ECN Electrical Forum - Discussion Forums for Electricians, Inspectors and Related Professionals
ECN Shout Chat
ShoutChat Box
Recent Posts
Lock-down Thread
by Bill Addiss - 02/27/21 01:16 PM
Northern Tool Recalls Powerhorse Generators
by Admin - 02/25/21 09:49 PM
You will never guess
by gfretwell - 02/25/21 07:48 PM
New tool
by SMOKEYBOB - 02/15/21 04:59 PM
New in the Gallery:
Facebook follies, bad wiring
FPE in Germany pt.2
Who's Online Now
1 registered members (Scott35), 21 guests, and 20 spiders.
Key: Admin, Global Mod, Mod
Previous Thread
Next Thread
Print Thread
Rate Thread
Fault Current #72670 12/06/06 09:51 PM
Joined: Jun 2005
Posts: 4
N
nwelectric Offline OP
Junior Member
We have bid a condo project with a 600a single phase meter main on each bldg with 3 200a breakers feeding 3 condos per bldg and 1 100a breaker for a house panel. The meter main is spec to have a 600a MCB. The engineer says Isc at 37,191 at service with Isc 29,246 worst case at the apartment panels. I bid using Square D components in meter main at 44k aic. If I use mcb and each 200a at 44k aic shouldn't I be good to use 10K panels (again spec as MCB panels) in the units. I would have 44k and another 44k in series. What do you think???

NW


Frank
Work Gear for Electricians and the Trades
Re: Fault Current #72671 12/06/06 10:22 PM
Joined: Jan 2005
Posts: 155
D
Dave T Offline
Member
Are the OCPDs series rated?

Re: Fault Current #72672 12/06/06 10:43 PM
Joined: Jun 2005
Posts: 4
N
nwelectric Offline OP
Junior Member
Waiting on Sq D to answer that based on their bid for service.


Frank
Re: Fault Current #72673 12/06/06 11:39 PM
Joined: Feb 2002
Posts: 182
B
Bob Offline
Member
nw
Can you give me an estimate of cost difference for the 2 options for breakers? Just curious.

[This message has been edited by Bob (edited 12-06-2006).]

Re: Fault Current #72674 12/07/06 03:11 AM
Joined: May 2003
Posts: 2,876
E
e57 Offline
Member
Most of the breaker companies have that info for series rating on-line - but are often hard to find...


Mark Heller
"Well - I oughta....." -Jackie Gleason
Re: Fault Current #72675 12/07/06 10:31 AM
Joined: Jul 2001
Posts: 599
J
JBD Offline
Member
Square D has a listing of their series ratings in their Digest (pages 2-8 and 2-9).

In general you can not apply three devices in series and still have a series rated system. You may have to change each apartment to a main lug only style.

Is this a single 600A main breaker and meter feeding seperately mounted breakers which then feed the individual apartments? Or, is it a 600A main feeding a meter center with individual combination meter sockets for each circuit (Square D type MP or EZM) which then feed each apartment?

Re: Fault Current #72676 12/07/06 12:20 PM
Joined: Jan 2004
Posts: 615
J
Jps1006 Offline
Member
Quote
In general you can not apply three devices in series and still have a series rated system. You may have to change each apartment to a main lug only style.

Well that kind of defies common sense. If it's series rated with two, wouldn't more be better? Is there an electro-mechanical reason to this or is it just because it hasn't been tested this way for the listing?

Re: Fault Current #72677 12/07/06 01:19 PM
Joined: Dec 2005
Posts: 860
R
RODALCO Offline
Member
Single Phase 600 Amps !!

Don't they share the load over three phases and bring 1Ø, 100 Amp services into the individual appartments ?


The product of rotation, excitation and flux produces electricty.
Re: Fault Current #72678 12/07/06 02:54 PM
Joined: Jul 2001
Posts: 599
J
JBD Offline
Member
Quote
Well that kind of defies common sense. If it's series rated with two, wouldn't more be better? Is there an electro-mechanical reason to this or is it just because it hasn't been tested this way for the listing?

It all has to do with dynamic impedance of the devices opening as well as the static impedance of the circuit. Because of this devices must be tested in series.

Square D does have three tier ratings for use with their multi-metering devices.


Featured:

2020 National Electrical Code
2020 National Electrical
Code (NEC)

* * * * * * *

2020 Master Electrician Exam Preparation Combos
2020 NEC Electrician
Exam Prep Combos:
Master / Journeyman

 

Member Spotlight
pcsailor
pcsailor
Minneapolis, MN, USA
Posts: 21
Joined: September 2019
Show All Member Profiles 
Top Posters(30 Days)
Popular Topics(Views)
275,482 Are you busy
209,385 Re: Forum
196,771 Need opinion
Powered by UBB.threads™ PHP Forum Software 7.7.3