Aluminum and Copper

[KasseemF]

What does the code say for the following scenario is it acceptable or no?

I have Aluminum 500MCM single phase ( 2 lives , 1 neutral) from my supliers transformer to my main panel to a 400A disconneect, then 1/0AWG and 2/0AWG copper wires to sub-panels from all my subpanels and copper grounding.

I just want to know if mixing of aluminum and copper in a system in this way.

 

[480sparky]

As long as they are 1. sized to carry the load impressed on them, 2. protected according to 310.15 and 3. installed correctly, there's no problems I can think of.

It's common to have aluminim service conductors, and copper branch circuits.

 

[raider1]

I agree with Ken.

It is very common for services to have aluminum conductors and copper within the building.

Chris

 

[slick 50]

What does the code say for the following scenario is it acceptable or no?

I have Aluminum 500MCM single phase ( 2 lives , 1 neutral) from my supliers transformer to my main panel to a 400A disconneect, then 1/0AWG and 2/0AWG copper wires to sub-panels from all my subpanels and copper grounding.

I just want to know if mixing of aluminum and copper in a system in this way.

What size fuses do you have in the 400 amp disconnect? 500 mcm Aluminum is only good to 310 amps at 75 degree F. You must have it fused according to feeders.

 

[benaround]

What size fuses do you have in the 400 amp disconnect? 500 mcm Aluminum is only good to 310 amps at 75 degree F. You must have it fused according to feeders.

If residential service 500MCM AL. is good for 350amps. Table 310.15 b 6

 

[slick 50]

If residential service 500MCM AL. is good for 350amps. Table 310.15 b 6

I see where you are coming from here. As long as the lugs on the OCPD are rated for 90 degree C you can go 350 amp but most lugs are rated at 75 degree which means you would have to derate the conductor.

 

[augie47]

What does the code say............

110.14 Electrical Connections.
Because of different characteristics of dissimilar metals, devices such as pressure terminal or pressure splicing connectors and soldering lugs shall be identified for the material of the conductor and shall be properly installed and used. Conductors of dissimilar metals shall not be intermixed in a terminal or splicing connector where physical contact occurs between dissimilar conductors (such as copper and aluminum, copper and copper-clad aluminum, or aluminum and copper-clad aluminum), unless the device is identified for the purpose and conditions of use. Materials such as solder, fluxes, inhibitors, and compounds, where employed, shall be suitable for the use and shall be of a type that will not adversely affect the conductors, installation, or equipment.

 

[benaround]

I see where you are coming from here. As long as the lugs on the OCPD are rated for 90 degree C you can go 350 amp but most lugs are rated at 75 degree which means you would have to derate the conductor.

Slick, I don't think you looked at Table 310.15(B)(6), it has nothing to do with 90deg

ratings, It is for 120/240v 3wire single phase dwelling services, and 500MCM AL. is good

for 350 amps.

 

[peter d]

I agree with Ken.

It is very common for services to have aluminum conductors and copper within the building.

Chris

According to one of Southwire's online tutorials, 90% of service entrance conductors in the USA are aluminum.

 

[raider1]

According to one of Southwire's online tutorials, 90% of service entrance conductors in the USA are aluminum.

That doesn't surprise me. That is about what I see when I inspect services.

Chris

 

[don_resqcapt19]

I see where you are coming from here. As long as the lugs on the OCPD are rated for 90 degree C you can go 350 amp but most lugs are rated at 75 degree which means you would have to derate the conductor.

Even if the lugs on the breaker were rated for 90?C you still couldn't use the 90?C ampacity because the breaker itself will not be rated for use with 90?C conductors. (as someone has already pointed out, the permission to use the conductor at 350 amps for a residential service has nothing to do with the 90?C rating)

 

[hillbilly1]

110.14 Electrical Connections.
Because of different characteristics of dissimilar metals, devices such as pressure terminal or pressure splicing connectors and soldering lugs shall be identified for the material of the conductor and shall be properly installed and used. Conductors of dissimilar metals shall not be intermixed in a terminal or splicing connector where physical contact occurs between dissimilar conductors (such as copper and aluminum, copper and copper-clad aluminum, or aluminum and copper-clad aluminum), unless the device is identified for the purpose and conditions of use. Materials such as solder, fluxes, inhibitors, and compounds, where employed, shall be suitable for the use and shall be of a type that will not adversely affect the conductors, installation, or equipment.

I think the OP is refering to aluminum on the line side of the meterbase, with the load side being copper, Although your quote is a good reminder for those that don't know that copper and aluminum are not be combined without proper seperation. I came behind a technical college professor that taught electrical had installed a #10 Cu type uf cable together with a 4/0 AL USE cable, after about 4 years the cable corroded, and the well pump quit.