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I’m interested in building a new home. The home has a little over 4,000 sq ft and after doing some circuit layouts for the unfinished basement that I want to finish, I think I’m going to need a circuit panel larger than 200 Amps. Can anyone tell me what the next step up in size is and how much extra it would cost for the builder to put it in.
Thanks and have a Happy New Year.
Thanks,
Dale Berry
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Replies
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Dale,
You can start by chatting with your power company about what they provide. Ours have an upgraded option for home (not commercial) which goes 360A, if memory serves. 200A is pretty common for homes. Have seen new condos with 120A panels and maxed out. Build in the capacity from the start. Much cheaper to have some excess panel capacity.
I toured one custom home up the hill that had two 200A panels. Nice, but then they wired everything they could in 14g Romex. Given the distance from the panels to the top floor and far end ('bout a day's walk), I would have sprung for 12g Romex.
Asours was a club project, we had to bring in two 200A services from the pole to a CT can feeding two 200A RT panels. We also had to provide the two 4/0 UF feeders, the trench, etc. and give them Sked 80 3" PVC 10' up the pole, plus wire. They took it from there. It was a fun job: There are 30 tons of sand down there with 3" below the 24" line, 5" of top cover and backfill. Inspector was impressed.
Have you done your load calculations? What are you planning to run aside from the normal stuff? Are your calculated loads getting near 200A? A shop? If I were doing a shop, I'd have a 240v subpanel run to the shop or garage.
*Hi John, Thanks for responding. I'm planning on putting a wood shop downstairs. I have 3 computers that I want to put on Isolated ground fault circuits, along with a satellite receiver. Exercise equipment, central air, a couple of dedicated microwave circuits, and baseboard heaters on the lowest level for heat. I'm planning on having ceiling fans in several rooms in the house. Based on my load calculations I'm getting real close to 200A, and like you say it's cheaper to have excess panel capacity than not to have it and have to retrograde later. I'm also tempted to have them install two subpanels, it should make the wiring easier and better organized.
*Hi John, Thanks for responding. I'm planning on putting a wood shop downstairs. I have 3 computers that I want to put on Isolated ground fault circuits, along with a satellite receiver. Exercise equipment, central air, a couple of dedicated microwave circuits, and baseboard heaters on the lowest level for heat. I'm planning on having ceiling fans in several rooms in the house. Based on my load calculations I'm getting real close to 200A, and like you say it's cheaper to have excess panel capacity than not to have it and have to retrograde later. I'm also tempted to have them install two subpanels, it should make the wiring easier and better organized.
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Dale,
Don't assume that the total number of circuits you need is the same as your service requirement. Your dedicated computer circuits will probably be an insignificant load. The NEC has formulas for computing total load. You may find that 200 amps is sufficient. Another possibiltiy is to go 3 phase if it is available. You will get three times the power with a single extra wire. Often it is possible to get 3 phase residential service if you have a large single motor requiement.
*I've always used the rule of thumb that amperage need is the greater of one's HVAC draws (usually A/C) plus 60% of all remaining possible requirements. Is this valid?
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Mike,
Thanks for your response. I didn't know about the 3 phase residential service. I'll check into it.
Thanks,
Dale
*Hmmm, what a coincidence(sp?)For a 4000sqft house I would go for 400A residential service. Dont push the limit with 200A cause you'll be sorry in the future. Most houses here in the south that are quite large have 3 or 4 AC units and they are big ones. It will be more expensive but not as expensive as going 200A now and then having to upgrade in the future. glenn
*Thanks Glen, Great advice from someone with a great last name!
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Also I forgot to mention that down here they have 400A 3 phase resedential. It might be worth checkin into. Talk to a power consultant at your electric company. 3 phase service is 3 times as efficient as single phase service. Might be good to run 3 phase AC's. Good luck
glenn
*Dale, You are more likely to need more circuit breaker spaces than you are increased amp capacity in your service , but you know the situation better than I do. When we build homes of this size or larger, we install two 200 amp panels side by side. This is the cheapest way to get what you want because you just feed into the panels from one 400 amp meter tower. The wires coming to the meter tower are larger, but the power company provides them anyway at no additional cost to us. This is a very simple installation and uses materials that are relatively inexpensive and in sizes that are easy to work with.
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I think the dual 200A panels is the best way to go if for no other reason than the shear size of a 400A panel (go look at one before you decide). Plus, you can get more breaker locations with 2.
You may want to consider a sub-panel with a locking door dedicated to your shop; if you have, or plan to have children, it's nice to be able to shut down power to all the tools and lock the panel.
As far as load calculations go, NEC article 220 provides two methods of calculation.
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A couple of thoughts: In the 20's through 40's houses had 30 amp services, then in the 40's and 50's they went to 60 amps. Then 100 amp was typical and currently 200 amps is the normal. Do you see a pattern here? I'd go with two 200 amp panels or a 400 amp one in a medium or large house, if building it for yourself. Within a decade or two you'll be glad you did.
No one's mentioned the advantages of three phase power.
1) 3-phase motors are more efficient (90-94% versus 83-89% for single phase motors),
2) 3-phase motors are less expensive (like $450 for $650 for the same horsepower),
3) you run 40% less copper for the same hp with 3-phase, and
4) sometimes you can get a real deal on a pump, fan, motor, or shop tool because it's 3-phase and no one else can use it.
The downsides include if your utility charges you extra and the a little bit more complicated wiring.
-David
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Glenn -
Where do I have to move to get residential 3 phase.
In Kirkland, WA. we asked and they laughed: No, as if, etc.
J Wells
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Dale;
I installed a 400A Square D panel for a large home (4500 sq ft plus a barn and shop). I don't recall the model for the panel, but they have several. here in California they require a meter base and main breaker accessible from outside. The panel I installed has two 200A main disconnects/breaker. One feeds a set of lugs, and this was wired to a 200A subpanel in the home (laundry room, no flashlites at night) The other 200A breaker feeds a 30 slot panel. This has a 125A for the barn/shop, and 30A to the pool house.
This was a nice clean set up, and it gets the panel back inside where it belongs. I used the SqD QO line breakers, which I prefer, for the interior 200A subpanel. I didn't like the fact that the 400A panel uses the "homeline" garbage.
Regarding 3 phase: here in PG&E country, anybody can order it but you gotta pay to string wires from the last pole with 3 phase. I was told "around $68,000, would I like a more exact quote?" Right.
Regarding "costs to have a builder install": The panel itself was around $800 trade price. This compares to $150-200 for the 200A variety. You also have to figure a little more for the conduit sizes required, and any additional subpanel breakers. It is a more complex installation, and requires special attention by the electrical sub...you'll probably pay 2 to 3 times the material cost difference in labor charges.
G Luck
Adam
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Dave,
Sounds like fun. If you are planning it, you can do it right up front. There is nothing fun about shoes that pinch or undersized service. When I see that the builder has maxed out the panel before the buyer even has a chance, I wonder what other corners got cut.
Get a pair of serious, spacious 200A panels with lots of room for expansion. Should certainly be cheaper that 400A gear. (Price a 400A breaker for fun.) I am partial to Cutler Hammer CH series panels, others' milage Will Assuredly vary.
There is nothing illegal about using more breakers than is the trade practice. Just costs more. One collegue hit a breaker sale and did his custom home with about one breaker per room. Of course, he did it mostly himself so he wasn't paying union scale for the extra wiring work.
Load calcs - not going to turn it all on at once? The calcs have a base load and demand factors to account for the fact that normally one does not have it all on. Going to have to sit down with Article 220 and have fun - or have your electrician do it. 220-30 has a "short form" feeder and service load optional calcs for dwelling units. Try that for a ball park estimate. What is 100% of the nameplate ratings for the AC, water heaters, etc?
SHOPS
I'd certainly run a subpanel to the shop, sized for the future. The suggestion about locking it makes good sense. You can also use lockout switches on the motors. Sounds like the basement will have a lot of stuff: shop, heaters (240?), gym.
Makes good sense to have the computer room outlets on their own circuits. Every time the dishwasher kicks back on as I type, this monitor jiggles. For Y2K, you probably want to float them off a good UPS to counter brownouts.
Are you also planning lots of phone jacks, video, sound, alarm, CCTV, network and other low voltage wiring? It's easy before they rock the walls. After that, not hardly.
Enjoy - and do a few voltage drop calculations for wire size. I know 14g is very popular these days, but...
FWIW - A good book on the topic is Practical Electrical Wiring by Richter and Schwan (McGraw Hill). It covers all sorts of stuff that those home improvement books skip over (643 pages) I have the 16th edition. I suspect there is an update to keep it current with the new code changes
jww
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John: It helps to be in an industrial area, on the way to one (from the electrons' perspective) or near a power line that moving power long distances. Many residental neighbors only have 2 phases (L1 and L2. Or L2 and L3, etc.) So you can get 2 phases of 120-volt and therefore, one phase of 208 volts (2 x 120 volts x sin(120 degrees) by going between them. The utility balances the overall load with very similar draw on each of the phases, but not everyone gets all three phases. -David
*John,Here in Houston you can get 3 phase residential service if you are served by overhead. And no, you dont have to live next to a large factory or a machine shop to get it. But not as likely if it is underground service. The only underground 3 phase is commercial stuff.glenn
*David,*So you can get 2 phases of 120-volt and therefore, one phase of 208 volts (2 x 120 volts x sin(120 degrees) by going between them. The utility balances the overall load with very similar draw on each of the phases, but not everyone gets all three phases.*Two phases of 120V and a hileg (208V), is 3 phase service! It is 4 wire delta. What do you mean by * not everyone gets all 3 phases*? glenn
*Dale,I was not referring to a single 400A panel, but was talking about the service itself. I didnt even know they made a single 400A panel. Install a 400A meterbase, run the load wires to a single fused disconnect, from there you can either go to a trough or run the wires inside to the two 200A panels if you were going to put them in the utility room. If you do install them inside then the disconnect outside is a must. This is mainly for shutting down power during a fire (or for the utility company to releive load so they can disconnect you for nonpayment (just kidding). glenn
*There seems to be a lot of confusion here about 3 phase power. Since I introduced it into this discussion, I'll try to clear it up.Alternating Current. Alternating current switches the directionit travels along a wire. But, it doesn't just switch directions backand forth; that would be square wave current. It goes smoothlyfrom a maximum voltage in one direction to zero to a maximum voltage inthe other direction. The nominal voltage is essentially the averagevoltage in each direction. If you were to graph these voltages youwould have a sine wave.Phase. Since it takes a completed circuit to conduct electricity,there must be another wire carrying it back. If the electricity flowin this wire were the exact opposite of the first wire, i.e. the peaksin one wire matched the valleys in the other direction, we have singlephase. We could say one was 180 degrees away from the other. Now we add a third wire. In order to ballance the system, each setof sine waves must be 1/3 different both the others. This is 3 phasepower. Let's call these three wires L1, L2 and L3. The potentialbetween any one of the three possible pairs of these is the system voltage. Essentially all power generated in this country is 3 phase. Singlephase comes from the distribution system. Electricity is transmittedand distributed at high voltages and only reduced at point of use. 3 phase distribution has all three wires. Single phase has only 2of the three, but there are three possible combinations. L1 and L2,L2 and L3, L1 and L3. In distributing power to single pahse usersthe power company tries achieve ballance among these three pairs.Point of Use. When this electricity gets to where someone wants to use it, it needs to be transformed into voltages that areusable and safe. Let's say the distribution voltage is 12,000.For single phase we have a transformer with two wires wound arounda core, but not connected to each other. Our two 12,000 volt wiresare connected to the ends of one of these wires. This is called theprimary side. If the ratio of the lengths of these wires is 50 to1, the other wire, called the secondary side, will then have a voltageof 12,000/50 = 240. Now if we attach a wire to the middle of thesecondary wire the ratio of the primary to each half of the secondary is100 to 1, so each half of the secondary has 120 volts.3 phase requires three transformers or a transformer with three setsof windings. For the sake of visualization lets look at three transformers. Ignore the primary windings. The secondary windings can be connectedtogether in one of two ways. In a triangle, this is called a delta.Or in a Y.In the delta configuration, the primary secondary ratio is such thatthe voltage between any two corners is 240. A wire is attached tothe middle of one of these so that the voltage between it and the two closestcorners is 120. The voltage between it and the third corner is higher. This is often called the stinger, but forget it.In the Y configuration the primary secondary raito is such that thevoltage between any two arms of the Y is 208. (there are other voltagescommon for commercial uses, such as 480). The voltage between thecenter of the Y and any of the three arms is 120. (120 = 208/ [sq. root3]).So with 3 phase power you have times the power available at the highervoltage, but only 1/3 more available at the lower voltage. You cannottalk about phases of 120, since for all practical purposes it is not phased.
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Hi John,
I've been talking with a dealer in SLC and am planning on putting in a system from IES for all of the things you've mentioned.
I want to future proof the house as much as I can, or at the very least not wire it in the '80s mode and be left out of new technology.
Thanks for the info on Practical Electrical Wiring book. I'll have to check that one out. I've been using the book "The Complete Guide to Home Wiring" by Black and Decker. It seems to be pretty good for a beginner like me. I've never done any wiring before and want to learn as much as possible, so that if I decide to have someone else do the work I'll know enough to ask intelligent questions and have ideas on what I want to do.
Dale
*Thanks for the info. That sounds like what I want to do. I've also thought about adding some external receptacles and just don't want to short change myself. I'm going to have someone else go over my calculations. Thanks,Dale
*Thanks Adam
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I meant not everyone gets 3 equal phases - same voltage and each 120 degrees (1/180 second) phase shifted from each other. I should have been more specific.
I've never tried running a 3-phase motor off of just L1 and L2, can that be done? Seems like you'd have L1 peaking at 0 degrees, L2 at 120 degrees and L2-L1 peaking at 1.732 times higher voltage at 150 degrees. Then no peaks for 210 degrees.
-David
*You can run a three phase motor on one pair. It usually won't start, ie you must spin it manually to start. It won't pull much of a load, but the third terminal will generate the third leg. This is one way to make a single to three phase converter. You need a motor about 1/3 larger than the one you are going to run.
*Mike,What you are referring to is a Delta distribution system. Where it does take all three phases for 3 phase service and two phases for single phase. This is because the type of transformers used and there is not a system neutral. In a Y system it only takes one phase of primary for each transformer and for three phase service it only takes a minimal of 2 phases of primary. In this case the power company would install what is called an open delta bank. This is two transformers with the secondary connected delta. From this you get 120,120,208,240,240,240. The reason it is called "open" is the third side of the triangle isnt there but it still achieves the same thing as if it were a "closed" delta with three transformers. Most systems are Y and very few are delta. Probably because of the extra cost of having more wire and transformers to accomplish the same thing. Also in a Y system you can connect it delta on the primary side of the transformers but with a delta system you can ONLY connect it delta. glenn
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I'm interested in building a new home. The home has a little over 4,000 sq ft and after doing some circuit layouts for the unfinished basement that I want to finish, I think I'm going to need a circuit panel larger than 200 Amps. Can anyone tell me what the next step up in size is and how much extra it would cost for the builder to put it in.
Thanks and have a Happy New Year.
Thanks,
Dale Berry