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400 Amp Service #100555
12/01/06 07:53 PM
12/01/06 07:53 PM
G
gserve  Offline OP
Member
Joined: Mar 2003
Posts: 92
Hi,I am an electrician that has done mostly residential work up to 200A service.I have a job that will require 400Amp service.Seeing I have never done one I am seeking any advise that you could give me.I have read that most of the time 2 200A panels are used.This project is a garage and I would like to use just 1 main panel.Is this impractical? Just looking for some guidance. Thanks in advance.

2017 / 2014 NEC & Related Books and Study Guides
Re: 400 Amp Service #100556
12/01/06 08:44 PM
12/01/06 08:44 PM
I
iwire  Offline
Moderator
Joined: Jan 2003
Posts: 4,391
North Attleboro, MA USA
If you use a single 400 amp panel in place of two 200s you will pay more money and have half the circuit space when it's done.

The last 400 home service I did I used a single 400 only because I had not yet seen a double 200 set up. If it comes up again I am going with double 200s.


Bob Badger
Construction & Maintenance Electrician
Massachusetts
Re: 400 Amp Service #100557
12/01/06 09:10 PM
12/01/06 09:10 PM
F
Fred  Offline
Member
Joined: Apr 2001
Posts: 449
Straughn, IN 47387
I use either a 320A metermain with (2)200A breakers installed to feed (2)200A 40ct ML panels or if they can be back to back with a 320A meterbase I use (2) 200A 40ct MB panels. I am currently upgrading a 320A service at a house to an 800A due to a 6500 sq.ft. addition. The PoCo is hitting my CT cabinet at the addition where it will feed a 800A ML panelboard with (1)400A CB to feed the old service and (2) 200A CBs to feed (2) 200A 42ct ML panels in the new addition. Houses around here keep getting bigger and stupider.

Re: 400 Amp Service #100558
12/02/06 12:30 PM
12/02/06 12:30 PM
G
gfretwell  Offline

Member
Joined: Jul 2004
Posts: 9,305
Estero,Fl,usa
I always wonder how much of that 400a actually gets used. What are these people's electric bills? Average 60a 24/7 is over $1000 a month here.


Greg Fretwell
Re: 400 Amp Service #100559
12/02/06 01:11 PM
12/02/06 01:11 PM
S
SolarPowered  Offline
Member
Joined: Jul 2004
Posts: 625
Palo Alto, CA, USA
Quote
I always wonder how much of that 400a actually gets used. What are these people's electric bills? Average 60a 24/7 is over $1000 a month here.


Generally speaking, in many places 400A service is the next step up if the load calc exceeds 200A. And, of course, the load calc is interested in making sure that the probable sustained peaks are covered; it's not about the average draw. So one might need a 400A service when the current draw averaged over the course of a month is only a few dozen amps or less.

Re: 400 Amp Service #100560
12/03/06 06:55 PM
12/03/06 06:55 PM
G
gserve  Offline OP
Member
Joined: Mar 2003
Posts: 92
So it looks like I need a 1/O GEC for 400A service based on 600 kcml conductors. Do you normally parallel them with smaller conductors? Any help on the conductor size please. Also do they make a rebar clamp for the 1.5" rebar for the 1/O conductor size?

Re: 400 Amp Service #100561
12/03/06 07:04 PM
12/03/06 07:04 PM
I
iwire  Offline
Moderator
Joined: Jan 2003
Posts: 4,391
North Attleboro, MA USA
4 AWG CU is the largest conductor you ever have to run to a concrete encased electrode.


Bob Badger
Construction & Maintenance Electrician
Massachusetts
Re: 400 Amp Service #100562
12/03/06 07:11 PM
12/03/06 07:11 PM
G
gserve  Offline OP
Member
Joined: Mar 2003
Posts: 92
Thanks Iwire. How about help with the service conductor sizing.If 600 kcml is required what 2 sizes do I need to parallel to make up this size?

Re: 400 Amp Service #100563
12/03/06 08:51 PM
12/03/06 08:51 PM
renosteinke  Offline
Cat Servant
Member
Joined: Jan 2005
Posts: 5,316
Blue Collar Country
Just a reminder to pay extra attention to your load calcs. If the calculated load is over 320 amps, then a different type of service - one with a current transformer- will be needed.

Re: 400 Amp Service #100564
12/03/06 09:38 PM
12/03/06 09:38 PM
G
George Little  Offline
Member
Joined: Jan 2004
Posts: 1,489
Michigan USA
Reno- I believe that would be true if the 320a. were a continious load. He stated that this was a residential installation and residential is not continious. He could do the calc and come up with 400a. and if the equipment were rated for 400a. he's good to go.


George Little
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