Bundling in panelboards

[mbrooke]

I know this has been asked many times here, but when you bundle conductors via a generous amount zip ties, is there any de-rating that must take place? I'm not finding anything specific.

 

[MAC702]

Good question. While I doubt there is (guessing), the fact that more heating is unavoidable is one of the many reasons I don't get involved with those "who made the prettier panel" contests. I'm sure some of you guys have been on jobsites like that.

Especially with solid wire, it stays close enough to where I want it in the panel anyway, with air around each conductor to boot.

 

[ActionDave]

I hate zip ties in panels.

 

[user 100]

I know this has been asked many times here, but when you bundle conductors via a generous amount zip ties, is there any de-rating that must take place? I'm not finding anything specific.

Not unless they are zip tied together for more than 24".....

See 310.15(B)(3)(A)

 

[mbrooke]

Good question. While I doubt there is (guessing), the fact that more heating is unavoidable is one of the many reasons I don't get involved with those "who made the prettier panel" contests. I'm sure some of you guys have been on jobsites like that.

Especially with solid wire, it stays close enough to where I want it in the panel anyway, with air around each conductor to boot.

I think we both have the same view on this. If the bundle is long enough I too can picture heat build up. Here is a perfect example. The wire is bundled together for more than 4 feet, and one set of circuits is even folded over. Starting at 1:40:


https://www.youtube.com/watch?v=CNHybxSPSXI


Technically its not so bad load wise, but I've seen 42 space commercial panels with continuous loads (lighting) exactly like that.

 

[mbrooke]

I hate zip ties in panels.

Outside of one for a MWBC, Ohhh YES! :happyyes::happyyes:

Not unless they are zip tied together for more than 24".....

See 310.15(B)(3)(A)

Thanks

 

[user 100]

I hate zip ties in panels.

X3

Some guys think that it makes a job look more professional or neater.

Nothing neat or professional about wasting time to squeeze wires together.:happyno:

 

[Cow]

I've never been hassled about bundling in a panel, and if that were the case, 310.15(A)2 Exception would most likely get me out of it.

 

[mbrooke]

Not unless they are zip tied together for more than 24".....

See 310.15(B)(3)(A)

For the record:

(3) Adjustment Factors.

(a) More Than Three Current-Carrying Conductors.
Where the number of current-carrying conductors in a raceway
or cable exceeds three, or where single conductors or
multiconductor cables are installed without maintaining spacing
for a continuous length longer than 600 mm (24 in.) and
are not installed in raceways, the allowable ampacity of each
conductor shall be reduced as shown in Table 310.15(B)(3)(a).
Each current-carrying conductor of a paralleled set of conductors
shall be counted as a current-carrying conductor.

 

[mbrooke]

I've never been hassled about bundling in a panel, and if that were the case, 310.15(A)2 Exception would most likely get me out of it.

Ok- I'm confused. How would that apply :?

(2) Selection of Ampacity. Where more than one ampacity
applies for a given circuit length, the lowest value shall be
used.
Exception: Where two different ampacities apply to adjacent
portions of a circuit, the higher ampacity shall be
permitted to be used beyond the point of transition, a distance
equal to 3.0 m (10 ft) or 10 percent of the circuit
length figured at the higher ampacity, whichever is less.
Informational Note: See 110.14(C) for conductor temperature
limitations due to termination provisions.

 

[user 100]

Ok- I'm confused. How would that apply :?

Ok, bear w/me. Heres an explanation of what this exception is saying....

Say you have a ckt with 2 sections with different ampacities due to derating-SEC1 and SEC2.

SEC1 is 60' long and is fused at the full ampacity.
SEC2 is 4' long and has been subject to derating (lower ampacity).

Now, 10% of SEC2 is 4', which is less than 10' and is also less than 10% (or 6ft) of the figured ckt length of SEC1.

What this means is than since the values of the derated part of the ckt (SEC2) are less than 10' or 10% (and as the art says whichever of those values are less) of the non derated part (SEC1), the full ampacity (the ampacity of SEC1), can be used for the ENTIRE ckt.

IOWS, Cow doesn't have to derate anything when it comes to "bundling" in a panel- the exception gives him an out.


ETA: Hopefully that was simple enough- Smart$ and Charlie B have both posted much better explanations about this before, maybe one of them will see this.

 

[user 100]

Ok, bear w/me. Heres an explanation of what this exception is saying....

Say you have a ckt with 2 sections with different ampacities due to derating-SEC1 and SEC2.

SEC1 is 60' long and is fused at the full ampacity.
SEC2 is 4' long and has been subject to derating (lower ampacity).

Now, 10% of SEC2 is 4', which is less than 10' and is also less than 10% (or 6ft) of the figured ckt length of SEC1.

What this means is than since the values of the derated part of the ckt (SEC2) are less than 10' or 10% (and as the art says whichever of those values are less) of the non derated part (SEC1), the full ampacity (the ampacity of SEC1), can be used for the ENTIRE ckt.

IOWS, Cow doesn't have to derate anything when it comes to "bundling" in a panel- the exception gives him an out.


ETA: Hopefully that was simple enough- Smart$ and Charlie B have both posted much better explanations about this before, maybe one of them will see this.

^^^^^^^^^^^
This explanation was for the 2014.

For those on the 2017, theres been a little change and there is a need for clarification:

You will now need to find out if the section of the ckt w/ a lower ampacity exceeds 10ft or 10% of the length of the ckt in its entirety (you no longer worry about the length of section with higher ampacity) in order for 310.15(A)(2) to kick in.

 

[mbrooke]

Ok, bear w/me. Heres an explanation of what this exception is saying....

Say you have a ckt with 2 sections with different ampacities due to derating-SEC1 and SEC2.

SEC1 is 60' long and is fused at the full ampacity.
SEC2 is 4' long and has been subject to derating (lower ampacity).

Now, 10% of SEC2 is 4', which is less than 10' and is also less than 10% (or 6ft) of the figured ckt length of SEC1.

What this means is than since the values of the derated part of the ckt (SEC2) are less than 10' or 10% (and as the art says whichever of those values are less) of the non derated part (SEC1), the full ampacity (the ampacity of SEC1), can be used for the ENTIRE ckt.

IOWS, Cow doesn't have to derate anything when it comes to "bundling" in a panel- the exception gives him an out.


ETA: Hopefully that was simple enough- Smart$ and Charlie B have both posted much better explanations about this before, maybe one of them will see this.

Ok- I think I get this (for now)- but can you give a real world scenario or example of this would apply?

 

[Smart $]

...
ETA: Hopefully that was simple enough- Smart$ and Charlie B have both posted much better explanations about this before, maybe one of them will see this.

I see it. Now what?

Ok- I think I get this (for now)- but can you give a real world scenario or example of this would apply?

Before we go that far, note that the 'bundling' requirement only concerns wires in a raceway or cable. There is no such requirement for bundling inside enclosures. Yes, the physics are quite similar, though panelboards typically provide more space about the conductors than does raceway or cable. However, I do believe bundling en masse should be addressed regardless of Code lacking any restriction or ampacity adjustment.

That said, the concept underlying 310.15(A)(2) Exception does provide some level of compensation for panelboard conductor bundling.

 

[mbrooke]

I see it. Now what?


Before we go that far, note that the 'bundling' requirement only concerns wires in a raceway or cable. There is no such requirement for bundling inside enclosures. Yes, the physics are quite similar, though panelboards typically provide more space about the conductors than does raceway or cable. However, I do believe bundling en masse should be addressed regardless of Code lacking any restriction or ampacity adjustment.

That said, the concept underlying 310.15(A)(2) Exception does provide some level of compensation for panelboard conductor bundling.

But how much compensation? I am still skeptical of 310.15 (A) (2) for panel boards on how it would apply.

 

[infinity]

I've never been hassled about bundling in a panel, and if that were the case, 310.15(A)2 Exception would most likely get me out of it.

If the bundling compensation does apply to cable ties in panelboards then would take care of it in most situations so it becomes a non-issue and the point is moot.

 

[kwired]

But how much compensation? I am still skeptical of 310.15 (A) (2) for panel boards on how it would apply.

You can bundle said conductors as they pass through panelboard cabinet then nipple into and run same conductors through aux gutters as long as you don't exceed 30 CCC in the gutter (without requiring ampacity adjustments).

 

[ptonsparky]

I hate zip ties in panels.

They cut easily.

 

[K8MHZ]

They cut easily.

And make you bleed, too.

 

[jumper]

I hate zip ties in panels.

Then you would really cuss me out if you ever follow behind me in a control panel.