Cables in concrete trench

[winslowfam]

Hi...we would like to use an existing concrete trench for installing feeder cables. This trench is old and was installed to carry cables years ago. One electrician has raised a question about whether or not this is allowed now, because of possible damage to cables because of seepage from the concrete (lime?). Is there such a code issue with cables in direct contact with concrete? Thanks.

 

[ron]

Often feeders are encased in concrete. I wouldn't worry about lime. Be sure you use an appropriate raceway for exposed applications.

 

[winslowfam]

the feeders will be cables rather than in conduit...does that change your thoughts?

 

[ceb58]

Hi...we would like to use an existing concrete trench for installing feeder cables. This trench is old and was installed to carry cables years ago. One electrician has raised a question about whether or not this is allowed now, because of possible damage to cables because of seepage from the concrete (lime?). Is there such a code issue with cables in direct contact with concrete? Thanks.

One could agree about the damage using 110.11.

 

[winslowfam]

one other thing...the cables will only be laying in the bottom of this concrete trench, not imbedded in concrete...seems that it would be fine, but would like to hear if we are missing something. Thx.

 

[ron]

Can you give us an example of the type of cable/jacket? Is the trench protected by anything above? As mentioned, you need to think about exposure to damage.

 

[don_resqcapt19]

It was common to use a concrete trench with covers as cable tray in many older industrial applications. Not sure it was ever code compliant, but I don't see a lot of difference between laying the cables in a concrete trench as compared to laying them in solid bottom tray. Sometimes strut or other supports were installed in the bottom of the trench and the cables were attached with some type of clamp. You had to make sure the clamp was non-ferrous or non-continuous around the cables if they were single conductors.