New 1200 Amp Service to feed 4 200A and 1 400A Panels .......

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dionysius

Senior Member
Location
WA
Existing building has 400 Amp service with one MBP. This service is now being replaced with a new 1200 Amp service. All 3 phase 480/277V. Customer is very cost driven and wants to reuse the max amount.

An Eaton Pow-R-Line C Switchboard (NEMA type 3R) with outgoing feeds will be specified to serve:
  • One 400A feed going to existing MBP connected using existing 500 kcmil and conduit
  • Four 200A feeds each to a new 200A panel using 4/0 Al

What is the best breaker choice for the 400A feed using the existing 500 kcmil run and how to specify??

Can it be 2 parallel 200A breakers supplied from manf. I am aware of NEC 240.8 that states:
240.8 Fuses or Circuit Breakers in Parallel. Fuses and circuit breakers shall be permitted to be connected in parallel where they are factory assembled in parallel and listed as a unit. Individual fuses, circuit breakers, or combinations thereof shall not otherwise be connected in parallel.

I would like to have 6 200A breakers but how do I specify that any two of them are able to be paralleled to comply with NEC 240.8??? If that is possible then what is least expensive way to split the 500 kcmil (a 4/0 from each breaker going to a J-box with lug strips to y connect to the 500 kcmil??).
 

augie47

Moderator
Staff member
Location
Tennessee
Occupation
State Electrical Inspector (Retired)
The "factory parallel" does not apply in this situation. If you want a 400 amp feeder you need a 400 amp breaker in your panelboard.
With this upgrade in service you alos need to take a close look at your available fault current vs your breaker AIC ratings.
 

iwire

Moderator
Staff member
Location
Massachusetts
I agree with Gus, you don't get to use two 200s to make a 400.

That rule is for equipment like HVAC internal wiring etc.
 

iwire

Moderator
Staff member
Location
Massachusetts
I also agree with Gus that you may run into an issue with the fault current rating of the old equipment suppled from the new service.

You may not be able to refeed the old equipment.
 

kwired

Electron manager
Location
NE Nebraska
Beware your 1200 amp unit will need ground fault protection where the 400 amp did not.

A 400 amp breaker should be able to accept your 500kcmil conductors.


Haven't been around much Eaton, but guessing pretty much like the others on this kind of gear, purchase it all on one order and you get much better price then if you purchase it piece by piece.
 

iwire

Moderator
Staff member
Location
Massachusetts
Beware your 1200 amp unit will need ground fault protection where the 400 amp did not.

That is a great point.


dionysius , you did not mention the conductors you are using for the 1,200 side but keep in mind that 500 kcmil is not rated 400 amps so three sets of 500 copper will not get you too 1,200 amps.
 

Tony S

Senior Member
Sorry, I’m just trying to get something straight in my head. According to 240.8 fuses/circuit breakers can be used in parallel so long as the unit is factory designed.

How would the protection be arranged and is there a certain current value beyond which this is allowed?
 

iwire

Moderator
Staff member
Location
Massachusetts
How would the protection be arranged and is there a certain current value beyond which this is allowed?

As far as the NEC there is no limit, the NEC puts in the manufacturers lap and often the listing standards.

The only time I have seen it has been in HVAC equipment (or automotive equipment)

In those cases it was fuses, under 100 amps and simply put in parallel. Two 50 amp fuses in paralleled gets you 100 amps of protection.
 

iwire

Moderator
Staff member
Location
Massachusetts
Here is the section from 2014

240.8 Fuses or Circuit Breakers in Parallel. Fuses and
circuit breakers shall be permitted to be connected in parallel
where they are factory assembled in parallel and listed
as a unit. Individual fuses, circuit breakers, or combinations
thereof shall not otherwise be connected in parallel.
 

jim dungar

Moderator
Staff member
Location
Wisconsin
Occupation
PE (Retired) - Power Systems
Sorry, I’m just trying to get something straight in my head. According to 240.8 fuses/circuit breakers can be used in parallel so long as the unit is factory designed.

How would the protection be arranged and is there a certain current value beyond which this is allowed?

More than half a century ago there were some large ampacity (400A and larger) fusible switches that were built using 2 paralleled standard fuses. Today, in MV equipment, paralleled fuse elements are not uncommon above 400A.
 

iwire

Moderator
Staff member
Location
Massachusetts
Just remembered that one of my own home panels uses 100 amp breakers in parallel to get a 200 amp breaker.

Here is a photo of one from the Internet


ge200ampmain.jpg
 
I can't speak for WA but in FL that job would require a licensed PE.

Welcome to the forums.

Wow really? Id hate to be an electrician there, Seems like not all that large or complicated. No prob in Washington with an electrician designing this however some areas require plan review.

To the OP, I would think using a 1200 amp panel board with 5 disconnects would be the most cost effective route and that also gets you around the GFP requirement ( not sure if you were planning a single main). Another cost cutting strategy would be to keep the existing gear as a service and bring in another set if service entrance conductors to feed an 800 amp panel board with 4 disconnects.

As others have said, watch you fault current rating of your existing gear. If it's not that old and the same brand as the new stuff, you will probably get a series rating.
 

Cow

Senior Member
Location
Eastern Oregon
Occupation
Electrician
I agree with Electrofelon, we'd use multiple service disconnects in an MDP rather than one GFI'd main.

I also agree with the others that you will need to verify the existing equipment meets the fault current available with your new service.
 

dionysius

Senior Member
Location
WA
Feed to old panel.......

Feed to old panel.......

I also agree with Gus that you may run into an issue with the fault current rating of the old equipment suppled from the new service.

You may not be able to refeed the old equipment.

This is a superb forum. Thank you all.
As a representative example the old 480 Main Panel is populated with ITE (Imperial Corporation) EH2-B100 breakers with the following Current Interrupting Ratings printed on them: 240V 18000 Amps; 480v 14000 Amps. This is all the technical information that is available.

Can this panel be reused and if not why not???? Any help appreciated.
 

iwire

Moderator
Staff member
Location
Massachusetts
old 480 Main Panel is populated with ITE (Imperial Corporation) EH2-B100 breakers with the following Current Interrupting Ratings printed on them: 240V 18000 Amps; 480v 14000 Amps. This is all the technical information that is available.

Can this panel be reused and if not why not???? Any help appreciated.

You need to find out from the power company what the fault current is at the point of connection.

If it is above 18,000 your only hope is that the length of the service conductors will add enough impedance to drop the fault current below 18,000.

I really do not know what the typical fault current is for a 1,200 amp 480 volt service but I suspect it is over 18,000 at the utilities transformer.



By the way, I agree with the others that going with multiple service disconnects to avoid a GFP main is a good way to go.
 

mgookin

Senior Member
Location
Fort Myers, FL
Wow really? Id hate to be an electrician there, Seems like not all that large or complicated. No prob in Washington with an electrician designing this however some areas require plan review.

....

Anything over 600A residential and anything over 800A non-residential needs a PE by Florida law.
Are there thresholds in other states which you are aware of?
 

iwire

Moderator
Staff member
Location
Massachusetts
Anything over 600A residential and anything over 800A non-residential needs a PE by Florida law.
Are there thresholds in other states which you are aware of?

Here in MA I am pretty sure an electrician can design any work they are doing.

I did a upgraded a 4,000 amp 208Y/120 service to a 3,000 amp 480Y/277 service and the entire plan was a sketch my PM had made.



In practice once things get too big insurance companies and contract requirements often force the use of PEs.
 

tkb

Senior Member
Location
MA
Here in MA I am pretty sure an electrician can design any work they are doing.

I did a upgraded a 4,000 amp 208Y/120 service to a 3,000 amp 480Y/277 service and the entire plan was a sketch my PM had made.



In practice once things get too big insurance companies and contract requirements often force the use of PEs.

In MA an electrical contractor or electrician can design work that they will be installing.

Here is a link to the MGL Chapter 112 Section 81R
https://malegislature.gov/Laws/GeneralLaws/PartI/TitleXVI/Chapter112/Section81r
 
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