Article 300.34

[jbolen]

I must be getting old....but I do not understand art 300.34...bending radius of 1/0 wire or less.

My 40 years at this game whne could always bend it 90*......I have an Army Corp of Eng. saying you can not bend 90*.

Please justify

 

[augie47]

note that 300.34 apples to conductors operating at over 600 volts.
The end result of the bend may still be 90?, but sharp bend (small radius) can cause damages to conductors, especially ones rated at >600 volts.
On higher voltage cables the sharp bends can effect the shielding and cause corona problems.

 

[nakulak]

bending radius is always a factor that should be considered, even when it doesn't apply. 300.34 only applies to conductors and cables over 600 volts. if you are using conductors and cables under 600, then other articles apply, but 300.34 is a general rule of thumb for most conductors or cables (in my opinion). for example, 336.24 gives the bending radius of tray cable. 312.6 and 430.10 give minimum wire bending space at terminals to prevent overcrowding and overbending of conductors at these locations. Cable and wire manufacturers also sometimes include minimum bending radius in their specs for wire and cable. I got in trouble once on a gov job for overbending explosionproof flexes (an expensive item to replace) cause the engineer took a ruler to them. If you are not using voltages over 600, though, 300.34 does not apply.

 

[Chamuit]

Have you ever looked inside some all-in-one panels? Manufacturers bend some of their wires into hard 90s.

 

[nakulak]

yes, but those are usually listed with the wiring complete.