Nec 314.28(a)(2)

Status
Not open for further replies.

erickench

Senior Member
Location
Brooklyn, NY
The above NEC section states thus:

"The distance between raceway entries enclosing the same conductor shall not be less than six times the metric designator (trade size) of the larger raceway."

My question is this: Assume there are splices inside a pull box or handhole enclosure. If the splice count's as two conductors then how does one calculate the distance between raceway entries?
 

ibew441dc

Senior Member
The above NEC section states thus:

"The distance between raceway entries enclosing the same conductor shall not be less than six times the metric designator (trade size) of the larger raceway."

My question is this: Assume there are splices inside a pull box or handhole enclosure. If the splice count's as two conductors then how does one calculate the distance between raceway entries?


314.28(A)2 applies to Pull and Junction boxes,and conduit bodies.

The calculation would remain unchanged.
 

480sparky

Senior Member
Location
Iowegia
The size & location of the raceways determine a minimum dimension of the box. Whether or not the conductor is spliced determines the cubic inch capacity of the box.
 

RUWired

Senior Member
Location
Pa.
Adding to what DC said, 314.28(A)2 says...(2) Angle or U Pulls, or Splices. Where splices or where angle or U pulls are made,...
 

augie47

Moderator
Staff member
Location
Tennessee
Occupation
State Electrical Inspector (Retired)
I looks to me like you might be mixing apples and oranges. In calculating box fill by cu. in, a "spliced" conductor would count as two conductors.
314.28 is for condcutors #4 and larger and to a great extent the number of conductors does not matter, simply the size of the conduits.
So the 6 X between raceways involves only the racveway and not the conductor size or number.
 

erickench

Senior Member
Location
Brooklyn, NY
Okay the point is this. There does not seem to be a provision in the code for determining the distance wherever there are splices. If a splice was considered to be two conductors tied together to make them the same conductor then my question would be answered. You can have splices inside a box or handhole enclosure. The code provides a method for determining one distance but what about the other perpendicular distance? See the attached drawing.
 
Last edited:

augie47

Moderator
Staff member
Location
Tennessee
Occupation
State Electrical Inspector (Retired)
WOW! An eye opener! I see what you are saying now. I have always approached it as a splice is two conductors tied together to make one conducor and required the 6x distance for raceways containg the same conductor.
In that the rule is there for conductor damage during a pull, my approach may have been wrong all these years. If it's a spliced conductor, the distance between raceways may not be important.
 

erickench

Senior Member
Location
Brooklyn, NY
Nevertheless there should be some kind of rule. If you say the distance is unimportant because it's a splice then perhaps an exception should be written into the code.
 

augie47

Moderator
Staff member
Location
Tennessee
Occupation
State Electrical Inspector (Retired)
If everyone was a sharp as you and not dumb like me, there wouldn't need to be an exception :smile:
When I look at it through your eyes, its not the "same" conductor so there is no "rule".
Again, since the intent is wire damage and the splice eliminates the "U" pull, does the distance matter.
The raceway distance into the box still applies so the box will be big enough, its just with splices the distance between raceways isn't needed.
 

cowboyjwc

Moderator
Staff member
Location
Simi Valley, CA
That might have been where we were having our misunderstanding the other day Augie. I believe that if it's spliced then you only need to worry about the cubic inches and that's the way I was taught also, doesn't mean it's right of course :smile:. If you are pulling it through, then you need the seperation.
 

erickench

Senior Member
Location
Brooklyn, NY
Well according to Mike Holt's book "Understanding the NEC" the distance from one wall to the other should be six times the largest conduit size for this particular situation. But this is not a code rule.
 

augie47

Moderator
Staff member
Location
Tennessee
Occupation
State Electrical Inspector (Retired)
since it's a conductor entering the box, I can see the 6X to the wall.
It's the 6X between raceways that threw me the curve.
 

RUWired

Senior Member
Location
Pa.
. The code provides a method for determining one distance but what about the other perpendicular distance? See the attached drawing.

The way i see it, the perpendicular width is the combo of all the other conduits. If in your sketch the conduits are 2", the length "A" would be 16" and "B" would be based on how you arrange the entries into the box. If you lay them out flat, roughly 12" would be needed. If you stack them, then its would be how deep is the box.

Rick
 

RUWired

Senior Member
Location
Pa.
The way i see it, the perpendicular width is the combo of all the other conduits. If in your sketch the conduits are 2", the length "A" would be 16" and "B" would be based on how you arrange the entries into the box. If you lay them out flat, roughly 12" would be needed. If you stack them, then its would be how deep is the box.

Rick

Correction the length B would be 16" and "A" would be how you lay them out.
 

RUWired

Senior Member
Location
Pa.
If all the conductors are spliced in the box, then all the conduits contain the same conductors and the distance between raceways would be 6 x for each conduit that the conductors are spliced. that could be 24" plus the thickness of the conduits for the width.

Rick

The distance between raceway entries enclosing the same conductor shall not be less than six times the metric designator (trade size) of the larger raceway.
 
Last edited:

erickench

Senior Member
Location
Brooklyn, NY
Okay I have a solution to this problem. NEC 312.8 pertains to No. 4 conductor or larger installed in enclosures for switches or overcurrent devices. It states:

conductors, splices, and taps shall not fill the wiring space at any cross section to more than 75 percent of the cross-sectional area of that space.

This same rule should be written into NEC 314.28 for all boxes that contain No. 4 or larger conductor size. This would be good for starters. What I don't understand about NEC 312.8 is how the calculation is performed. We're not talking about volumes here but cross-section area which is two dimensional space.
 

augie47

Moderator
Staff member
Location
Tennessee
Occupation
State Electrical Inspector (Retired)
If all the conductors are spliced in the box, then all the conduits contain the same conductors and the distance between raceways would be 6 x for each conduit that the conductors are spliced. that could be 24" plus the thickness of the conduits for the width.

Rick

The distance between raceway entries enclosing the same conductor shall not be less than six times the metric designator (trade size) of the larger raceway.

Rick, I think Eric's contenion is that if it's a spliced conductor, its not the "same conductor" and I think he has a point. The 6X, 8X rule would still apply for entry into the box, but the 6X for conduits containing the "same condcutor" would not. The whole intent here is damage from wire pulls and if the condiuctor is spliced, what difference would it make how far apart the conduits are. When doing an angle pull or U pull, i can see the defleection between conduits being important, but on a spliced cable it does not seem it would matter. The "common raceway" section states "raceways enclosing the same conductor". If there is a splice, I would see a valid point that it;s not the same conductor. Just an opinion, of course.
 

infinity

Moderator
Staff member
Location
New Jersey
Occupation
Journeyman Electrician
Although in this case the 6X spacing between the raceways would be worthless I don't see how you can not have it and still comply.
 

RUWired

Senior Member
Location
Pa.
Augie, using the theory they are the same conductor would give you the space needed for the splice connectors.
Rick
 
Status
Not open for further replies.
Top