In what situation may a third bend in a conduit segment be acceptable without derating?

Having a third bend in a conduit segment may be acceptable without derating when one bend is located within 300 mm of the cable feed. This is because the proximity of the bend to the cable feed can reduce the effect of the bend's resistance to the cable's pull and promote better routing without excessive stress on the cables. The 300 mm distance is often used as a rule of thumb in installations to allow for an easier transition and to mitigate potential issues with cable strain or complications that arise with tighter bends further down the conduit length.

The other scenarios presented would typically lead to derating for various reasons: a run exceeding 10 meters usually requires careful consideration of derating factors; maintaining the same conduit size does not automatically account for additional bends; and evenly spaced bends, while aesthetically pleasing, do not necessarily alleviate the physical stress and electrical considerations that come with multiple turns in a conduit system. Each of these factors can impact the overall integrity of the installation and the performance of the cabling, making the specific condition regarding proximity to the cable feed particularly relevant.