Equivalent GEC

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mwm1752 said:
Parallel underground service conductors are joined together at each end of the lateral -- this creates a single circuit -- combined circular mills of each parallel run determine electrode conductor size -- parallel conductors specified in 310.15(H)(1) & (5) which include bonding jumpers -- 250.122(F) will mandate EGC to be a singlular sized conductor per OCPD which can be fed with parallel feeders that combine circuilar mills are adequate for the circuit -- table 250.66 ditinguishes the difference in largest service conductor and parallel conductors, in which the electrod size is referred as conductor(indicating singular) -- 250.64(D)(2) also indicates a singular conductor -- I tend to go with the electrode conductor is a singular type conductor & not to be paralleled.
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I agree with you, but in a left-handed sort. Parallel conductors are required to be the same circular mills but they are sized by their ampacity. There is no ampacity requirement for GECs, only a size requirement. That's the best reason I can think of why GECs cannot be paralleled and why no further explanation is needed in the code.
 
Although the code tends to be permissive, except were it explicitly forbids, my interpretation is that only the types of conductors explicitly named in 310.4(A) can be installed using parallel wires. If the intent were to allow paralleling EGCs and GECs, then either the code would have included them in the list or the code would not have named the others by way of a list. Also, we are given a specific minimum wire size for a GEC, but we are not given the basis upon which that size was determined. What I mean is, for a 1/0 copper service conductor, how did the code makers decide that a #6 copper GEC is sufficient? Thus, we cannot know how to judge whether a combination of two or more smaller wires would serve adequately in place of the single larger wire. We could try two smaller wires with the same ampacity as the larger wire, or we could try two smaller wires that have the same combined cross-sectional area as the larger wire, but in both instances we would be guessing as to whether that would serve the required purpose.
 
charlie b said:
Although the code tends to be permissive, except were it explicitly forbids, my interpretation is that only the types of conductors explicitly named in 310.4(A) can be installed using parallel wires. If the intent were to allow paralleling EGCs and GECs, then either the code would have included them in the list or the code would not have named the others by way of a list. Also, we are given a specific minimum wire size for a GEC, but we are not given the basis upon which that size was determined. What I mean is, for a 1/0 copper service conductor, how did the code makers decide that a #6 copper GEC is sufficient? Thus, we cannot know how to judge whether a combination of two or more smaller wires would serve adequately in place of the single larger wire. We could try two smaller wires with the same ampacity as the larger wire, or we could try two smaller wires that have the same combined cross-sectional area as the larger wire, but in both instances we would be guessing as to whether that would serve the required purpose.
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Actually the equipment grounding conductor is required at times to be run in parallel, However I agree with you that there seems to be pacific allowances when conductors are allowed to be run in parallel. The NEC does specifically state conductors in parallel shall be sized >>>>>>>> so an so.


250.122 Size of Equipment Grounding Conductors. (F) Conductors in Parallel.
Where conductors are run in parallel in multiple raceways or cables as permitted in 310.4, the equipment grounding conductors, where used, shall be run in parallel in each raceway or cable.

Each parallel equipment grounding conductor shall be sized on the basis of the ampere rating of the overcurrent device protecting the circuit conductors in the raceway or cable in accordance with Table 250.122.
 
david said:
Actually the equipment grounding conductor is required at times to be run in parallel. . . .
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But each EGC in each parallel conduit is a full-size. You can't make an equivalent of one large EGC by putting a smaller EGC in each parallel conduit, and connecting the EGCs at both ends. So it is not the same situation as the OP has presented to us.

 
charlie b said:
But each EGC in each parallel conduit is a full-size. You can't make an equivalent of one large EGC by putting a smaller EGC in each parallel conduit, and connecting the EGCs at both ends. So it is not the same situation as the OP has presented to us.
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I’m not disagreeing with you as far as equipment ground being paralleled.

If you have a paralleled supply and say it is rigid steel conduit. You can’t run a copper AWG in one conduit and use the rigid steel as the equipment ground for the other. I was just pointing out there are times that the code requires an equipment ground to be paralleled but when it does it specifies the size.

I am not aware of any situation when paralleling is allowed or required that there is not also instruction on how to size the paralleled conductor
 
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