Box Fill
- Thread starter svthard
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JohnJ0906
Senior Member
- Location
- Baltimore, MD
Exactly what "cables" and "conductors" do you have?
Need some more info.
Need some more info.
svthard
Member
More info
More info
A student asked me the question. He said it is CMP communication cable passing through a handy box with other conductors. Other conductors are just to power up the communication equipment; like branch circuit conductors. How does box fill apply to this situation.
More info
A student asked me the question. He said it is CMP communication cable passing through a handy box with other conductors. Other conductors are just to power up the communication equipment; like branch circuit conductors. How does box fill apply to this situation.
cadpoint
Senior Member
- Location
- Durham, NC
Not Good !
Not Good !
One should not share the same space with electrical service, the unless all the wires have the same rating (Jacket, Cover (( lets add shield)))!!!
It should not be in the same box even if, just for the power of the electronic service! Yes its code no I can't state the article!
Not Good !
One should not share the same space with electrical service, the unless all the wires have the same rating (Jacket, Cover (( lets add shield)))!!!
It should not be in the same box even if, just for the power of the electronic service! Yes its code no I can't state the article!
P
Physis 3
Guest
cadpoint said:
You can if you have a seperate compartment in the same box. But I'm without a code book and can't check it or find the section that applies.
Edit: I forget which error code applies to my change here.
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svthard
Member
Just passin thru
Just passin thru
My understanding is it can occupy the same raceway if it is used to power the communications equipment. Don't know why there is a handy box there but all cables pass thru. I see where conduit fill doesn't apply (article 800.110), if they make this statement regarding conduits where is the statement regarding box fil. I need code articles to back up any statements since i am an instructor and this is a student question. In VA were are using the 2002 version.
800.133 says i can occupy the same raceway as long as i maintain .25 in. spacing between conductors. I can not find anything about box fil so i am only left to assume that it doesn't apply to cables.
Just passin thru
My understanding is it can occupy the same raceway if it is used to power the communications equipment. Don't know why there is a handy box there but all cables pass thru. I see where conduit fill doesn't apply (article 800.110), if they make this statement regarding conduits where is the statement regarding box fil. I need code articles to back up any statements since i am an instructor and this is a student question. In VA were are using the 2002 version.
800.133 says i can occupy the same raceway as long as i maintain .25 in. spacing between conductors. I can not find anything about box fil so i am only left to assume that it doesn't apply to cables.
barbeer
Senior Member
- Location
- Pinellas County, FL
There should be no reference to box fill for communication cables in the NEC, AFAIK cram as many as you can in the box, but why would you want to? You are using the word "cable" generically and that is confusing, NM(romex) is a cable as is MC cable(obviously). Power conductors and comm cables should be separated by 1/4 inch, hard to ensure in a common raceway IMHO.
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svthard
Member
Classroom discussion
Classroom discussion
It's not if we want to cram as many as we can into the box. think of it from a classroom perspective, we have calculations that define how many conductors we can put in a given volume of box the code assigns volume to devices such as straps, clamps, and such but then students see things in the field and bring back questions. Valid questions in IMO ie.. what about cables in boxes ..... no reference in the code about cables and boxes just conduit fill. Yes i understand romex is a cable but when it enters the box insulation is removed and basically it is reduced to individual conductors. Finally #18 is the smallest size listed in the table for box fill calculations so we are to assume that conductors smaller than #18 has no fill requirements as far as boxes are concerned. sometimes these points are hard to get home to students who are just starting to study the code and who work in the field everyday. I teach my classes from the test taking perspective as most of my student will be sitting for the journeyman test in VA at some point.
Thanks for all your help
Classroom discussion
It's not if we want to cram as many as we can into the box. think of it from a classroom perspective, we have calculations that define how many conductors we can put in a given volume of box the code assigns volume to devices such as straps, clamps, and such but then students see things in the field and bring back questions. Valid questions in IMO ie.. what about cables in boxes ..... no reference in the code about cables and boxes just conduit fill. Yes i understand romex is a cable but when it enters the box insulation is removed and basically it is reduced to individual conductors. Finally #18 is the smallest size listed in the table for box fill calculations so we are to assume that conductors smaller than #18 has no fill requirements as far as boxes are concerned. sometimes these points are hard to get home to students who are just starting to study the code and who work in the field everyday. I teach my classes from the test taking perspective as most of my student will be sitting for the journeyman test in VA at some point.
Thanks for all your help
800.110 - if wires are installed using a chapter 3 method then they will meet the requirements of the chapter 3 method (paraphrased)
- this says to me that you need to calculate the conduit fill just like you normally would for any other application in chapter 9 table- after adding the nominal wire circ mils you can look up the com cables dimensions from the manufacturers cut sheets. -we regularly use this method in fire/gas detection systems for conduit fill.
-the box fill is the real question. hmmm, I'll be interested in seeing the answer to that one. if the raceway is, say 40%, I don't see where any size box would be an issue (given that reason for the fill is heat dissipation), but the question deserves an exact answer.
(a lot of cmp wire is only rated 300v - this installation will have to use the 600v rated variety, correct ?)
- this says to me that you need to calculate the conduit fill just like you normally would for any other application in chapter 9 table- after adding the nominal wire circ mils you can look up the com cables dimensions from the manufacturers cut sheets. -we regularly use this method in fire/gas detection systems for conduit fill.
-the box fill is the real question. hmmm, I'll be interested in seeing the answer to that one. if the raceway is, say 40%, I don't see where any size box would be an issue (given that reason for the fill is heat dissipation), but the question deserves an exact answer.
(a lot of cmp wire is only rated 300v - this installation will have to use the 600v rated variety, correct ?)
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cadpoint
Senior Member
- Location
- Durham, NC
nakulak said:
I get nailed for paraphrasing all the time here :roll: !
Look in 800.110...
Exception: Conduit fill restrictions shall not apply.
nakulak said:
State the article and I will go read it
I couldn't find your CMP wire to determine that in 310.13 or in the 500's.
nakulak said:
The Code says 300.2 Limitations
(A) Voltage. Wiring methods specified in Chapter 3 shall be used for 600 volts, nominal, or less where not specifically limited in some section of chapter 3.
That kind kills appling load or Box calc's doesn't it ?
300.3 (C)(1) Conductors of Different Systems.
(1) 600 Volts, Nominal, of Less. conductors of circuits rated 600 volts, nominal, of less ac circuits and dc circuits shall be permitted to occupy the same equipment wirring enclosures, cable, or raceway. All conductors shall have an insulation rating equal to at least the maximum circuit voltage applied to any conductor within the enclosure, cable, or raceway.
Buy a pinching measuring device, a digitial read out is good.
As I said it not allowed, teach me something otherwise, I go with the seperation requirement in a device box,
but not that I practice that
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