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#23748 - 03/26/03 06:04 PM 320A MB into 2 200A MDPs?
sparky66wv Offline
Member

Registered: 11/17/00
Posts: 2339
Loc: West Virginia
Pardon my ignorance on services of this size:

I have a commercial bid for a service that will start out with a 320A meterbase, go to a disconnect, then be split into two 200A Feeders for two 200A Panels.

1) Does the Disco need to have Main protection at 320A? (Odd size...)

2) Does the Disco need to have two 200A Branch Circuit Protection, one for each feeder?

3) If not, how do I connect two 3/0 Cu Conductors to one lug?

I haven't done any services over 200A as a contractor and none after inspections were required, so I'm not sure if the way I was taught is right...



Thanks in advance...

-Virgil
_________________________
-Virgil
Residential/Commercial Inspector
5 Star Inspections
Member IAEI

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#23749 - 03/26/03 06:35 PM Re: 320A MB into 2 200A MDPs?
Electric Eagle Offline
Member

Registered: 04/20/02
Posts: 928
Loc: Alpharetta, GA
I know on residential we use a 320 MB with 2 - 200amp disco's. The MB will have double barrel lugs so you can go to each disco.(Sometimes we have to change the lugs)

I've never understood why they let us have 400 amps off a 320 meter.

I'm not sure if this helped you or not.

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#23750 - 03/26/03 06:40 PM Re: 320A MB into 2 200A MDPs?
HotLine1 Offline

Member

Registered: 04/03/02
Posts: 6804
Loc: Brick, NJ USA
Virgil:
What you outlined is used for large resi around here. It's a 400 @ 80%. Commercial is usually all calc as continuous load....but that should be the call of your POCO.

If you need a main disco then it has to be a 400.

How about you do this:
Meter pan to a troff; parallel 3/0 & tie the ends together.
Get two 200 amp main CB panels.
Tap 1 set of 3/0 to each panel from troff.

The above is based on your panels being back-to-back with the meter, otherwise you need the disco at point of entry.

If the 320 meter base is unavailable....
Service into troff, either parallel 3/0 or 500 MCM
Tap 3/0 to each meter base (200 single meter)
Run to your panels.

John
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John

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#23751 - 03/26/03 07:20 PM Re: 320A MB into 2 200A MDPs?
sparky66wv Offline
Member

Registered: 11/17/00
Posts: 2339
Loc: West Virginia
Thanks guys, here's more info:

400A (320A Nominal) MB into 400A (320A Nominal) Disconnect with 500 KCM Cu.

Then, with double lugs on load side, splitting into two runs of 3/0 Cu (w/ a #4 EGC) to each 200A panel.

The MB and disco will be side to side, there is about 20' to the location of the 200A panels inside.

Then, the two original 100A panels will be fed off of the Lighting Panel (200A) off of 100A CB's and the new HVAC stuff will be on the Power Panel (200A).

The two 100A subs are 100' and 130' away respectively.

I'll have to core drill two 2-12" holes and 4 1-3/4" holes, and run the conduit to the subs above drop ceilings.

Also, the old panels will have to have ground busses and the EGC's seperated from the neutrals.

My horribly rough estimate is about $2700 for materials and about $1200 in labor.

This figure was using the 1990 Electrical Construction Estimator.

The underground lateral and conduit is not included in the bid.

Am I anywhere near the ballpark?

BTW: I'm bidding against a local Commercial Electrical Contractor who "has done all the work here" and could pull a profitable figure out of his hat and still have me beat... So I don't want to invest too much time in this.. The GC has the contract to convert the HVAC and would rather use me (probably because I'll lose money on it and he will gain from it...)

Help!

_________________________
-Virgil
Residential/Commercial Inspector
5 Star Inspections
Member IAEI

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#23752 - 03/26/03 07:36 PM Re: 320A MB into 2 200A MDPs?
txsparky Offline
Member

Registered: 05/25/01
Posts: 578
Loc: Magnolia,.Texas U.S.A.
 Quote:
This figure was using the 1990 Electrical Construction Estimator


Damn! There's no inflation in WV?

FWIW, the labor sounds way low based on the amount of work that you described.(either that,or You and Jimmy are very fast)

[This message has been edited by txsparky (edited 03-26-2003).]
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Donnie

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#23753 - 03/26/03 07:42 PM Re: 320A MB into 2 200A MDPs?
sparky66wv Offline
Member

Registered: 11/17/00
Posts: 2339
Loc: West Virginia
OK, I tweaked the figures with Electric Eagle's idea of two 200A discos, and it dropped it down to about $2600 Materials and up to $1300 in labor for a net of $3900...

Ends up about the same...
_________________________
-Virgil
Residential/Commercial Inspector
5 Star Inspections
Member IAEI

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#23754 - 03/26/03 08:57 PM Re: 320A MB into 2 200A MDPs?
sparky66wv Offline
Member

Registered: 11/17/00
Posts: 2339
Loc: West Virginia
Sorry, Donnie, I missed your post somehow...

Actually, I had to lower the hourly wage figure from $26.26 in the book to an average of $20 per man-hour to be competitive...

And the materials vary from being either a little more or a little less than what they are here in reality. It comes close it seems...

Too low? Heck, I figured It'd be about $1000 "too high" from what the GC and Church are expecting to pay...

How many Man-hours would you count?

I figured on about 65...
_________________________
-Virgil
Residential/Commercial Inspector
5 Star Inspections
Member IAEI

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#23755 - 03/26/03 09:40 PM Re: 320A MB into 2 200A MDPs?
txsparky Offline
Member

Registered: 05/25/01
Posts: 578
Loc: Magnolia,.Texas U.S.A.
 Quote:
an average of $20 per man-hour


Theres some of the difference!
I was thinking closer to 80 hours with it being an existing building in use and having to work around others and their schedules as well as cleanup.

Donnie
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Donnie

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#23756 - 03/27/03 02:42 PM Re: 320A MB into 2 200A MDPs?
fedup Offline
Member

Registered: 10/26/01
Posts: 32
Loc: alabama
The 320 amp meterbases I have seen are rated at 100% so it can be used on a 400 amp service

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#23757 - 03/27/03 03:55 PM Re: 320A MB into 2 200A MDPs?
HotLine1 Offline

Member

Registered: 04/03/02
Posts: 6804
Loc: Brick, NJ USA
Fedup:
"The 320 are rated 100%" then they are 320 amps, right??
I'm not trying to be a smarta**.

Virgil:
You are paralleling the 3/0 feeder(s) from the 400 amp main to the 2 panels....are they the same length??? You may want to go with the 2x200 discos; might be cheaper and easier.
Just a thought.
Good Luck with the bid!
John
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John

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