Thread: Service entrance conductor strands cut.

The service entrance conductors have had some strands cut to allow the wire to fit into the clamp. I know that the clamp must be sized to the wire. This is a 125 amp service and the service conductors are 4.0 aluminum. I think that for this service rating that they could have used 2.0 copper or 1.0 aluminum. I'm calling this out but I want to know if the remaining strands are sized 1.0 for aluminum is it ever ok to do this? Thanks all!

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Good catch.... I call this out for sure. I run into it fairly often... also on larger 240V circuits (dryers, ranges, etc.). It's just wrong.... there might be a code section applies but I've never bothered to look into it.

It is incorrect to remove strands to make the conductor fit the lug. How would you determine the ampacity of the reduced conductor?

There are reducing pin lugs to accomplish the same result in a compliant manner.

I asked this question a little while ago:

http://www.inspectionnews.net/home_i...nce-cable.html

here's one of the most interesting responses:

'm not a home inspector, but I am an engineer. What has been done to this cable is quite alarming. The safe current carrying capacity of a wire is a function of its resistance, and the resistance of a material is proportional to its cross sectional area in the direction of the current flow. (In the case of braided wire, take the sum of the individual cross sectional areas for each wire.)

In other words, all things being equal, if wire A is twice the diameter of wire B, then wire A will have 4 times the current carrying capacity of wire B. This is because the cross sectional area increases as the square of the diameter. Likewise, a wire that is three times the diameter would have 9 times the current carrying capacity.

It is difficult to tell exactly, but I would estimate that the diameter of the wire in this picture has been reduced by about half along a short stretch. If this wire was rated at 100 amps for its intended voltage, then along the trimmed stretch, its safe current carrying capacity would only be a quarter, or 25 amps.