Are the cables correctly supported in the picture below?

[zemingduan]

Do you see any issue with the installation in the below picture? Are the cables correctly supported only by one bracket? I think the space may not maintained between the cables. Derate of the conductors need to be considered?

 

[Dennis Alwon]

How long is the run? Are these line voltage or low voltage cables?

 

[zemingduan]

How long is the run? Are these line voltage or low voltage cables?

These are line voltage 125A apartment feeders running from the apartment distribution panel to each electrical panel inside the apartment unit. The whole run is probably 100'+. This is a portion of the run!

 

[infinity]

Bundling is not defined by the NEC so if the inspector thinks that it's okay it's good enough for me.

 

[Buck Parrish]

I've had inspectors in Durham NC tell me to split them up. No more bundling like we used to do. Since then we space them evenly so as not to get into any derating issues.
I should've asked for a code section.
I know they're sections for derating multiple wires in conduit or undeground or through holes.

 

[Dennis Alwon]

As Trevor stated there is no clear definition of bundling. For instance, how much space is required between cables to not be bundled? The case of bundling may be an authority having jurisdiction call. In this case I would probably consider it bundling but as you see there are places where the cables do have space between them.

 

[Dennis Alwon]

The issue would be the of the cable being secured and supported would be subjective also. Certainly these cables are supported but are they secured? Imo, it is not an issue assuming the strapping is within the legal spacing.

 

[infinity]

As Trevor stated there is no clear definition of bundling. For instance, how much space is required between cables to not be bundled? The case of bundling may be an authority having jurisdiction call. In this case I would probably consider it bundling but as you see there are places where the cables do have space between them.

Ask 100 people and more people would say that they're bundled than those who said they're not bundled but ultimately it's the inspector's call. Given the small air gaps around each cable it's not likely that there will be an issue with overheating.

 

[david]

Do you see any issue with the installation in the below picture? Are the cables correctly supported only by one bracket? I think the space may not maintained between the cables. Derate of the conductors need to be considered?

I doubt the calculated load is a 100 amps, if it was called out for bundling change the feeder breaker to a smaller size. I wouldn't call it bundling just don't add zip ties between strapping thinking you want it to look neater

 

[Dennis Alwon]

I doubt the calculated load is a 100 amps, if it was called out for bundling change the feeder breaker to a smaller size. I wouldn't call it bundling just don't add zip ties between strapping thinking you want it to look neater

Not so easy to do. If there are 10 cables you would have to de-rate to 50%

 

[david]

Not so easy to do. If there are 10 cables you would have to de-rate to 50%

True you could separate them into a couple of groups without doing each one individually

 

[don_resqcapt19]

Bundling is not defined by the NEC so if the inspector thinks that it's okay it's good enough for me.

The ampacity adjustment rule does not use the word "bundled". It requires that you "maintain spacing" between the cables to avoid a requirement for ampacity adjustment. To me that is saying if you want to avoid the ampacity adjustment, you have to do something to maintain the spacing.

 

[Elect117]

If someone has ETAP they might be able to model it. The ones in the middle will have a harder time dissipating heat. The demand factor for each feeder will likely help keep it from over heating. Meaning, not every feeder is 100% all the time.

I also think that strap might not be enough for the weight. I would put money that in 5 years, it will be leaning or weighing down on the black conduit (whatever it is). Kind of looks like insulated flexible tubing. It could also be the picture. The weight looks to not be perfectly vertical to the flat section of the support. It looks bent and the center of the weight is more towards the angle. That would imply that over time the weight will continue to push into that angle. That can either loosen the top screw point or bend the metal. Maybe ask for the manufacturer and check the spec for the weight.

To calculate the weight at that point,

(Length of the left span + length of the right span ) * (weight of the cable ) * (# of cables)

 

[AC\DC]

The ampacity adjustment rule does not use the word "bundled". It requires that you "maintain spacing" between the cables to avoid a requirement for ampacity adjustment. To me that is saying if you want to avoid the ampacity adjustment, you have to do something to maintain the spacing.

That’s vague also. How much is proper spacing? 1/8” - 1/2” - 1’. They should have a bare minimum.

 

[electrofelon]

As Trevor stated there is no clear definition of bundling. For instance, how much space is required between cables to not be bundled? The case of bundling may be an authority having jurisdiction call. In this case I would probably consider it bundling but as you see there are places where the cables do have space between them.

But isn't everyone leaving out the "..... Without maintaining space for a continuous length greater than 24 in" part? In other words, all you have to do is stick some spacers in there every two feet and then the derating doesn't apply.

 

[Dennis Alwon]

That’s vague also. How much is proper spacing? 1/8” - 1/2” - 1’. They should have a bare minimum.

That is the problem---- 1/100", 1/1000" etc....lol

 

[jap]

I agree the spacing is not defined.
In the attached pic I think it'd be hard to find more than 24" of cables that didn't have some type of gap between them however slight a gap that might be.

I say let it rock and roll.

Otherwise I guess one could spiral wrap a couple of them with kite string before zip tying them together.

Jap>

 

[don_resqcapt19]

That’s vague also. How much is proper spacing? 1/8” - 1/2” - 1’. They should have a bare minimum.

There was a proposal for one cable or wire diameter a couple of cycles ago but it failed.
My point is that the ampacity adjustment occurs when you don't take active measures to maintain spacing.

 

[electrofelon]

There was a proposal for one cable or wire diameter a couple of cycles ago but it failed.

Nice. Always best to keep it vague and undefined so everybody will be unsure what to do and wondering if they'll pass their inspection.

 

[jaggedben]

That’s vague also. How much is proper spacing? 1/8” - 1/2” - 1’. They should have a bare minimum.

Not touching.