Parallel service conductors

[iwire]

The total load would need to be greater than 50% non-linear for the neutral to count as a CCC. IMO this is highly unlikely. So A-B-C-N in 4 conduits would work since no derating would be required.

I agree Rob, few buildings services will need to count the neutral as a CCC.

 

[roger]

Oops, didn't see those exceptions. Bear in mind that you may have to do some work on the enclosure, see 300.20 (B). Might get into listing trouble on that cabinet when you modify it. Typically don't see that arrangement. (for the issues listed above) Always good to learn.

Then this could said of anytime you punched a hole in an enclosure.

I must say though, when I have done this type of installation (actually have one in the works right now) it has always been in open bottom switchboards, so I didn't have to cut slots.

Another solution could be to cut a large opening in the enclosure and attach a piece of aluminum for the conduit entrances.

Roger

 

[C3PO]

Then this could said of anytime you punched a hole in an enclosure.

I must say though, when I have done this type of installation (actually have one in the works right now) it has always been in open bottom switchboards, so I didn't have to cut slots.

Another solution could be to cut a large opening in the enclosure and attach a piece of aluminum for the conduit entrances.

Roger I would love to see some pictures of this if you have any.

 

[C3PO]

In this situation the POCO is saying that they will not hook this up.
They claim that since each phase is in its own conduit(As in one, Bs in one, etc) that the harmonics will cause vibrations on the conductors that could break their lugs in the transformer. Anyone have any thoughts on this?

 

[LarryFine]

Another solution could be to cut a large opening in the enclosure and attach a piece of aluminum for the conduit entrances.

Unless I'm mistaken, while aluminum is non-ferrous, eddy currents can still be induced in it.

I believe a non-metallic substance is required for this purpose.

 

[roger]

Unless I'm mistaken, while aluminum is non-ferrous, eddy currents can still be induced in it.

Agreed, but not enough to be overly concerned about. See the FPN following the exception to 300.20(B)

I believe a non-metallic substance is required for this purpose.

D?j? vu, see the FPN following the exception to 300.20(B)


Roger

 

[roger]

Roger I would love to see some pictures of this if you have any.

It'll be awhile before the conductors are installed, this is a 4 story hotel in the Rough In stage but, I think Iwire has posted a picture or pictures in the past.

It is much easier to keep the conductors the same length (per phase) and also makes terminating easier.

Roger

 

[C3PO]

I think Iwire has posted a picture or pictures in the past.

I thought so too, but haven't been able to find them. I will keep searching.

It is much easier to keep the conductors the same length (per phase) and also makes terminating easier.

I agree, but some people in this area apparently do not. :smile:

 

[C3PO]

Just to clear up something in case anyone is thinking it. This is not a problem or arguement between me and augie47. We are both just looking for opinions about a situation that is going on in our area.

 

[iwire]

I got some pics, I will post later.

 

[kingpb]

In this situation the POCO is saying that they will not hook this up.
They claim that since each phase is in its own conduit(As in one, Bs in one, etc) that the harmonics will cause vibrations on the conductors that could break their lugs in the transformer. Anyone have any thoughts on this?

Then I guess that pretty much sums it up. A utility is not regulated by NEC, nor does the AHJ have the ability to over-rule them.

Never argue with the Utility, they are always right!

 

[roger]

In this situation the POCO is saying that they will not hook this up.
They claim that since each phase is in its own conduit(As in one, Bs in one, etc) that the harmonics will cause vibrations on the conductors that could break their lugs in the transformer. Anyone have any thoughts on this?

C3PO, I missed this post, my thoughts of what the POCO is saying is "Bull Hockey"

Roger

 

[iwire]

I would love to see some pictures of this if you have any.

Here are a couple Isolated phase installations

Here we are looking at three, 4 wire feeders in MI cable using a non-ferris entry into a panel.

 

[C3PO]

C3PO, I missed this post, my thoughts of what the POCO is saying is "Bull Hockey"

I agree. :smile:

 

[C3PO]

Here are a couple Isolated phase installations

Thanks Bob