Electrician Talk banner
1 - 20 of 20 Posts

·
Registered
Joined
·
77 Posts
Discussion Starter · #1 ·
Hi all,

I have started several threads on this 600A service and have gotten some good advice. I have another question:

We are installing CT cabinet on exterior wall (underground feed) and Cutler Hammer PRL3, 600A MB panel on inside. I have spec'd the panel top fed.

Conductors to CT cabinet are parallel 400's in 1- 4" pipe. I am having trouble deciding the best way to get from the CT into the top of the panel. The panel is listed at 5.75" deep. Per Table 312.6(A) I will not have the minimum space to enter the back of the panel with parallel 400's.

I can come out of the top of the CT cab, LB through wall then LB back down but I can't find a 4" PVC LB that lists (4)400's as fitting. That leaves me with Mogul LB's. 4 of them will cost about $1000:no:. And I have to do 2 identical services = 8 = $2000.

I could use nema 1 and 3 wireways or boxes but the panels are only 20" wide. A large box on top of the panel would keep me from feeding any feeders or branch circuits out of the top.

Any creative ideas?
 

·
Registered
Joined
·
8,054 Posts
If your poco doesn't have a problem with you crossing their CTs I'd maybe go out the bottom of the ct cabinet and lb into the bottom most part of your panelboards and orientate the main on the bottom
 

·
Registered
Joined
·
77 Posts
Discussion Starter · #7 ·
I can check. If you look at my drawing you can see that they are being pretty reasonable letting me mount both the meters and the PT cabinets remote from the CT's.

The Telco also mounted their 4x8 board right in the way when the building was built and will not change it. We have to move that first but it will still be in the way.
 

·
Registered
Joined
·
8,054 Posts
I always put the ct meter right on the side of the cabinet, they prefer it that way. With open bottom ct cabinets there is usually a channel on the left side for the conductors to pass through keeping them away from the CTs. The type of cabinet you're using does not have this and I have worked in some territories where the poco would have a bird if you crossed that area. I've also worked in parts where the poco said it didn't make a difference
 

·
Registered
Joined
·
2,923 Posts
I just did a very similar service with similar (if not exact) equipment. Ours was bottom fed and we used 2 4" nipples with 500's and had no problems physically bending the wire or with bending radius.

edit: you could always decrease your wire size...parallel 500's (CU) is oversized for a 600A. Or, if you are using AL wire, switch to parallel 350 CU.
 

·
Registered
Joined
·
8,054 Posts
Deep Cover said:
I just did a very similar service with similar (if not exact) equipment. Ours was bottom fed and we used 2 4" nipples with 500's and had no problems physically bending the wire or with bending radius. edit: you could always decrease your wire size...parallel 500's (CU) is oversized for a 600A. Or, if you are using AL wire, switch to parallel 350 CU.
I think he's using parallel 400s because he has to derate due to the fact he's gotta stuff it all in one 4" pipe. If it were me I probably wouldn't worry about the wire bending space and go back to back inside the enclosures. But if it were me I wouldn't be using that kind of equipment either
 

·
Registered
Joined
·
8,054 Posts
Deep Cover said:
Correct me if I'm wrong, but if he went back to back, derating wouldn't come into play since it would be a short nipple.
We'll have to wait for the op but I believe his primary feed UG pipe is a 4" so he's pulling 400s in that to the ct line side. Off the load side he could do a number of things but yeah I'd probably go with paralleled 350s
 

·
Registered
Joined
·
77 Posts
Discussion Starter · #14 ·
Coming in the back would be 350's since it's less than 24".

This reference may help me but im not sure about the last sentence. Probably wouldnt get flagged on it anyway.

408.55Wire-Bending Space Within an Enclosure Containing a Panelboard.

(C)*Back Wire-Bending Space.

Where a raceway or cable entry is in the wall of the enclosure opposite a removable cover, the distance from that wall to the cover shall be permitted to comply with the distance required for one wire per terminal inTable 312.6(A). The distance between the center of the rear entry and the nearest termination for the entering conductors shall not be less than the distance given in*Table 312.6(B).^

Now my other issue is that the Hfd breaker im feeding only lists 400-500 kcmil range for 2 conductors. That seems strange that a 600 amp breaker wouldnt allow a code approved conductor based on 75c ampacity.
 

·
Registered
General Superintendent
Joined
·
279 Posts
Around here, there are no splices in ct cabinets. Donut style solid core ct's only. for all 3 pocos..

we dont have the option of changing anything in the CT can, whatever we pull to it is the same thing thats leaving
 

·
Registered
Joined
·
8,054 Posts
Hefty said:
The order will be placed monday so I guess I just need to tell my supplier to inform ch of the change. Thanks.
The devils in the details when it comes to ordering gear. You and your account manager should be asking each other questions to avoid stuff like that. It's a good thing it was caught
 

·
Registered
Joined
·
77 Posts
Discussion Starter · #20 ·
The devils in the details when it comes to ordering gear. You and your account manager should be asking each other questions to avoid stuff like that. It's a good thing it was caught
Glad I caught it too. Its really just me so no body to blame and nobody to check the minutia.

This is the first service like this I have done so not only do I not have all the answers, I also dont know all the questions. Like "does the breaker come stock with lugs that are sized for conductors that have been upsized for derating, or are they sized for standard 600 amp paralleled conductors?" I'll know to ask next time

Thanks for all your help
 
1 - 20 of 20 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top