# wire bending radius



## ICE

Shirley there must be a code section for the bending radius of wire.  I wrote a correction that asked for a four inch radius.  An inspector has challenged me to provide a code section.  I don't have a picture of the wire but it must have been too tight so I wrote the correction.

Today I encountered the same violation and that's the pictures here.  As you can see there is damage to the insulation.  What you can't see is possible damage to the insulation on the other side of the bend.  If there is damage there, it is against the metal enclosure.  So I can write a correction for the damaged insulation but what about the bending radius.  I can bend that size wire just as tight without damage to the insulation.

Section 300.34 is the only place that I have found with a code for wire bending radius but that section applies to over 1000 volts.  What I am dealing with is 2/0 wire in service panel enclosures.

The radius here is that of a nickle.

If there is no code it must not be a problem, which suits me just as well.


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## Gregg Harris

Should be in 306.34 330.24 NEC


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## ICE

Gregg Harris said:


> Should be in 306.34 330.24 NEC


I don't have a 306.34 and 330.24 is for MC cable.


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## Gregg Harris

I was guessing at the section Ice I am positive it is in section 300 but do not have a book with me. Try 300.34/ 336 334. 24 the charts are there


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## Gregg Harris

8 times the overall cable diameter


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## cda

Maybe?:


http://www.electricallicenserenewal...ation-Courses/NEC-Content.php?sectionID=280.0


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## cda

Manufacture requirements?


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## cda

Sorry no year reference


Bending Radius
Care should be taken not to exceed the bending radius of the cables when routing around corners. According to NEC Article 320.24, for AC cable, the radius of the curve of the inner edge of any bend shall not be less than 5 times the diameter of the cable. NEC Article 330.24(B) states that for MC Cable, the radius shall not be less than 7 times the external diameter of the cable.


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## ICE

Gregg Harris said:


> 8 times the overall cable diameter


That’s 300.34 and only over 1000 volts.


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## ICE

cda said:


> Sorry no year reference
> 
> 
> Bending Radius
> Care should be taken not to exceed the bending radius of the cables when routing around corners. According to NEC Article 320.24, for AC cable, the radius of the curve of the inner edge of any bend shall not be less than 5 times the diameter of the cable. NEC Article 330.24(B) states that for MC Cable, the radius shall not be less than 7 times the external diameter of the cable.


But what about a single wire?


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## ICE

cda said:


> Manufacture requirements?


I hadn’t thought about that.  Perhaps Southwire has an opinion.


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## ICE

cda said:


> Maybe?:
> 
> 
> http://www.electricallicenserenewal...ation-Courses/NEC-Content.php?sectionID=280.0


Nope....that’s the minimum space allowed for the wire.


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## Francis Vineyard

312.6 

FWIW 2017 110.14 have fun with the new text that enforces the installers to use a torque wrench!


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## linnrg

conduit bodies have depths and dimensions based upon conductor sizing.  What size LB would you need for that conductor? That is basically a 90 degree turn


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## linnrg

table 312.6A


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## ICE

Apparently there is no code for the bending radius of individual wires. There are codes for the space provided for bent wire as well as the bending radius of cable but nothing for conductors unless the voltage exceeds 1000 volts.

Live and learn.


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## mark handler

http://cooperenergysolutions.com/co...-type_metering/ed-minimumwirebendingspace.pdf
Minimum wire bending space at terminal
NEC Table 312.6(A)
NEC Table 312.6(B)


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## ICE

Mark,
That is the space that the wire occupies.  Looking at the pictures there is plenty of space but the wire is not obligated to utilize all of that space.

_312.6 Deflection of Conductors. 
Conductors at terminals or conductors entering or leaving cabinets or cutout boxes and the like shall comply with 312.6(A) through (C). 
(B) Wire-Bending Space at Terminals. Wire-bending space at each terminal shall be provided in accordance with 312.6(B)(1) or (B)(2). 

(1) Conductors Not Entering or Leaving Opposite Wall. 

Table 312.6(A) shall apply where the conductor does not enter or leave the enclosure through the wall opposite its terminal. 
_
The conductor does not enter or leave the enclosure through the wall opposite its terminal.  Therefor there shall be a clear space no less than 3.5" in front of the terminal. That in no way dictates a minimum bending radius for the conductor.  Clearly there can be a situation where the maximum radius is limited to that which will fit within a 3.5" clear space in front of a terminal.

This next picture is aluminum wire.  I asked for a larger bending radius.  I was wrong.  I have been getting it wrong for a long time.  That's great news as now I will get it right.....for a much shorter time.





Go ahead, beat it with a hammer, just make sure it's a Finish hammer.


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## ICE

The code provides a chart that defines the minimum space allowed in front of a terminal but there is no indication of a minimum width of that space or the radius of bends.  The result of that is the work found in these pictures.

Here is a picture that I posted recently on this topic.  Nobody contradicted me at that time.  I suppose common sense took hold.  Well then Shirley, common sense has led me down the wrong path. It's a simple process to revise Tiger code.....no committees.....it passes like corn through a duck.


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## Francis Vineyard

Gregg Harris said:


> 8 times the overall cable diameter


Guess it depends on the edition, mine says 5 times.


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## Francis Vineyard

ICE said:


> I hadn’t thought about that.  Perhaps Southwire has an opinion.


They may further clarify if damage when the insulation is folded or wrinkle on the inside radius and therefore may stretch on the opposite side.


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## ICE

Francis Vineyard said:


> Guess it depends on the edition, mine says 5 times.


Where will I find that?


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## ICE

Francis Vineyard said:


> They may further clarify if damage when the insulation is folded or winkle on the inside radius and therefore may stretch on the opposite side.


I called Southwire several times today and did not get an answer.


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## Mark K

The insulation damage in the original photo is not because of bending the wire.  Rather it is because of the tool used to bend the wire.


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## Francis Vineyard

ICE said:


> Where will I find that?


334.34


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## Francis Vineyard

ICE said:


> I called Southwire several times today and did not get an answer.


Can get you a contact next week when I return to work.


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## Francis Vineyard

Mark K said:


> The insulation damage in the original photo is not because of bending the wire.  Rather it is because of the tool used to bend the wire.


I'm seeing what appears to be rippling of the insulation on the opposite side of the punctures . . .
ICE could explain what it is


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## ICE

Francis Vineyard said:


> Can get you a contact next week when I return to work.


I would appreciate that.


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## ICE

The insulation is puckers on one side and torn on the other.  I suspect that pliers was used to complete the bend and that tore the insulation.


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## ICE

Francis Vineyard said:


> 334.34


There is no 334.34 in the California Electrical Code.


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## Francis Vineyard

ICE said:


> There is no 334.34 in the California Electrical Code.


334.24


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## Francis Vineyard

ICE said:


> The insulation is puckers on one side and torn on the other.  I suspect that pliers was used to complete the bend and that tore the insulation.


Did the bend make it pucker?


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## ICE

Francis Vineyard said:


> 334.24


That is for cable.


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## Francis Vineyard

ICE said:


> That is for cable.


True and so is 338, but you did ask about wire.


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## ICE

Francis Vineyard said:


> True and so is 338, but you did ask about wire.


And I appreciate your interest. I am stuck with finding a code for individual conductors.


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## Mark K

Suggest that the puckering is a non-issue.  There is just more air between the surface of the insulation and the wire which if anything provides more, although inconsequential, protection against a shock.


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## cda

ICE said:


> And I appreciate your interest. I am stuck with finding a code for individual conductors.




Do you happen to have the brand


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## ICE

cda said:


> Do you happen to have the brand


No.  I found this at an inspection of PV.  The panel is new and bootlegged.  There’s plenty wrong with it and I will be seeing it again.  It is never easy to find labels on wire but I’ll try.


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## chris kennedy

ICE said:


> I hadn’t thought about that.  Perhaps Southwire has an opinion.


All Southwire has to say is don't damage the cable.
See 3.1.4 in this link.


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## cda

So sounds like the code allows it to be tied in knots??


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## Mark K

The wires in the boxes with outlets are often bent with very tight radiuses and yet we apparently have no problem?


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## ICE

I have found little on the subject.  There are manufactures showing up in a Google search.  If I understand the literature, some ask for 4 to 5 times the width. I have seen 8 mentioned.  Southwire asks for no damage. However I have no way to know which to take seriously.  There is a valid question of what is too tight for a 2/0 conductor.  Exactly what is the damage?  Is it damage to the insulation or the metal?  When does damage ensue?  Is the damage obscured by the insulation? 

Other forums declare this to be nonsense and not worthy of consideration.  There simply can't be a too small bend in a conductor.  As long as the wire is not separated it is code compliant.  

The code is silent until 1000 volts is exceeded.  I wonder what the UL Standard for the wire has to say.  Does the Listing for the wire include installation instructions?  And if so, what do the instructions contain?  

12AWG wire can be bent around a screw and still maintain a proper radius.  Consider the physical difference between a #12 and a 2/0.   Using them in a comparison is not valid.


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## cda

Mike holt where are you


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## north star

*$ >*



> *" Exactly what is the damage? Is it damage to the insulation or the metal?*
> * When does damage ensue ? "*


The damage occurs when the radius of the metal  inside the sheathing
is reduced to no longer be able to carry the intended amperage  [  i.e. - the
metal strands are overstretched beyond what they were designed  ]......
The multiple stands are rated "together" as one assembly, to carry the
intended load.

*< $*


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## Mark K

Stretching of the strands is not a problem unless they break.  Only then is the wire damaged.  I would suggest that the insulation is not a problem unless it is broken in which case some electricians tape should solve the problem.

On the other hand if you don't agree then write up every house.


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## Francis Vineyard

ICE said:


> And I appreciate your interest. I am stuck with finding a code for individual conductors.


Send me an email if you want his phone number: http://abernathypaul.wixsite.com/masterthenec/founder


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## steveray

It seems like a lot of manufacturers are leaving themselves a lot of wiggle room these days...In order to sell more product or make their customers happy and someone else left holding the bag....I have had a similar dialogue with Paul for installing MC or NM cable before a building is dried in where the manufacturer says "as long as it is not saturated it will be fine", but who is going to be on the hook for determining that...He is a good, smart guy, especially when he agrees with me....


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## steveray

The note at the bottom of Table 312.6A says that the clear space  is measured in the direction that the cable leaves the terminal, to the wall barrier or obstruction, I think that gives you the ability to cite most of your pics....


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