Bundling Romex

[Dennis Alwon]

So, if you have a bunch of wire converging on an SE panel and they are parallel for 24" or more they must all be derated by a factor of 80 to 35% depending on the number of current carrying conductors, unless you "maintain adequate spacing" between them.

Where does the word parallel come in the NEC in reference to this. I believe the word is bundling. Parallel runs of cable are not necessarily bundled.

 

[infinity]

Where does the word parallel come in the NEC in reference to this. I believe the word is bundling. Parallel runs of cable are not necessarily bundled.

I agree, and I find the entire argument somewhat silly. Most homerun cables within a dwelling will have very little load on them at any given time. There are theoretical reasons why we do things but that doesn't mean it really makes a difference in the real world.

 

[ohm]

Where does the word parallel come in the NEC in reference to this. I believe the word is bundling. Parallel runs of cable are not necessarily bundled.

310.15 (B) (2) (a) does not use the word "parallel" but it refers to "cables are installed without maintaining spacing for continuous length longer than 600 mm (24 in.) " etc.

"Bundling" was a way to describe ty-wraped, laced, closely spaced method wire or cable, normally associated with good workmanship. It (bundling) is being phased out of the code.

 

[Dennis Alwon]

310.15 (B) (2) (a) does not use the word "parallel" but it refers to "cables are installed without maintaining spacing for continuous length longer than 600 mm (24 in.) " etc.

"Bundling" was a way to describe ty-wraped, laced, closely spaced method wire or cable, normally associated with good workmanship. It (bundling) is being phased out of the code.

So wires that are paralleled may have a space. Those wires may be spaced a 1/16". The code does not give us a guideline to use on how much space. Logic, IMO, tells me that if there is any space around the counductors then the heat will dissipate. I don't see an issue.

 

[ohm]

I agree, and I find the entire argument somewhat silly. Most homerun cables within a dwelling will have very little load on them at any given time. There are theoretical reasons why we do things but that doesn't mean it really makes a difference in the real world.

I agree, I notice my Lincon welder has the electrode leads comming out of two separate holes of a steel panel. I weld for hours at 175 A and the space between the holes remains the same as the rest of the box. I think some of the stuff we're forced to do does not apply to resi or small applications.

 

[ohm]

So wires that are paralleled may have a space. Those wires may be spaced a 1/16". The code does not give us a guideline to use on how much space. Logic, IMO, tells me that if there is any space around the counductors then the heat will dissipate. I don't see an issue.

What is the code ref to 1/6". I agree it's probably fine but as I stated in my original post..this section of the code is hard to enforce and probably not needed at the resi level.

 

[Dennis Alwon]

What is the code ref to 1/6". I agree it's probably fine but as I stated in my original post..this section of the code is hard to enforce and probably not needed at the resi level.

It was a hypothetical measurement to make a point. If there is space it should not be an issue. I would even go so far as to say if the nm cables are parallel and only touch on the sides this should not be an issue because only 2 wires are bundled at that point.

 

[ohm]

It was a hypothetical measurement to make a point. If there is space it should not be an issue. I would even go so far as to say if the nm cables are parallel and only touch on the sides this should not be an issue because only 2 wires are bundled at that point.

On a resi scale I totally agree. I fact if they were all ty-wraped so light would not even penetrate to bundle there would probably would not be a noticeable temperature rise. Which caused me to raise the issue in the first place.

But, If you crank the numbers using 310.15 (A) I'll bet you would get a slight increase in temperature.

 

[Legrand]

I got dinged on it about two weeks ago, 5 nm home runs together, we had to add spacers in each bay to seperate them.

 

[220/221]

Bundling romex cause no issues in real life.

Out here we always bundle ALL the home runs and enter the service outside in a single KO. Always have.

I have upgraded many many services over the years, probably in the hundreds.

The wiring is always pristine at the point where they enter the panel. I know this because I often have to strip away sheathing to give me enough wire to reach the new bus and breakers.


Bundling is only an issue to someone sitting at a desk who has never spent time in the field.

 

[ohm]

I got dinged on it about two weeks ago, 5 nm home runs together, we had to add spacers in each bay to seperate them.

Did the cite the Code ref. ? What was too close?

 

[ohm]

Bundling romex cause no issues in real life.

Out here we always bundle ALL the home runs and enter the service outside in a single KO. Always have.

I have upgraded many many services over the years, probably in the hundreds.

The wiring is always pristine at the point where they enter the panel. I know this because I often have to strip away sheathing to give me enough wire to reach the new bus and breakers.


Bundling is only an issue to someone sitting at a desk who has never spent time in the field.

I see nothing wrong with putting a 2" PVC 18" long nipple on the back of a NEMA 3R SE panel (from a crawl space) and bringing a bunch of NM into it as you mentioned. A little electrical putty to seal it and it's a fine installation. Except it's not a complete conduit system and so it's illegal.

Once you get into the panel you dress all the wires nice and pretty and ty-wrap them for 2 or 3 feet and get an atta-boy from the inspector...for all that pretty bundling. Never once seen the wires get hot because of it in a resi OR a MCC.

 

[steelersman]

Bundling is only an issue to someone sitting at a desk who has never spent time in the field.

I love this statement! I wish I could've said it better but I can't.

 

[steelersman]

I see nothing wrong with putting a 2" PVC 18" long nipple on the back of a NEMA 3R SE panel (from a crawl space) and bringing a bunch of NM into it as you mentioned. A little electrical putty to seal it and it's a fine installation. Except it's not a complete conduit system and so it's illegal.

I'm not sure that what you say is correct. I see nothing wrong with sleeving some cables in PVC for protection, although in this situation it's probably not even necessary to have the sleeve and I don't think 220/221 said that he uses a PVC sleeve did he?

 

[infinity]

I see nothing wrong with putting a 2" PVC 18" long nipple on the back of a NEMA 3R SE panel (from a crawl space) and bringing a bunch of NM into it as you mentioned. A little electrical putty to seal it and it's a fine installation. Except it's not a complete conduit system and so it's illegal.

A similar installation is permitted by 312.15(C)Exception.

Once you get into the panel you dress all the wires nice and pretty and ty-wrap them for 2 or 3 feet and get an atta-boy from the inspector...for all that pretty bundling. Never once seen the wires get hot because of it in a resi OR a MCC.

This type of bundling is generally permitted by the exception in 310.15(A)(2).

 

[electricmanscott]

Bundling romex cause no issues in real life.

Out here we always bundle ALL the home runs and enter the service outside in a single KO. Always have.

.

What Kind of connector do you use?

 

[peter d]

What Kind of connector do you use?

A 2 1/2" plastic snap in bushing of course.

 

[ohm]

A similar installation is permitted by 312.15(C)Exception.

True, but I believe you meant 312.5 (C), except (d) speaks of the end of the raceway being "sealed or plugged at the outer end using approved means so as to prevent access to the enclosure through the raceway". I suppose electrical putty fills that mandate (trip to the white book later).

(b) also says the must extend directly ABOVE the enclosure, not laterally behind it for some strange reason.

(c) also states each NM sheath must extend at least 1/4" into the enclosure, which is OK, but probably not necessary.

(g) prohibits filling the nipple, which contradicts (d) which says the raceway must be plugged.


This type of bundling is generally permitted by the exception in 310.15(A)(2).

True, it offers some relief, but IMO not enough.

I did a lot of liquid heat tracing in a previous lifetime and learned the hard way that if you have two tubing runs side by side you can add heat to one (process fluid) by running hot tracing fluid in the other. And, you can drop the temperature in the process fluid by adding cool tracing fluid as well.

My point is bundling may actually LOWER the temperature of the hot wire by "heat sinking" if all the other wires are running cool.

 

[iwire]

Whatever we think we know.

Whatever we think we have seen (or not seen)

However how many years we have been doing this.

No matter how many times we have seen derating rules entirely ignored with no ill effects.

All of it means nothing, it is my prediction the code is only going to get more restrictive in regards to bundling and derating.

My own way of dealing with it is to just change how I wire to keep up with the current NEC and not worry about why they changed the rules only that they have.

 

[iwire]

My point is bundling may actually LOWER the temperature of the hot wire by "heat sinking" if all the other wires are running cool.

Sure it might, if only one circuit was running hot. But does is not make sense that a safety code would have to be written in such a way that it is still safe under any reasonably possible conditions?