david
Senior Member
- Location
- Pennsylvania
there is a difference, what we do with the 14's ,what we do with 12's , what we are required to do with the equipment grounds.
some choice to join them all together
Parallel EGC
- Thread starter Dennis Alwon
- Start date
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there is a difference, what we do with the 14's ,what we do with 12's , what we are required to do with the equipment grounds.
some choice to join them all together
LarryFine
Master Electrician Electric Contractor Richmond VA
- Location
- Henrico County, VA
- Occupation
- Electrical Contractor
Well, if the box is metallic, and each circuit attaches to at least one device, they're effectively joined anyway, and there is no specific rule for isolation, so joining all must be at least acceptable, if not directly required.
al hildenbrand
Senior Member
- Location
- Minnesota
- Occupation
- Electrical Contractor, Electrical Consultant, Electrical Engineer
The main rule doesn't seem to have a lot of wiggle room "all EGCs associated with any. . . " "shall be connected."
I always use what I think is common sense and safety, then look at the code to see if there is a problem.
Seeing someone pretzel the code to work under a certain condition that is A typical is not my first choice.
Interpreting the code is not what it's for. Understanding why it is written in the first place is a better way to go, IMHO.
Seeing someone pretzel the code to work under a certain condition that is A typical is not my first choice.
Interpreting the code is not what it's for. Understanding why it is written in the first place is a better way to go, IMHO.
- Occupation
- Licensed Electrician
No. You have always had to have an egc sized from table 250.122.
This is a reference to parallel. This thread is trying to parallel two EGC's. Well, don't try less than 1/0
- Location
- Placerville, CA, USA
- Occupation
- Retired PV System Designer
I had not initially considered the situation of a single (non-paralleled) set of ungrounded conductors in a raceway or tray with a wire EGC constructed as a parallel set of wires. Possibly to accommodate the need for an oversized (larger than ungrounded conductors) EGC.
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Sent from my XT1585 using Tapatalk
- Occupation
- Licensed Electrician
I'm not sure what you are saying, but you are not permitted to parallel a bunch of 1/0 to get a larger egc. That is what this thread was about when it began.
If I was going to try this, I would at least not try and pull parallel runs under 1/0 since this is the minimum size to parallel for feeder conductors.
This problem is hypothetical. No one will do this or appears, has never tried.
- Location
- Chapel Hill, NC
- Occupation
- Retired Electrical Contractor
The problem is hypothetical but could be a real situation. In fact, someone had asked a similar question elsewhere. They wanted to run 2-350 kcm instead of one 700 kcm for the equipment grounding conductor.
al hildenbrand
Senior Member
- Location
- Minnesota
- Occupation
- Electrical Contractor, Electrical Consultant, Electrical Engineer
It's not that hard to do. The last 400 Amp feeder I did, I paralleled two sets of conductors in two separate conduits, BUT, both EGCs had to be full sized #3. Right there: #3 is smaller than your "1/0" limit and the #3s are paralleled.
Now, as in Dennis' scenario, let's say I built my 400 Amp feeder with paralleled phase and neutral conductors, all in a single conduit. As I have learned in this thread, only one EGC is required in the single conduit and that is sized by Table 250.122 as #3. However, if I paralleled a pair of EGCs in this same single conduit, per Table 250.122 and 250.122, they have to both be #3.
david
Senior Member
- Location
- Pennsylvania
Ok so equipment ground association with the circuit conductors has little to do with it.
If conductors are spliced in a box all equipment grounds in the box except isolated equipment grounds have to be tied together.
Unless I slip a dividing plate between the different circuits and compartmentalize the devise box
Where in the code does it say you can parallel #3 wire? Now, there is a section that says you cannot parallel under 1/0. If I was an inspector, I would fail the #3 before thinking about the parallel of two EGC's. If I saw 2 EGCs that were paralleled 1/0 or above, made the conduit fill requirment, I would pass it.
- Location
- Chapel Hill, NC
- Occupation
- Retired Electrical Contractor
What Al was saying is that he had 2 conduits and each conduit had to have a full size egc. A #3 copper is required for 400 amp overcurrent protective device. He had 2 conduits and had #3 awg in each. These were eventually tied together at both ends thus they are parallel.
Yes, they are eventually paralleled at the end. I'm with you there...
david
Senior Member
- Location
- Pennsylvania
by the way the 2014 NEC 250.148 does not say what you copied and pasted from 2017 in post #83
2017 NEC
250.148 Continuity and Attachment of Equipment Grounding Conductors to Boxes. If circuit conductors are spliced within a box or terminated on equipment within or supported by a box, all equipment grounding conductor(s) associated with any of those circuit conductors shall be connected within the box or to the box with devices suitable for use in accordance with 250.8 and 250.148 (A) through (E).
david
Senior Member
- Location
- Pennsylvania
In my opinion they are not paralleled conductors rather they have paralleled paths
The NEC in situations like health care will dictate metal wiring methods to insure paralleled paths for the equipment grounding (bonding) of a facility
A paralleled conductor is taking two or more smaller conductors to achieve a single larger conductor if that is not the purpose of the paralleled paths than they are not paralleled conductors
We all know this but until we present our arguments that way, how will we get this resolved?
90 % in this thread already have their mind made up I am 98 % there
al hildenbrand
Senior Member
- Location
- Minnesota
- Occupation
- Electrical Contractor, Electrical Consultant, Electrical Engineer
Gary, look at the General Rule of 310.10(H):
I don't see Equipment Grounding Conductors included in the list of conductors in this rule that establishes the 1/0 and larger limit.
Hello!
Yes, Im not surprised. And I never thought someone would try to parallel an ECG in the same conduit. But, that is what the thread was based on. It's a good idea for large wires that are hard to purchase.
I said I was the inspector. I am the AHJ. Since this is a bastard installation and not anything I have ever seen in the codebook,
I would not pass two #XX less than 1/0 in the same conduit to make the right size single wire that is approved by the code, which is under 310.10(H) for parallel conductors for load. If they tried this under a bigger breaker, which would require a bigger wire, and they paralleled those large wires and larger than #1, I would approve it.
I have no idea why they limit parallel on conductors to 1/0 and larger, but I see no reason now to allow two smaller in parallel now to trip a breaker when they wont allow it for the load. Under fault, it is a load.
If you have two conduits with feeders in parallel, it only takes one conduit with proper ECG fault to trip the breaker. But it takes two conduits in parallel to get the ampacity you want. There is a difference here when it comes to parallel, IMO
Guys, this is just an opinion.
It's nice being the AHJ.
al hildenbrand
Senior Member
- Location
- Minnesota
- Occupation
- Electrical Contractor, Electrical Consultant, Electrical Engineer
Think about Augie47's quote from Soares . . . the EGC has to be full sized because if there is a line to EGC fault in a run of parallel energized conductors the fault current into the EGC will come from both directions (from both ends) along the energized conductor. If you have only one of two conduits with a proper EGC, how do you know before hand that that is the conduit that will have the line to EGC fault?
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