltage drop but a fraction of a %.

eta: as far as code issues, as long as the 1/0 is suitable for the calculated ampacity and OCPD, you will be fine. A few might want torque values or % fill of your gutter/panel/can housing.

seta: If you're on a 150A breaker, you'll have to use 1/0 in copper only; AL is good for just 120A.
 
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Also, you realize that if you use Polaris connectors on both ends and 90*C wire, you are permitted to use the 90*C table for ampacity for the wire between the 2 (but 75*C for the wire from connector to meter and breaker). I know you oversized for VD reasons, just throwing that out there.
 
StevenLeuck said:
We have a large multi-family mixed use building we are just now bringing out of the ground. We're trying to figure out a solution to the over-sized conductors on too-small lugs. All of our residential units require only a 100Amp loadcenter. We've solved the connection at that end of the feeder by buying 150A rated MLO loadcenters which have lugs good for up to 300KcMIL. However, it's the other end that has me concerned. The meter/main meter packs we're using are Eaton (Cutler-Hammer) and the 2-pole mains will be BR2100 circuit breakers. Submittal sheets say the maximum wire size on their lugs is 1/0. However, due to distances, we have about half the building requiring #2/0 feeders, plus a small handful of them at both #4/0 and #250KcMIL. I've been researching ways to reduce the conductor size to fit on the 1/0 lugs but not finding anything conclusive. Am curious to know what others have done as inevitably, there are others who have run into this before us. I can't find any manufacturers who make a compression reducer that will go from 250 to 1/0. Mechanical lugs are plentiful for this. I'm hoping I can find out from others what they've done in the past. Also curious about code quotation to back us up with the inspector for having 10' of 1/0 AL at the beginning of a #250 AL feeder in case they have a problem with it.
Click to expand...

you can buy finger lugs that hypress onto aluminum wire, and have a smaller extrusion to fit under the lug. the good thing is that they provide a permanant connection for aluminum that does not deteriorate over time, nor loosen. they are the only way i will land aluminum conductors onto a breaker. it leads to a connection as good as copper.

in severely corrosive situations, you can use panduit heat shrink that will give you a permanant waterproof connection. works in a salt air environment.
 
Reducing wire size is common when you're using much larger conductors for voltage drop. Here's several hundred feet of parallel conductors for a 200 amp ATS.

20130206_100136.jpg
 
Fulthrotl said:
you can buy finger lugs that hypress onto aluminum wire, and have a smaller extrusion to fit under the lug. the good thing is that they provide a permanant connection for aluminum that does not deteriorate over time, nor loosen. they are the only way i will land aluminum conductors onto a breaker. it leads to a connection as good as copper.

in severely corrosive situations, you can use panduit heat shrink that will give you a permanant waterproof connection. works in a salt air environment.
Click to expand...
One problem he likely runs into though is that there is not enough bending space for a 250 conductor in a meter center compartment that is only rated for 100-125 amps.
 
JFletcher said:
seta: If you're on a 150A breaker, you'll have to use 1/0 in copper only; AL is good for just 120A.
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My understanding is there is 150 amp main lug panel (which will accept his 250 conductors), but the feeder breaker is only a 100 amp breaker and only accepts up to 2/0 conductor. The conductor is larger for voltage drop reasons and not ampacity reasons. Is also likely there isn't appropriate bending space on the supply end even with a reducing device that attaches directly to the conductor.
 
Wouldn't want to show this to someone and simply say "hook it up just like the picture shows". :)


JAP>
 
petersonra said:
Do the bending space rules apply to the install or to the product?
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Kind of sort of both IMO.

100/125 amp meter sockets, circuit breaker enclosures typically only have lugs that accept about 2/0 maximum conductor as well as have bending space not much more then is needed for 2/0 conductor. 200/225 amp devices often accept about 300 kcmil max conductor and have no more bending space then is needed for 300 also.
 
75 degree conductors vs 90 degree.

75 degree conductors vs 90 degree.

JFletcher said:
Also, you realize that if you use Polaris connectors on both ends and 90*C wire, you are permitted to use the 90*C table for ampacity for the wire between the 2 (but 75*C for the wire from connector to meter and breaker). I know you oversized for VD reasons, just throwing that out there.
Click to expand...

Can you provide a little more information about this? I don't understand the difference between the ampacity of the long wires and the short wires.
 
Greg1707 said:
Can you provide a little more information about this? I don't understand the difference between the ampacity of the long wires and the short wires.
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It's not about the wire.
It's about the temperature rating of the terminals.

Most Polaris connector terminals are rated at 90d C so you can use the 90d C column when determining the amperage of the long wires in between 2 Polaris connectors.

Breakers or meters generally have lugs only rated at 75d C so the short wire from the Polaris connector to the meter or the short wire from the Polaris conductor to the breaker terminals needs to be figured in the 75d column.

At least that's what I think he's trying to say.

JAP>
 
jap said:
It's not about the wire.
It's about the temperature rating of the terminals.

Most Polaris connector terminals are rated at 90d C so you can use the 90d C column when determining the amperage of the long wires in between 2 Polaris connectors.

Breakers or meters generally have lugs only rated at 75d C so the short wire from the Polaris connector to the meter or the short wire from the Polaris conductor to the breaker terminals needs to be figured in the 75d column.

At least that's what I think he's trying to say.

JAP>
Click to expand...

Exactly what I was getting at. And if you happen to need a feeder with an ampacity right on the edge of wire sizes, like 425A, it's the difference between using 500MCM copper (430A @ 90*C) and 750 MCM copper (475A @ 75*C - 600 is good to 420A). or parallel sets of 3/0 vs 4/0. On a long run, that will add up quickly, especially if you also have to upsize the conduit to hold the larger wires rated at 75*C vs 90*C.
 
JFletcher said:
Exactly what I was getting at. And if you happen to need a feeder with an ampacity right on the edge of wire sizes, like 425A, it's the difference between using 500MCM copper (430A @ 90*C) and 750 MCM copper (475A @ 75*C - 600 is good to 420A). or parallel sets of 3/0 vs 4/0. On a long run, that will add up quickly, especially if you also have to upsize the conduit to hold the larger wires rated at 75*C vs 90*C.
Click to expand...

That's good thinking.

JAP>
 
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