A customer has a 3500 sq ft home and wants to upgrade his 200 amp 1Ph panel because it is full and he wants to add a 240v 50a spa, a 240v 20a waterfall and a 500 sq ft guest house with elec heat, kitchen etc. If I do this the power co will have to pull in new feeders from the transformer and I'll have to use 2 - 200 amp panels. One main 200 amp panel feeding another 200 amp load center. (As far as I know they don't make a all-in one 400 amp panel). These are outdoor panels which are mostly used here in AZ. Cost is around $1000 just for the parts.
Option 2: is possibly adding a 100 amp sub panel off the exhisting 200 amp panel, (having to make room for the 100a feeder breaker), this would be less expensive.
I'm going to amp clamp the load, also will figure the total load service calculation from the back of the code book.
Any suggestions, comments, or ideas on this?
Thanks,

Have you calculated for additional load in existing dwellings, per 220.31?
It should be less stringent, and you may be able to squeeze in on your existing service.

Have not figured load calc yet but will include that.
thanks,

Aldav

All of the big manufactures (GE, Square D, Cutler-Hammer, Siemens, Etc.) make 400 amp combination service entrance devices. You can get them with a single 400 amp breaker feeding the internal 40 circuit loadcenter or with 2-200 amp breakers, 1 feeding the internal loadcenter and the second to feed a remote panel. Square D only make one with the 2-200 amp breakers but I know GE and Cutler-Hammer makes both styles. If you need some part numbers let me know.

Curt

what type heat does the main house have. that is my rule of thumb guide to service sizes, along with sq footage. if they have gas, i'd probably use the existing service. if they have heat pumps, they're probably stretched thin already. either way heres a real time saver for figuring the load:
http://www.vickrey-s.com/SFDLoadCalc.asp

oh, if i were to upgrade to 300 or 400amp, i'd use a ct cabinet, or the newer 300amp meter base, and set the 200amp panels to each side. probably save a bundle compared to a 400 amp switch.

He has 2 electric heat pumps with 2 air handlers, but the water heater is gas.
Are those outdoor all-in-one 400a panels?

All of the 400 amp Combination Service Entrance Devices are NEMA 3R.

Here is a link to Cutler-Hammer's Combination Service Entrance devices. Look at pages 22-26 of the PDF file. http://www.cutler-hammer.eaton.com/unsecure/cms1/TD31F01TE_72DPI.PDF

Aldav,

If you go to the "Home Depot Pro", at the NW corner of Thomas and 32nd street.

In there they have 400amp all-in-ones for Square D and Cuttler Hammer.

That store is made for contractors like yourself.

About $800.00 each.

Like one of the posts said. It has two 200amp breakers. One feeds the 40 space panel built inside and the other 200-amp breaker will feed a remote panel.

The only thing that sucks is that the existing Underground PVC pipe, comming from the transformer, will be to small for SRP to pull in bigger feeders. In order to run a bigger PVC conduit, say 3" or 4", you usually have to saw cut the driveway.

I usually try to make the existing 200-amp panel work. Install a 100-amp sub panel like you said.

Good luck.

Tev

I checked with SRP and they did say they could pull in new 4/0 feeders for it but think I'll try to go with the 100 sub panel like you said instead.
Thanks,

aldav53,

Suggest you do a Load Calc first (as already suggested), and submit it to the PoCo (Utility Power Company).

Do this so they can take into consideration the "Flicker Factor" for the Heat Pumps (if they are not already existing and running).

PoCo may upgrade the service feeders, and if necessary, increase the Transformer's size.

Your Client may have to pay for the feeder upgrade, but not the Transformer upgrade (unless the PoCo finds the flicker factor too excessive and the current load on the Transformer is less than 130%).

Definitely suggest load calcs are done - and maybe done "Heavy"
(higher than normal figures)
on one calc to compare the results.
Figure an ample "Future Load" value on each calc.

You may be fine with the currently used 200 Amp service (panel and / or service feeders).
Upgrade to 400 Amp size if necessary
(or Client demands it!).
Compare current load demand against projected demand, and see if panel / service feeders need to be upgraded.

If the service panel sucks, change it!

I have only used the Square D 400 Amp Residential Service Panel - the one which is a 320 Amp Continuous rated, uses cl 320 KWH Meter, and has (2) 200 Amp 2 Pole breakers (1 for remote Sub Panel, 1 for 200 Amp bus kit within the Panel Assembly).
Had no idea that any others existed (with a 400 Amp bus kit!).
Are these listed for EUSERC (sp??) usage?

Scott35

As long as the load calc is within limits of the 200 amp panel, adding a 100 amp subpanel to it should be ok. Do they make a subpanel smaller than 100 amp? This is a possibility too.

I'm not sure I completely understand your situation so maybe I have misunderstood. The cheapest method to use and still ensure plenty of capacity is to simply use a 400A meter socket and feed out of it twice to two separate 200A panels. You would have to make sure you order lower lugs for the socket that allow two wires in each. Since nobody else has suggested this relatively cheap, simple remedy, I can only assume that I am misinterpreting your description.

Not sure what you mean by a 400 amp meter socket. This would be a 400a outdoor panel using a panel-meter combo or all-in-one, with a 200 amp main and another 200a breaker to feed another 200a subpanel.

How old is the house and what is the actual SEER rating on the A/C’s. I had an almost identical situation recently. I replaced an older 200A service with the same and added two 100A sub panels. One was side by side of the main and the other was installed near the guest house that was just built. The pool company also added another 70A Subpanel after the fact near their equipment. Haven’t seen or heard of any problems with flicker at this job or others like it. You do have to make sure that you have proper voltage from the utility under load (both before and after you do the work) and the actual loads need to remain below the main breakers rating. Yes the panel loads sound excessive but most of it is redundant and mainly for show.

Most small residential sub panels are rated for max 125A but you can always use a smaller breaker to lower the costs when 125A isn't really needed.

Looks like I'll be upgrading to the 400 amp service. I figured approx 138 or 170 amps on the exhisting service (not sure if it has the heat strip supplement on the 2 heat pumps).
He will also be adding an addition with a 72 amp load figured by the Arch. So with adding a 50a spa, a 240 20a water fall and the addition it is over the 200 amp service. I will probably install the 400 amp panel at the exhisting side of the house and add the 200 amp sub panel on the back of the house. Which means possibly piping through the garage all the way to the back.

I was thinking the same as triple. Unless there is a reason I missed such as no space for another panel side by side or the second panel is prefered in new location.

Just get 1 400 Amp pedistal WITH NO main breaker disconect for less than $400. Put that about where the old pedistal was with some sort of 90, 90/45, back to back, or Mogal LB set up. Come out of it twice with 2" (for us it is rigid) into 1 exsisting 200 amp panel and 1 new 200 amp panel.

I would think you could do this faster because you don't need to remove the old panel and cheaper than other ideas.

Tom

Tom and Triple

Since he is in Arizona this service must meet EUSERC requirements. Among other things you are not allowed to bring underground service conductors directly into a standard meter socket. An approved underground pull section must be provided for the utility to terminate their service conductors. The parts to build this service would cost more that purchasing a readily available combination service entrance device which has a pull section, meter socket and load center in one box.

We do things a little different here in the West compared to the rest of the Country.

Curt

Don't need any of that. The power co has to pull in new feeders to the panel and once I change it out they will come back to reconnect.

Caselec, are you saying that the power company wants a place to terminate wires underground before the metersocket? What is their reasoning for not wanting to terminate at the meter socket itself?

Triple

The underground pull section is mounted on the wall next to the meter or is part of the meter socket.

If you look at the picture below the pull section is the large area under the meter socket. This panel is a 400 amp combination service entrance device. It has the pull section, meter socket, 40 circuit load center and a second 200 amp breaker to feed a remote load center.

caselec,
Yep, thats the one, great picture. I will then mount the 200a load center on the back side of the house fed from the 400a on the side of the house.
The trick is to coordinate the power co to disconnect power, pull in new 4/0 feeders, then after I mount the new panel, have it inspected by the city, then reconnected by the power co - all in one day.

Yea, Adlav,

That is the trick, I often wonder if I should include some money in my bid to put a family up in a local hotel room for a night while I do a panel change out. Especially in this AZ heat.

I have never done it yet, but I think that would be a great alternative. I learned the hard way about not scheduling an appointment with the POCO architect befor a panel change out.

If you meet with the POCO architect on the job, before you start the upgrade. Then you can get scheduled in for a same day disconnect, inspections and reconnect. Otherwise you will wait at least one full day for your POCO and city inspections, then another full day for the reconnect. That is if you pass the first inspections.

Thanks to caselec for that perfect picture of the 400-amp meter combo with the two 200-amp disconnects. Not sure if it is a Square D or Cuttler Hammer though.

That is what we put on all of our big homes, like say 3,500 sq ft or more. Plenty of room for guest homes and back yard work shops.

Peace out

Tev

BTW caselec,

How do you post pictures?

Thanks in advance,

Tev

Tev, in the box you type the post in, there is a link to the left of the box "*UBB Code is On". This link will provide you with information on posting images, italics, bold type,...

Here is the info for image posting - To add a graphic within your message, just encase the URL of the graphic image as shown in the following example (UBBCode™ is in red).

[ IMG]http://www.infopop.com/artwork/footer_logotype.gif[/IMG ]
In the example above, the UBBCode™ automatically makes the graphic visible in your message. Note: the "http://" part of the URL is REQUIRED for the [img] code. Also note: some UBB forums may disable the [img] tag support to prevent objectionable images from being viewed.

The [img] and [/img] should not have spaces in them. I added them to prevent the actual image from being posted in this reply.

PS, the panel is a SquareD(right click on the image to get it's URL address).

steve

[This message has been edited by stamcon (edited 09-14-2003).]

[This message has been edited by stamcon (edited 09-14-2003).]

Are you sure about them pulling 4/0? If you have a 200 amp service now you should already have 4/0 AL. Usually the PoCo installs 350 AL for 400 amp residential services and requires a 3" or 4" duct. Make sure you have this correct or your customer may be without power for a long time if the PoCo comes out to connect it and tells you that it can't be done until you install a new duct to the street.

Curt

caselec,
Thats what the Designer from SRP (power co) said. But I will check again to make sure.

Steve,

Thanks very much for that information. So does that mean that any picture that I want to post needs to have a url?

What if I want to post a picture from one of my own files on my computer?

Thanks in advance,

Tev

caselec,
You were right, it does have 4/0 already there. I had the designer from the power co go out and actually check it again (he just assumed they were 1/0).
So now I can just set a new 400a panel right in. Is there a limit on how far away the 200 load center can be? (other than the resistence factor?)

Straightedge

Your pictures must be stored on a web server. If you don't have web space available send the pictures to bill and he will post them for you.

Curt

aldav53,

There is no distance limitation between the 200 amp breaker and your sub panel.

Curt

Adlav53,

Caselec, said that the 4/0 aluminum is only for 200-amp services. The 400-amp service will need 350 MCM aluminum. This will cause you to run bigger PVC conduit from the transformer.

The POCO architect should of realized that. Are you sure that he understands clearly that you are planning on upgrading from 200-amp service to 400-amp service?

You can put the remote 200-amp panel on the other side of the house or lot for that matter. It does not matter, just more 2/0 / 3 romex for you to buy.

[img]http://www.dale-electric.com/images/4%2D0%20ser%2D4wre%2Dal%2Ejpg[/img]

Tev

In the code book 4/0 is rated a lot less than 400 amps. Maybe the power co has different standards?

I will need 3 or 4/0 just for the 200 amp panel. Will check with Po Co again on that.

Checked with the Power Co on the 4/0 and they say it is good for a 400a service, they have their own standards. Not sure how the Power Co rates their wire?
I will need at least 3/0 (good for 214 amps) or 4/0 (253 amps) for the 200 amp sub panel.
Looks like a 2" emt run through the garage to the back of the house.

In Phoenix at least 1/0 AL for 200A and 4/0 AL for 400A from the POCO is normal. We also can't use EUSERC in Phoenix for one reason or another. Seems APS and SRP like to do things differently here. Make sure you get a 400A service specifically for your utility company. They both use different style meter sockets on there 400A services. Wonder how Tucson is since they have a different POCO?

Well the 400 amp panel passed inspec and is up and running. Although I did have to add another 8 circuit subpanel because there are only 30 spaces in the main 400 amp (40 in the original 200a). So I have a 400a with a 200a sub on the other side of the house, then a 100a right next to the 400a.

Aldav,

Hey, good job!!

I have a question. Did SRP have to pull in bigger feeder wires? If so, did they use the same conduit?

Thanks,

Tev

No, SRP did not have to pull in bigger feeders, they said 4/0 was big enough for 400 amps.

US utilities typically apply demand/diversity factors for single services, where that is a little unusual in NEC-land. Part of their rationale is that they use a shorter list of standardized ‘cookie-cutter’ construction materials, and can replace something of theirs that’s broken at 3AM if they ”need” to.

Some ‘engineering justification’ by utilities for small service-lateral conductors is not NEC 310-16 cable-insulation thermal problems contactors allow for, but 1.) Calculations are made so the customer won’t have a voltage-drop problem, and 2.) Conductor size is assigned by us to limit fault current at customer equipment.

Over time, if you get to know their estimators, you can deal with them a little. An argument I got into with a large utility a couple of decades ago was over their insistance on me installing 2-bolt ½-inch compression lugs in a 400-amp CT section…for 1/0 AWG AL. Their attitude can be: “Do it our way or no electric service. Case Closed—End Of Discussion.”




[This message has been edited by Bjarney (edited 10-05-2003).]