JJspark
Member
- Location
- Denver, Co., U.S.A
where in the code is the table for jacketed cable such as Belden Foil?:blink:
Jacketed cable (Belden)
- Thread starter JJspark
- Start date
- Status
- Location
- Chapel Hill, NC
- Occupation
- Retired Electrical Contractor
What is this cable used for? I doubt the nec will address the cable by the brand. Is it communication cable? alarm? What are the letters of the cable?
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JJspark
Member
- Location
- Denver, Co., U.S.A
It is type CMR ,#18awg. it is used for 4-20ma signal on transducers
K8MHZ
Senior Member
- Occupation
- Electrician
CMR is covered under 800.179(B) and is also allowed as a substitute for other cables as shown in 725.154(G)
JJspark
Member
- Location
- Denver, Co., U.S.A
I'm looking to find how to do pipefill with jacketed cable such as CMR.
K8MHZ
Senior Member
- Occupation
- Electrician
You will have to do some math.
You need to find the outer jacket diameter and calculate from there. I don't know if this is what you have, but it shows a diameter of .334 inches.
http://www.belden.com/techdatas/english/1232A1.pdf
You also need to pay heed to the minimum bend radius.
So you don't have to worry about voltage drop.
I also believe these cables are exempt from normal pipe fill rules. It is a matter of what you can fit and pull. If it is a straight run, may not be too hard. If you have some bends, you may want to stay within normal fill rules.
weressl
Esteemed Member
Can you cite the NEC Article for this alleged provision/exception?
take a look at 800.110 ('08 NEC) last sentence
weressl
Esteemed Member
That is not citing:lol:
K8MHZ
Senior Member
- Occupation
- Electrician
Plus, it only applies to communications circuits.
"voice, audio, video, data, interactive services, telegraph (except radio), blah, blah blah" and includes outside wiring (not inside) for alarms.
It does not apply to the cable itself. If the cable is used outside the scope of Article 800, the fill requirements still apply. For example, if they were used for remote control, signalling or power limited circuits, they would not be exempt from fill requirements.
- Location
- Illinois
- Occupation
- retired electrician
4-20ma cable would be covered by Article 725, not 800.
K8MHZ
Senior Member
- Occupation
- Electrician
Also, the exception cited applies to ANY communications wire or cable. For instance, if I was using THHW for telegraphy to send Morse Code or RTTY, the THHW would be exempt from the tables in Chapter 3 and Chapter 9.
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K8MHZ
Senior Member
- Occupation
- Electrician
It's not the 4-20 mA that puts him in 725, its the 'signaling for a transducer' that does.
K8MHZ
Senior Member
- Occupation
- Electrician
I guess it way my error mentioning Art. 800 in the first place. Yes, the cable is covered there, but in this case we need to follow 725.
Throwing 800 in seems to have caused a distraction. Sorry.
kwired
Electron manager
- Location
- NE Nebraska
Whether the cable is subject to raceway fill rules or not, I would still want to take into consideration just how full the raceway is going to be and how hard it may pull. No point in running a particular raceway size at all if the total area of cables to be pulled through is larger than the raceway, but I still think I would want only near 40% fill for ease of installation purposes than to jam it as full as possible.
K8MHZ
Senior Member
- Occupation
- Electrician
I don't know why 800 has the exemption, really it makes no sense.
How does the application (after the fact) determine fill? I don't see that anywhere else but 800.
I guess I started kind of a mess with the fill rules exception. I agree - if ignoring fill rules is fine for CM circuits, why not for NEC 725 circuits? The inspector may not know the application of the circuit. He can guess by the marking on the cable (CM -vs- CL2, but CM is a permitted substitute for CL2). I deal with many items that have a USB interface (switch panels, lighted displays, etc). We use a USB to Cat5 converter/extender and the in wall Cat5 with RJ45 wall plates to extend these back to a source controlling computer. One day, those in wall cat5's could be ethernet (communications) and another day USB remote control (NEC 725 maybe).
I think the differences between 725 and 800 are hard to reconcile many times. Am I communicating with a transducer (sending on/off data or reading its value), remote controlling a transducer, or is it a power limited circuit? From reading the scope of 725, it seems to apply when you're building a control circuit from discrete things -- a CL2 power source, a switch, a doorbell, a relay, maybe a transducer. Although most communications interfaces are inherently power limited, they are generally not labeled as a power limited CL2/CL3 power source unless there is some CL2 wall wart that powers the whole thing. I think only a circuit which uses a CL2/CL3 power supply and perhaps some other discrete items will put you into NEC 725. If you have some type of control box that isn't listed as a power limited supply, which then has some external low voltage low current wires which goes to some item, I'm not so sure NEC 725 applies.
Finally, CL2 and CM cables are permitted to share the same raceways. If you mix, whose fill rules do we use -- 725 or 800?
I think the differences between 725 and 800 are hard to reconcile many times. Am I communicating with a transducer (sending on/off data or reading its value), remote controlling a transducer, or is it a power limited circuit? From reading the scope of 725, it seems to apply when you're building a control circuit from discrete things -- a CL2 power source, a switch, a doorbell, a relay, maybe a transducer. Although most communications interfaces are inherently power limited, they are generally not labeled as a power limited CL2/CL3 power source unless there is some CL2 wall wart that powers the whole thing. I think only a circuit which uses a CL2/CL3 power supply and perhaps some other discrete items will put you into NEC 725. If you have some type of control box that isn't listed as a power limited supply, which then has some external low voltage low current wires which goes to some item, I'm not so sure NEC 725 applies.
Finally, CL2 and CM cables are permitted to share the same raceways. If you mix, whose fill rules do we use -- 725 or 800?
- Location
- Massachusetts
Damn, the rest of us have been running raceways without considering if the conductors would fit.
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