Testing

Test Setup
Testing was conducted using a standard Benfield bender and the Ericksen Bender. The force for pulling the wire through the conduit was measured for both conduit runs and the results were compared.

A conduit size of ½” emt was used because it has the smallest radius and is commonly the most difficult to pull through. Two parallel runs of conduit were tested. One with four 90° bends, bent with a Benfield bender which bends a ½” emt with a radius of 4″. The other 1/2″ emt run with four nineties was bent with the Ericksen Bender, which has a 12″ radius.

We did a test on a run with five long radius nineties. ( See Results and Conclusions )

Testing Equipment
Data acquisition system by Go-Power (GPS-2500 Series), strain gauge ( Interface B92930 ), a Greenlee 640 cable puller, nine #12 thhn-thwn solid wires, and greenlee polyline pulling twine rated at 210lbs. Two wires were bent around a loop in the twine and the other seven were taped two at a time to them. All three pulls were made this way. There was no wire lube used and the pulling twine was attached to the puller head solid with a 8/32 bolt. The wire was all cut to length, laid on a clean floor, and fed into the conduit with no pushing or pulling.

Results and Conclusion
The test performed on the conduit bent with the Ericksen Bender consistently required significantly less force to pull the wire than the conduit bent with a standard bender. The Ericksen bent conduit, on average, required 51% less force through each of the bends. In its best performing test, the Ericksen Bender outperformed the standard bender by 68%, and on its worst test, it outperformed the standard bender by 35%.

Throughout all 4 tests, the peak force required using a standard bender was 143 lbf with an average of 116 lbf through each bend.
The peak force required on Ericksen bent conduit was 74 lbf, with an average of 56.375 lbf through the bends.

The additional test of 5 bends was conducted on Ericksen bent conduit. The peak force required through the bends was 114 lbf, with an average of 76 lbf.
This test effectively demonstrated that long radius bends outperform standard bends to the point that the National Electric Code could be updated to allow additional bends, while still requiring less force than is typically required with four bends using a standard bender.

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