sub-panel / feeder question for residence

[zeb7k]

This is for a yet-to-be-built house. I want to have a 200A electrical service that goes underground into the basement of a two- story house. For reasons I wont get into here I want a sub-panel (non service-rated panel) for each floor. At my option all the sub panels will have their own breaker. The 1st floor requires a 36A feeder and the second floor requires a 168A feeder. Besides controling all sub- panels from their respective breakers I want to be able to disconnect each sub-panel via main basement panel.

I thought I would be able to treat the feeders almost like branch circuits running from the basement panel: a 40A double pole breaker for the 1st floor and a 175A double pole breaker for the 2nd floor. The problem is they don't seem to make double pole branch breakers larger than 125A --at least that's what my SquareD catalog says.

What is normally done in this case?

--zeb

[RBM]

How about a 200 amp disconnect feeding into a trough. Tap both a 200 amp feeder for the second floor panel and the 40 amp feeder for the first floor panel off the main 200 amp feeder in the trough. You can use a panel with

200 amp disconnect for the second floor and one with 40 amp disconnect for the first. Keep in mind as both panels are subs, they require four wire feeders

[Steve Barker]

Nothing is "normally" done in this case, because it is not a "normal" case. Why do you wish to complicate your electrical system like this?

[zeb7k]

Those are the reasons I mentioned I did not want to get into, but here it goes. This is an all concrete building with all wiring in conduit. Every switch controlled fixture is controlled by a low- voltage remote control box located located next to the sub panel for that floor. Remote control means a home run of #14 for each control point. I'm finding it easier to divide the wiring by floor rather then running hundreds of #14's thru a big ass pipe from a central remote control panel in the basement. The remote boxes for each floor are already quite large, combining them into a single one would be prohibitive. Rather I want to run feeders to each sub panel and have a floor-specific remote control box next to each sub panel.

--zeb

[zeb7k]

I would have my main panel in the basement.

[John Grabowski]

In addition you may not be able to find a 200 amp single phase panel that is rated for a 175 amp branch circuit. You didn't mention if you were planning to have a main or subpanel in the basement.

What you can do is split the service as soon as it enters the building. Bring your underground conduit directly into a trough. Install a 200 main panel above or below the trough and a 200 (Or 225) amp main breaker enclosure next to it. You splice your wires in the trough. Install a 175 amp CB in the breaker enclosure and run your subpanel feed from that. The other subpanel can be fed from the main panel. I can't remember if a main circuit breaker is required outside after the meter for this type of installation or not. I'm guessing not. Check your code book and with your power company.

John Grabowski

[John Grabowski]

Roy, wouldn't the 40 amp line be limited to 10' in this installation as you described? I'll have to check my book.

[RBM]

Now, I see. He would need a disconnect at the trough in the basement if the panel had to go on the first floor.

[zeb7k]

Could I just use a 200A basement panel with feed-thru lugs and use the lugs for the 175A feeder?

[RBM]

Not unless you run them into a disconnect with 175 amp breaker. Why not just run a 200 amp line to the second floor?

[John Grabowski]

Wow! That sounds like a lot of extra labor. It is never fun troubleshooting these systems, because of the dual wiring. It always takes more time to find out if the problem is low voltage or line voltage.

Have you considered an X-10 type system. There are several manufacturers including Leviton which makes the Decora Home Controls (

. With these systems you can wire the house normally and just install a switch module instead of a switch. You would just need to have a neutral at the switch location. Your lights could be controlled by computer, by central command boxes, by a remote control, or by the switch module and reprogramming is very easy. You can also have dimmers. This technology has replaced (I thought) the 50's style relay system for homes and has been around for about 30 years.

[zeb7k]

Now that you mention it I will have to go back to my notes to find out why I choose the relay controlled system I described. I like the "switch density" e.g. being able to have a dozen or so pushbutton switches in a 1-gang wall plate. I liked not having to rely on sophisticated electronics that can't be fixed, then again I doubt I could fix a relay. I like the latching feature of the relays I'm using. They remain latched in their on or off state even if the power goes off. The separate conduit for low voltage runs is definitely a minus. I will reconsider the X10 offerings.

As to my original post, thanks to everyone. At least you got me thinking. My 168A feeder number contained a lot of expansion capacity so I was able to revise it down to 150A and still have respectable expansion. Given this, I think (you tell me) I could use a Square D QO2150 breaker to feed that feeder from the main basement

200A QO panel. The current Square D catalog has no cautions against this, unlike my catalog from 2001.

--zeb

[John Grabowski]

You can have that with X-10 without a bunch of extra wires.

I liked not having to rely on

The technology has evolved well over the years and is very reliable. Also different manufacturers devices are usually interchangable. I do recommend a good grounding system to protect the electronics from lightning strikes.

I like the latching feature of the relays I'm using. They remain latched in their on or off state even if the power

I think that the X-10 relays stay latched during power failures.

The separate conduit for low voltage runs is definitely a

[Mark Lloyd]

Those that use relays do. Those that use triacs (lamp modules) default to off after a power failure.

Also X10 devices can be very unreliable. for one reason, it's an old protocol with very limited error checking.

There are some newer things (like Insteon?) that may be better, although I don't have any experience with them.