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Old 03-12-2009, 12:38 PM   #1
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400 Amp Upgrade / Transfer Switch


I am getting ready to do my main panel upgrade. I have decided to upgrade to 400 (320) amp service at the same time.

My reasoning for doing the upgrade is based on the following:

Primary Heat Source is a 5 ton HP.
Secondary Heat source is 20KW resistence heat.
55 Gallon Electric Water Heater
Electric Range
Electric Microwave/Oven

I also just finished a 40x68 pole barn of which part will be a workshop.
My house is 3500 sq ft, plus a 1500 unfinished basement.

In doing all this work, we'll be replacing the old 1970s 200 amp panel with a new one, and setting a second one beside it to handle the 100 amp sub panel in the basement dedicated to the HP and 20kw heat. This second 200 amp panel will also handle the 100 amp service to the workshop.

My question is two fold.

Upgrading to 400 amp isn't an overkill right?

Second, someday I plan on getting a wholehouse generator to run the HP and some lights.

I think I should put a transfer switch in now, as we have to replace the meter socket, the underground drop from the transformer, etc.

When looking at transfer switches, 400 amp manual switches appear to costly. Do I just pick one of the 200 amp panels and put a 200 amp switch in?

Should I put a manual disconnect option at the meter to shut service off outside?

---------

The meter is on the back of the garage and faces the back patio area where we often hang out. I don't want this wall to become full of boxes and conduit as it will detract from the back patio area that has the hottub, etc.
-------------

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Old 03-12-2009, 01:47 PM   #2
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400 Amp Upgrade / Transfer Switch


Since most 400/320A residential services are simply two 200A panels I would choose the circuit you want to transfer and keep them in one panel and install a 200A transfer switch for just that one panel.

Keep in mind, I don't know what code your area is under, but there is a (stupid) new 2008 NEC change that states an automatically transferred load, the generator must be able to handle the WHOLE load.
So if you do just one panel automatically, and the demand load on that panel is 150A @ 240v then the generator you get must be at least 35kW. That's 35,000 watts.
Consider that when thinking about going with a full 400A transfer switch.

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Old 03-12-2009, 02:06 PM   #3
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400 Amp Upgrade / Transfer Switch


Thanks for the response.

Perhaps I'll skip the whole house transfer switch, and when it comes time to do that part of it, I'll use an indoor transfer switch and move the services I want to protect to that transfer switch with its own internal breakers.
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Old 03-12-2009, 04:50 PM   #4
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400 Amp Upgrade / Transfer Switch


Not sure what brand generator your thinking of going with but,
Generac has a "genready" load center that is a 200 amp panel that has the transfer mechanism installed.

It is a Seimens load center, comes in basic and advanced. The basic just doesn't have the transfer mechanism installed yet is a little less expensive.

Just an idea.
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Old 03-12-2009, 06:04 PM   #5
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400 Amp Upgrade / Transfer Switch


An option also with the 08 requirement with the auto switch is, you may have 20KW heat but I'd be sure they're staged. You could install an interlock so, when the generator is running, it will lock out 5-10 kw of strips. You wouldn't have full heat capabilities but, you'd have some heat and you don't always lose power in the winter.

I do this a lot with customers because, as Petey stated, your looking at a huge generator which most can't afford or justify the expense.
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Old 05-18-2009, 01:28 PM   #6
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400 Amp Upgrade / Transfer Switch


I've decided to not go with the whole house transfer switch for now. Since I need to get this project completed so I can run electric to my barn.

I have located a local electrician that was laid off and is willing to help for a fee. Before I have him come out, I plan on doing as much of the preliminary work as I can.

I have attached a sketch of my plan.

My question has to do with the 400 amp dual lug meter socket.

I bought it from a guy that was going to use it, but never did. Yet he popped out the bottom two holes and one on the back of the meter socket.

I only need one bottom one (ground feed from utility) and the one in the back of the box to get inside of the house. What can I do about the 2nd bottom hole?

Can I use SE cable between the meter socket to each 200 amp panel that sit next to each other? If so, do I have to run them thru separate holes into the house or can they both go through the rear hole of the meter socket box?

Will code permit me to then drill a hole through the 2x4 separating the entrance hole from the meter socket to the second 200 amp panel or do I need to bring the SE cable into the joist void that each panel is in?
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Old 05-18-2009, 03:45 PM   #7
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400 Amp Upgrade / Transfer Switch


Quote:
Originally Posted by AndrewF View Post
I have located a local electrician that was laid off and is willing to help for a fee. Before I have him come out, I plan on doing as much of the preliminary work as I can.
All I can say is be careful.



Quote:
Originally Posted by AndrewF View Post
I only need one bottom one (ground feed from utility) and the one in the back of the box to get inside of the house. What can I do about the 2nd bottom hole?
A weatherproof knockout seal.



Quote:
Originally Posted by AndrewF View Post
Can I use SE cable between the meter socket to each 200 amp panel that sit next to each other?
Yes.


Quote:
Originally Posted by AndrewF View Post
If so, do I have to run them thru separate holes into the house or can they both go through the rear hole of the meter socket box?
Separate holes and connectors.


Quote:
Originally Posted by AndrewF View Post
Will code permit me to then drill a hole through the 2x4 separating the entrance hole from the meter socket to the second 200 amp panel or do I need to bring the SE cable into the joist void that each panel is in?
Any hole you drill for 200A SE cable will be too big for a 2x4.
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Old 05-18-2009, 04:27 PM   #8
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400 Amp Upgrade / Transfer Switch


Quote:
Originally Posted by AndrewF View Post
Upgrading to 400 amp isn't an overkill right?
Primary Heat Source is a 5 ton HP.
~6kW, 25A
Secondary Heat source is 20KW resistence heat.
83A
55 Gallon Electric Water Heater
18A or 36A
Electric Range
50A?
Electric Microwave/Oven
50A?
Other
http://www.wholesalesolar.com/pdf.fo...ower-table.pdf

200A + 100A gives you less than 56A of headroom, 400A gives you 100A on top of that.

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Old 05-18-2009, 09:34 PM   #9
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400 Amp Upgrade / Transfer Switch


Quote:
Originally Posted by Speedy Petey View Post
A

Separate holes and connectors.

Any hole you drill for 200A SE cable will be too big for a 2x4.
Ok, so I'll need to drill two 3.5" holes through the brick to get to each panel from outside. Not a biggie, I just wanted to see if I could do a really clean install by running both through a single hole in the back of the meter socket.

This setup is on the back of the house right near where our patio is, so anything I can do to keep a clean simple install was my goal.

I guess I could try to stagger the panel over a 2x4 and then run a hole from the meter socket on each side of the 2x4 to access each panel.

Also, when the SE cable comes into the wall cavity, I was going to leave it exposed in the wall cavity and then come into the bottom of the 200 amp panels utilizing a "compression" fitting. There is no need to run pvc conduit through the wall and then try to make the right 90 degree turn into the bottom of the panel, right?

----------

As for the laid off electrician, he was registered in this county up until a few years ago. (He lives in a different county).

Since I am only paying for his time, I want to ensure I am getting all the right components and doing the job "right" or the best way versus some cobbled up way that might still pass county inspection.
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Old 05-18-2009, 10:04 PM   #10
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400 Amp Upgrade / Transfer Switch


Quote:
Originally Posted by AndrewF View Post
Ok, so I'll need to drill two 3.5" holes through the brick to get to each panel from outside. Not a biggie, I just wanted to see if I could do a really clean install by running both through a single hole in the back of the meter socket.
You shouldn't need a hole that big. Just big enough for the cable. You can chip away the wall behind the box to account for the connector.



Quote:
Originally Posted by AndrewF View Post
Also, when the SE cable comes into the wall cavity, I was going to leave it exposed in the wall cavity and then come into the bottom of the 200 amp panels utilizing a "compression" fitting. There is no need to run pvc conduit through the wall and then try to make the right 90 degree turn into the bottom of the panel, right?
As long as the cable is not directly subject to damage you are fine w/o PVC.
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Old 06-02-2009, 09:02 PM   #11
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400 Amp Upgrade / Transfer Switch


Quote:
Originally Posted by Speedy Petey View Post

Separate holes and connectors.


Any hole you drill for 200A SE cable will be too big for a 2x4.
Speedy,

I checked and the existing 200 amp SE cable is ran thru a hole in the 2x4 from the adjacent space.

Do the 2008 NEC regulations state this is forbidden or is it just bad practice?

The meter socket I bought, has a 3" hole drilled in the back of it, right where I would need to stradle the location of the 2x4....so if I can move the MS one direction, I can then use the 3" hole and drill only one through the brick wall.
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Old 06-02-2009, 10:29 PM   #12
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400 Amp Upgrade / Transfer Switch


Keep in mind, I don't know what code your area is under, but there is a (stupid) new 2008 NEC change that states an automatically transferred load, the generator must be able to handle the WHOLE load.


This isn't a new code, its always been the case, electricians have just ignored it, so they reworded it to really enforce it.
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Old 06-02-2009, 10:56 PM   #13
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400 Amp Upgrade / Transfer Switch


Thanks...note. I have scrapped the whole transfer switch plan.

Just am upgrading to 400 amp service.
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Old 06-03-2009, 04:42 AM   #14
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400 Amp Upgrade / Transfer Switch


Here is an idea: Stop thinking you have to use type "SE" cable. That stuff is bad news, as far as the Code is concerned. The new Code has derated type SE cable now to the point that it will be impractical to use it in most installations.

Instead, install some PVC nipples directly from the back of the meter box into the backs of the panels, and then use some THWN copper lines to connect your panels. Or at least some XHHW Aluminum wires, if you can't stomach the cost of the copper. But there is so little copper required, the additional cost won't be much of a factor.

Here is your drawing, with the suggested revisions:
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Old 06-03-2009, 04:49 AM   #15
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400 Amp Upgrade / Transfer Switch


Now, as to that transfer switch. It will be far easier and cheaper to simply install a generator interlock kit in one of the new panels. Will you be using Square D panels there? Those interlock kits can be installed at any time down the road, and don't have to be done right now.

To deal with that 3" hole in the back, just buy a blank octagon or 1900 blank cover, and fasten it over the hole, using small truss type TEK screws or pop-rivets. Same thing for that hole in the bottom of the meter box. You don't need a "weatherproof" blank-off on the bottom of the enclosure, since those knockouts were not weatherproof in the first place.

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