use

[cpal]

You can read the code section that applies to say that you can't use a separate EGC with the USE cable, or that you can.

All of the circuit conductors would be in the same trench, but would not be in the same cable. It is my opinion that the separate EGC is a violation of this code section.

300.5 (I) Conductors of the Same Circuit. All conductors of the same circuit and, where used, the grounded conductor and all equipment grounding conductors shall be installed in the same raceway or cable or shall be installed in close proximity in the same trench.

this language seems close to 300.3 but the last section starting with the word or shall be installed may give some wiggle room, (just a thought)

 

[don_resqcapt19]

300.5 (I) Conductors of the Same Circuit. All conductors of the same circuit and, where used, the grounded conductor and all equipment grounding conductors shall be installed in the same raceway or cable or shall be installed in close proximity in the same trench.

this language seems close to 300.3 but the last section starting with the word or shall be installed may give some wiggle room, (just a thought)

Charlie,
That section only applies to "conductors" and not to cables. It just permits a circuit run in a trench to be made up of individual conductors, in place of a cable, as long as the conductors are installed in close proximity in the trench. I don't see it as changing the rule in 300.3 when a cable is used with an separate EGC.

 

[Twoskinsoneman]

Charlie,
That section only applies to "conductors" and not to cables. It just permits a circuit run in a trench to be made up of individual conductors, in place of a cable, as long as the conductors are installed in close proximity in the trench. I don't see it as changing the rule in 300.3 when a cable is used with an separate EGC.

That's always been my interpretation but I have to agree with others that the language should be improved to make the point clear.

 

[Twoskinsoneman]

You guys might dig this

3-56 Log #2233 NEC-P03 ​

​

​

​

Final Action: Reject
(300.5(I))​

____________________________________________________________​

Submitter:​

​

​

Donald A. Ganiere, Ottawa, IL​

Recommendation:​

​

​

Revise as follows:
(I) Conductors of the Same Circuit. All conductors of the same circuit and,
where used, the grounded conductor and all equipment grounding conductors
shall be installed in the same raceway or cable or where individual conductors
are used, they shall be installed in close proximity in the same trench.​

Substantiation:​

​

​

It appears that the current wording would permit the use of a
three conductor cable containing the three phase conductors and individual
conductors for the grounded and grounding conductors installed in close
proximity in the same trench. This proposal would require that all circuit
conductors be in the same raceway, or if individual conductors are used that
these individual conductors be installed in close proximity in the trench.​

Panel Meeting Action: Reject
Panel Statement:​

​

​

The requirement is already provided in the existing text in
300.5(I) for underground raceways or cables. This section works in conjunction
with the requirements in 300.3(B)(2), where permission is given for a cable
assembly installed in accordance with Section 250.134(B), Exception No. 2, for​

dc circuits. Making this proposed change would make this dc application a
code violation in this section and a conflict with the permission in 250.134(B),
Exception No. 2.​

Number Eligible to Vote: 13​

Ballot Results: Affirmative: 13

 

[don_resqcapt19]

The CMP did not really address the intent of my proposal.

 

[cpal]

Charlie,
That section only applies to "conductors" and not to cables. It just permits a circuit run in a trench to be made up of individual conductors, in place of a cable, as long as the conductors are installed in close proximity in the trench. I don't see it as changing the rule in 300.3 when a cable is used with an separate EGC.

Don after reading the proposal I see where you are going ( I think) but I also think that 300.5 I discusses all the conductors of a circuit which might be routed in a raceway, cable, or trench.

 

[don_resqcapt19]

Charlie,
The problem I have is the code is not completely clear, at least to me, as to the issue of a cable in a trench with the EGC run in the same trench as the cable, but not a part of the cable. The intent of my proposal was to say that if you use a cable in a trench, then the EGC must be in the cable and not just in the same trench as the cable.

 

[Twoskinsoneman]

The CMP did not really address the intent of my proposal.

Sure they addressed it "The requirement is already provided in the existing text ".
They basicially said they think it already says what you want it to say.

FWIW I agree with you and thought it was a great proposal.
They should have accepted it and modified it to fix the 250.134(B), Exception No. 2,for dc circuits problem.

 

[cpal]

Charlie,
The problem I have is the code is not completely clear, at least to me, as to the issue of a cable in a trench with the EGC run in the same trench as the cable, but not a part of the cable. The intent of my proposal was to say that if you use a cable in a trench, then the EGC must be in the cable and not just in the same trench as the cable.

I understand.
How would you feel if the OP is calling URD a cable ??
something like this http://www.cable.alcan.com/alcancab...Volt+90C+Single+Layer+Ruggedized+Cable.htm???

 

[don_resqcapt19]

Charlie,
I see that as a cable and not as individual conductors.

 

[LarryFine]

So based on that I could install GRC for some of the conductors and lay the others beside it?

No, because "or" means either inside the same cable or conduit or trench. I took the OP's use uf USE to mean conductors and not a cable; certainly not a metallic conduit.

The only difference between an EGC laid alongside a cable and being bundled with it is whether it's twisted with the rest of the conductors. Clearly, that is not a requirement.

 

[LarryFine]

So larry ,.. would this , if it were in the trench also comply???

http://images.industryclick.com/files/31/412ecm11fig11.jpg

No, because it's not within the conduit.

 

[cpal]

Charlie,
I see that as a cable and not as individual conductors.

Not trying to be obstinate, but other than the twist (not a big deal @60Hz IMO) what is the down side (inductively) of a tri-plex and an EGC in the same trench. Vs a four wire factory assembled cable.


I like Larry also thought the OP was discussing cable to mean URD or individual cables (single conductors) but this discussion has expanded my view.

 

[LarryFine]

I like Larry also thought the OP was discussing cable to mean URD or individual cables (single conductors) but this discussion has expanded my view.

A non-metallic sheath, and non-metallic conduit to a degree, will have no effect on coupling between circuit conductors and the EGC, electromagnetically speaking.

 

[don_resqcapt19]

Not trying to be obstinate, but other than the twist (not a big deal @60Hz IMO) what is the down side (inductively) of a tri-plex and an EGC in the same trench. Vs a four wire factory assembled cable.

For most installations, there would be very little electrical difference between a 3 wire cable with an external EGC or a 4 wire cable as long as the EGC is kept close to the 3 wire cable. An example of what happens as the spacing between the phase conductors and EGC is increased is given in the IEEE Green Book. If you have 500 kcmil phase conductors, a 4/0 EGC and a 5500 amp fault current, the voltage drop on the EGC is 87 volts with a 2" seperation from the phase conductor, 114 volts with an 8" seperation and 143 volts with a 30" seperation. I didn't see an example of the voltage drop if the EGC is in a common cable with the phase conductors, but it would be less than with the 2" seperation.

 

[iwire]

Clearly, that is not a requirement.

Clearly if the OP is using a cable (and I think he is) the EGC has to be part of the cable. Now if he was using individual conductors I would be on board with you. :smile: