[code4me]

Is it per code to run non direct burial aluminum cable in a PVC conduit underground. I thought I had read where since aluminum wiring heats up more than copper it could cause problems. I am going to run 150 feet of conduit.. Tks Jack Schmieder

[ohb0b]

Is it per code to run non direct burial aluminum cable in a PVC conduit underground. I thought I had read where since aluminum wiring heats up more than copper it could cause problems. I am going to run 150 feet of conduit.. Tks Jack Schmieder

Yes, as long as you do not exceed the conduit fill limitations, the conductors are rated for wet locations, and the burial depth is in accordance with the tables in article 300.


As for heat:

-the heat problems associated with using aluminum wire have to do with different coefficients of expansion between aluminum and copper, causing connections between aluminum wire and copper terminals to work loose. Make sure your connections are approved for aluminum wire. It has nothing to do with resistance heating along the wire's length.
-While it is true that aluminum has a greater resistivity than copper, which makes it heat up more, this is compensated for by requiring a larger size wire for the same amount of current. As long as you install using the tables in article 310, you will not overheat the conductor. You may also want to do a voltage drop calculation to make sure the wire is large enough.
-heat is also a minor consideration in buried cable. Soil (particularly wet soil) is a very good conductor of heat, and what would you burn underground anyway?

[code4me]

Thanks ohbob. That answers my question... Jack