service conduits

Status
Not open for further replies.
E

elect4

Member
Location
georgia
does anyone know where in the code that you can install all the same phases in each conduit of a parallelled installation say for instance 4 3inch conduits with 400mcm and all a phases in one conduit, b phases in another etc.. i seen it in the code years ago when i saw it at a job
 
elect4 said:
.. i seen it in the code years ago when i saw it at a job
Click to expand...

Did you notice vibration and heat associated with that installation?

Article 300.3(B)1 exception only allows it.

Exception: Conductors installed in nonmetallic raceways run underground shall be permitted to be arranged as isolated phase installations. The raceways shall be installed in close proximity, and the conductors shall comply with the provisions of 300.20(B).
 
elect4 said:
does anyone know where in the code that you can install all the same phases in each conduit of a parallelled installation say for instance 4 3inch conduits with 400mcm and all a phases in one conduit, b phases in another etc.. i seen it in the code years ago when i saw it at a job
Click to expand...

I am not sure this install was ever legal. You may be thinking you can have your neutral phase A phase B and phase C in one conduit and then have the parallel conductors in another conduit.
 
elect4 said:
does anyone know where in the code that you can install all the same phases in each conduit of a parallelled installation say for instance 4 3inch conduits with 400mcm and all a phases in one conduit, b phases in another etc.. i seen it in the code years ago when i saw it at a job
Click to expand...


Do not forget that the utility company will have something to say about this type of installation for services.
In lower NY, it is almost impossible to get the utility to give permission for this type of installation.
 
Dennis Alwon said:
I am not sure this install was ever legal. You may be thinking you can have your neutral phase A phase B and phase C in one conduit and then have the parallel conductors in another conduit.
Click to expand...

Dennis I have personally done isolated phase installations twice with 3000 amp services using the exception RUWired pointed out.

Keep in mind that the exception has strict requirements. :smile:

In my case the power company did not care how I ran the conductors all they cared about was that I used the lugs they liked at the pad mount. :smile:
 
iwire said:
Dennis I have personally done isolated phase installations twice with 3000 amp services using the exception RUWired pointed out.

Keep in mind that the exception has strict requirements. :smile:

In my case the power company did not care how I ran the conductors all they cared about was that I used the lugs they liked at the pad mount. :smile:
Click to expand...

I was not clear butRUwired mentioned the exception so I didn't.

Curious thou-- what would be the reason to do it this way vs the standard method. It obviously must have an advantage but I don't know what it is.
 
Dennis Alwon said:
Curious thou-- what would be the reason to do it this way vs the standard method. It obviously must have an advantage but I don't know what it is.
Click to expand...

In both cases I had eight sets of 600 copper to land, also in both cases the lugs where only about 16" above the conduits. That leaves very little space to chris cross the 32 - 600 Kcmil conductors.

But at the pad mount transformer there is plenty of room.

Here is an example but this one is not crowded at all compared to the ones I did.

Als_Isolated_Phase.JPG
 
iwire said:
Dennis I have personally done isolated phase installations twice with 3000 amp services using the exception RUWired pointed.
Click to expand...
I know its allowed by the NEC, but may I ask why would you or anyone want to do that? Is there an advantage that I'm not seeing?
 
Thank you. I was thinking that might be the case but since I don't ever touch that stuff I was not sure. Heck I don't believe I ever hooked up a parallel feeder---- vaguely remember something about 35 years ago but my memory is going with my hair.:grin:
 
chevyx92 said:
I know its allowed by the NEC, but may I ask why would you or anyone want to do that? Is there an advantage that I'm not seeing?
Click to expand...

It sure helps you keep all of your conductors (per pahse) the same length.
looks neat also, and, not that antone would ever mark phases incorrectly, it would be almost impossible here.
 
augie47 said:
It sure helps you keep all of your conductors (per pahse) the same length.
looks neat also, and, not that antone would ever mark phases incorrectly, it would be almost impossible here.
Click to expand...
I see that from Iwires pic now. Looks good.
 
Dennis Alwon said:
I was not clear butRUwired mentioned the exception so I didn't.

Curious thou-- what would be the reason to do it this way vs the standard method. It obviously must have an advantage but I don't know what it is.
Click to expand...

It is easier to get all of the phase conductors the same length, makes for a cleaner looking installation if the conduits are placed under their termination points.
 
but the conduits would have to be strictly pvc correct with no metal elbows or rebar close to the pipes because of inductive heating
 
RUWired said:
Nice job on the wiring and the lay out.
Click to expand...

It is, but I can not take credit, that work was not done by anyone I know. My coworker sent me this picture he took during an IR scan.

I don't have any good pictures of the two 3000 amp services I did.
 
iwire said:
It is, but I can not take credit, that work was not done by anyone I know. My coworker sent me this picture he took during an IR scan.

I don't have any good pictures of the two 3000 amp services I did.
Click to expand...


Well, if that's the case Bob, don't leave us hanging. Where's the IR image:confused:
 
Status
Not open for further replies.
Top