ECN Electrical Forum - Discussion Forums for Electricians, Inspectors and Related Professionals
ECN Shout Chat
ShoutChat
Recent Posts
Increasing demand factors in residential
by gfretwell - 03/28/24 12:43 AM
Portable generator question
by Steve Miller - 03/19/24 08:50 PM
Do we need grounding?
by NORCAL - 03/19/24 05:11 PM
240V only in a home and NEC?
by dsk - 03/19/24 06:33 AM
Cordless Tools: The Obvious Question
by renosteinke - 03/14/24 08:05 PM
New in the Gallery:
This is a new one
This is a new one
by timmp, September 24
Few pics I found
Few pics I found
by timmp, August 15
Who's Online Now
1 members (Scott35), 258 guests, and 16 robots.
Key: Admin, Global Mod, Mod
Previous Thread
Next Thread
Print Thread
Rate Thread
Page 1 of 2 1 2
#23748 03/26/03 10:04 PM
Joined: Nov 2000
Posts: 2,236
Likes: 1
Member
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...

</pardon my ignorance>

Thanks in advance...

-Virgil


-Virgil
Residential/Commercial Inspector
5 Star Inspections
Member IAEI
Joined: Apr 2002
Posts: 914
E
Member
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.

Joined: Apr 2002
Posts: 7,381
Likes: 7
Member
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


John
Joined: Nov 2000
Posts: 2,236
Likes: 1
Member
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!

[Linked Image]


-Virgil
Residential/Commercial Inspector
5 Star Inspections
Member IAEI
Joined: May 2001
Posts: 552
T
Member
Quote
This figure was using the 1990 Electrical Construction Estimator

Damn! There's no inflation in WV? [Linked Image]

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).]


Donnie
Joined: Nov 2000
Posts: 2,236
Likes: 1
Member
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
Joined: Nov 2000
Posts: 2,236
Likes: 1
Member
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
Joined: May 2001
Posts: 552
T
Member
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


Donnie
Joined: Oct 2001
Posts: 31
F
Member
The 320 amp meterbases I have seen are rated at 100% so it can be used on a 400 amp service

Joined: Apr 2002
Posts: 7,381
Likes: 7
Member
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


John
Page 1 of 2 1 2

Link Copied to Clipboard
Powered by UBB.threads™ PHP Forum Software 7.7.5