Researching possible configuration my new home for 320A service and need knowledge and assistance from the experts here. I have wire two of my previous houses, but the last one was about 7 years ago and both were 200A and much more simple in size and equipment than our current plans.
Info on new house: 3,100 Sq ft, All electric, 2 A/C units, heat pumps, 2ea double ovens 2 M/Ws, induction cooktop, elect H/W heater, elect dryer, oversized garage which will be sectioned off for partial use as workshop (woodworking equipment, welder, etc), planned Hot tub, planned Pool, and planned guest house with another garage, possible future water well.

Load calc says that I don't need the total 320A, however no one can predict the future and cheaper/easier to install now than retrofit later. We plan on retiring in the house and will spend roughly 40 to 60 years in it, so who knows what we will need 20 years from now and I would rather have the capability and not need it than need the capability and not have it. All surrounding houses are installed with 320A. Also, this is in the country and no permits required, but I do want to follow NEC.

Current plan is to install Milbank 320A meter base per Elect Co. specs and which will be purchased from them. Then install 2 SQ D QO142M200PC panels 35 feet from meter, each with surge protector. Then alternate placement of large draw items between the two panels. Ie, A/C unit #1 on panel 1 and A/C unit #2 on panel 2. I will install 12/2 20A for all standard outlet and 14/2 for all lights. Use GFCI in all required locations and/or AFCI in required locations. Have dedicated circuits for specific equipment such as fridge, 2nd fridge/freezer, comm closet, towel warmer, alarm system, electric fireplaces, etc.

My biggest concern is the prewire for future equipment, SPA, Pool, Guest House, water well.
I plan on installing 60A breaker, run wire and connect to Eaton CH60SPA panel mounted on back of house.
Repeat the same set up for Pool. Pool will have pump, heater, automatic cleaner, lights. Does 60A sound sufficient?
What is the proper set up for guest house? I know it needs to have it's own disco and panel, but since this is another "dwelling", I don't believe I can put 100A breaker in main panel, prewire to a 100A panel mounted to back of house and then run wire from this panel to guest house when built later. The SPA/Pool type set up is not allowed for this correct?

 

Need to get to work but the two panels must be grouped.

 

60A panel for the spa would be ok for pretty much any package spa out there. Note that for both the pool and spa subpanels you need to use conduit and install an insulated green copper ground wire. No cable assemblies allowed here. You will also need to make sure you have a means to bond everything metallic around the pool and spa including the rebar if you're pouring concrete. The bond wire must be #8 solid copper or larger.

60A panel for the pool is probably a little too big if it's just the filter pump, probably too small if you plan on an electric heater. Not sure if electric pool heaters exist, they would be unheard of up here in Michigan. Solar pool heating panels work really well here. I'm sure they'd be exceptional in TX -- consider that to save some $$. You could run a 1-1/2" PVC conduit 18" deep and then you can pull in whatever you need in the future when you size the pool equipment.

The feed to the pool house can be sized based on calculated load, doesn't necessarily have to be 100A. Again, possibly another opportunity to run 1-1/2" pipe then have a lot of flexibility in the future.

 

@pcboss, thanks for the info. I have the proper set up for the dual 200A panels. My main concern is my future equipment prewires.

@ibpooks, good info. I had a brain lapse last night and forgot that my plan is to use gas heater for the pool. Even though 60A is probably too much, is it still ok to install and I may hook up other equipment for pool area such as pool accent lighting, stereo, etc?

Follow-up question for the subpanels, on the pool and spa subpanel, I want to run the cable through the house and install the panels attached to the back of the house on the masonry. Since i need to run these in conduit, should I put the conduit in ground prior to the slab being poured or can I run the conduit up the wall, through the attic and down the back wall and ell into the panel attached to the back?
The only reason I am confused here is that in my last house, we had the builder prewire for a spa and they just put in a 50A breaker in the main panel and then a outdoor metal box with the wires in it. We never bought a spa, so I didn't get a chance to look inside, but this was in city limits and passed inspection. Of course that was 7 years ago, so maybe code changed.

Guest house will possibly be a "mother in-law" house with occupation for aging years. It will have a mini kitchen, a/c unit, mini fridge, etc. Basically a upgraded hotel suite with an attached garage, where I get to store more tools and use for expanded shop. That is why I planned 100A. I do like the idea of 1 1/2" conduit and I always try to install at least 2ea 4" pieces of pipe under driveways and sidewalks for feeding electric and water lines. My biggest question on this though, is it within code to "tap" off one of the 200A panels with 100A breaker, run in conduit to disconnect/panel on back of house and wait until guest house is built to place the final run in conduit? Or do I have to tap off of meter somehow and run line fully outside of main dwelling?

Maybe I am overthinking this, but I always like to prewire as much as possible, since it is more complex and labor intensive after the house is completed. I have installed structured cabling (network, cable, phone, video, cctv, HDMI, surround sound) on 5 houses all before the sheetrock was in place and it is 10 times easier than doing it after, especially if attic access is limited.

 

All your circuits and sub panels will need to come out of your 2) 200A panels.
You can just run the conduit now and pull the wires at a later date.

Will you not have a basement where you can run your cables thru ?
If not I'd go under the pour. Keep your lines as short as possible.

Since your two main panels will be more than 5' from the meter you will need 2) 200A main disconnects near the meter.

 

All ok as long as the receptacles are more than 10' from the rim of the pool and have GFCI protection. Only electrical allowed closer than 10' is for powering the pool equipment and those must be dedicated.

Either way is allowed. Under the slab is better to avoiding other utilities, structural framing and reduce conduit fittings. You only need to be 6" deep when buried under the slab, then 90 up through with schedule 80 PVC in the future panel location.

Yep.

Putting a 100A breaker in the main house panel is the correct way to do it. You can just run a conduit to the edge of the house where the trench to the guest house will go and put a cap on it. No need to have a disconnect on the outside of the house -- the breaker is enough. All that's required is a pull access such as a junction box or LB fitting. You can run the pipe through the house or outside the house. Doesn't matter.

Best thing to do in that case is to run conduits and leave accessible pull points where you think you'll need power. Conduit is cheap and pulling wires through preinstalled pipe is cake compared to running something after construction is done.

 

Thanks guys for the info. Very helpful.
@PJ-No basement, only slab. Here in TX, probably 95%+ of new house are slab only. I am sometimes envious of you guys up north with basements. However, I'm a warm weather guy and you guys can keep that cold up there.
Also, typo on the distance for the panels. that was supposed to be 3/5 feet, meaning 3' and 5' (side by side install with wires coming from the sides-I can't do back to back for the meter due to location). Already discussed with electrical company engineer and he will actually meet me at house when I'm ready to place the panels.

@ibpooks-I'll let pool company and their electricians do all the pool wiring when we get to that point, should be included in the price anyways.

For the spa/pool, I was hoping to be able to just run the 6/3 wire same way as running wire for an A/C unit-60A brkr in main panel, then wire up the inside of 2x4 wall, through the attic, down the inside of 2x4 wall, through masonry and then put a disconnect on the outside wall of the house. But I guess my hopes are killed and I need to install conduit.
Funny how this is allowed for A/C units, but not for spas or pools.

Code changes - that figures. Gov't always knows what is best for us right. GFCIs are good and I understand the need for them, but AFCIs are one of these big debatable areas. From all my research, they only add to electrical cost. Next they will update building code to require fire extinguishers in every room of house. ha ha (sarcastic laugh there as I would not put it past them)

For guest house, conduit under slab would probably be best option as you said. You did say there is no need to have a disconnect on the outside of the house, were you referring to main house or guest house or both. I thought I had read somewhere that each "dwelling" had to have it's own disconnect. Basically for safety and if fire dept shows up, they can kill power quickly without having to figure where feed is coming from. Actually found this:
"Article 225 contains the following requirements: A readily accessible disconnect is required at the remote building, located either outside or nearest the point of entrance inside [225-8]. There shall be no more than six disconnects mounted in a single enclosure, or up to six separate enclosures [230-71]. The disconnects must be grouped and each disconnect must be marked to indicate the load served [110-22 and 230-72]. "

Running extra conduits is always good. If I had my choice and time, I would run at least 2 conduits to each corner of the house. Never know when you will want to install electrical for landscape lighting, driveway lighting, a fountain, pond, etc, etc.

 

Interesting,by the way that article reads it does seem that a disconnect would be required,shouldn't create a problem just mount a subpanel inside with a main breaker.
Geo

 

For pools and spas it has to do with a bare ground wire. A solid insulated ground in conduit is required for pool & spa just to make sure it doesn't get broken, corroded, etc. Your nervous system can get disoriented/confused and lead to drowning if even a very low voltage is in the water so maintaining a good ground is very important.

Yes, but the main breaker(s) in that building's panel count as the disconnect. You don't need an additional one. I suppose your local code might require an exterior disconnect, but it is not a general requirement.

Good idea. Grab a roll of 3/4" ENT (smurf tube) conduit and layout out a couple runs under your slab before the concrete guys get there. For about $100 you could get a pair of conduits to every corner of the house. Stub up through with regular PVC fittings which can glue right to the ENT.

 

Sorry, this is still a little confusing for me and I want to be sure I get it right. I thought 6/3 w/uninsulated ground was allowed to be ran interior of house to an attached disconnect. Then I would be required to run 6/3 with insulated ground for final run to the SPA. Mainly the insulation on the ground protects from corrosion.

If not, then I would need to buy 4 different 6awg THNN wires, preferable in Red, Black, White and Green and run them in conduit to the disconnect?

 

Thankfully, the government has nothing to do with the NEC, but local government has the option to add more requirements or delete requirements. I see requirements amended out of the code, but rarely have I seen more requirements added except in places like New York.

If the spa is outdoors you can't use 6-3 NM-B cable anyway and UF cable would be very difficult to pull in conduit. I would use 6-3 MC cable from the 200 amp panel to a disconnect on the outside of the house (that satisfies insulated ground requirement) and then use PVC conduit with separate THHN/THWN conductors; 3 #6s and 1 #10 ground.