400A new home, configuration options/suggestions

[kwired]

I agree, YOUR advice to me ought to end because you are just plain rude. There is always that one guy that has nothing better to do than pick apart somebody else's post looking for a way to criticize......

I have no intention of running a tankless water heater with a generator, didn't YOU catch the part where I said "power only the HWH for 45 minutes to fill the TANK". (regular water heater <30 amps) I will not be powering ANY of the big loads on that list with the generator.

In my current home, the only loads I need to run simultaneously are are the fridge/freezers, well pump, ceiling fans. I get by just fine most of the time with my 3000W Yamaha inverter, which will run quietly all night long on 3 gallons of gas. Occasionally, I will need to power a SINGLE 220V 30A load briefly, such as a TANKED water heater OR a boat lift OR a clothes dryer. When I need to do that I disconnect the Yamaha and connect a 7500W Generac for the duration of the need. It is very loud and guzzles gas. Seems like a hassle, but gasoline is very difficult to get after a storm, propane....impossible. I've had to go two weeks without refueling, so a "smallish" is not a cost cutting measure, it is a necessity. My neighbor was bragging about his 25kW whole house generator setup...till he ran out of propane a couple days into the first storm.

Sounds like an interlock kit on one 200A panel may be the best solution. I don't like the generator subpanel I have now because sometimes the one receptacle I really need that one time isn't on that panel, and you can't add everything to it.

I was thinking just reading your OP that if the equipment you listed there was all electric equipment - there is a possibility that your 400 amp supply might be a little undersized - depending on details that were not provided. But even if not undersized, you may find you need to transfer both 200 amp panels (if that is the route you choose to go) or you may miss some loads you want to be able to run on standby power. You have enough bigger load items that may not be "critical loads" but seem to have enough of them that they may be too much for a single 200 amp feeder to handle and they would need to be split between both 200 amp branches.

Again this based on not knowing how many watts of instantaneous water heating there is, 7 tons of heat pumps helps some with general load, but we don't know how easy it will be to start those units with a smaller generator without more information or if there is electric back up heat present, how many cooking appliances there are and what size are they (you mentioned both ranges and wall ovens), how large are well pumps (you said there were 2), size of pool pump and possible heater (assume heat pump type heater would be most efficient, not sure if that is what is desired though or what capacity would be for any heater for that matter), hot tub load can vary depending on unit. I have had homes with less items then you mentioned that have more then 400 amps of service supplied to them, electric heating was main item that pushed them over 400 amps though, and had they gone with instantaneous electric water heating - maybe would have bumped them to more then they do have for capacity. Around here you need to heat fresh groundwater at least 65 - 70 degrees to get 125 degree water, maybe not quite as much capacity is needed where you are, but those heaters are still a big load when they are running.

 

[electrofelon]

I was thinking just reading your OP that if the equipment you listed there was all electric equipment - there is a possibility that your 400 amp supply might be a little undersized - depending on details that were not provided. But even if not undersized, you may find you need to transfer both 200 amp panels (if that is the route you choose to go) or you may miss some loads you want to be able to run on standby power. You have enough bigger load items that may not be "critical loads" but seem to have enough of them that they may be too much for a single 200 amp feeder to handle and they would need to be split between both 200 amp branches.

Again this based on not knowing how many watts of instantaneous water heating there is, 7 tons of heat pumps helps some with general load, but we don't know how easy it will be to start those units with a smaller generator without more information or if there is electric back up heat present, how many cooking appliances there are and what size are they (you mentioned both ranges and wall ovens), how large are well pumps (you said there were 2), size of pool pump and possible heater (assume heat pump type heater would be most efficient, not sure if that is what is desired though or what capacity would be for any heater for that matter), hot tub load can vary depending on unit. I have had homes with less items then you mentioned that have more then 400 amps of service supplied to them, electric heating was main item that pushed them over 400 amps though, and had they gone with instantaneous electric water heating - maybe would have bumped them to more then they do have for capacity. Around here you need to heat fresh groundwater at least 65 - 70 degrees to get 125 degree water, maybe not quite as much capacity is needed where you are, but those heaters are still a big load when they are running.

Valid concern. He could install 3 200 amp panels, two non critical one critical ( or two 200A and one 100) and still have a 400 amp service. That wouldn't cost that much more. Would just have to get some "triple lugs" or do a tap. All comes down to loading of course which we don't know.

 

[mgookin]

It all starts with the load calc.

The OP is about having 2x200A panels.

 

[kwired]

It all starts with the load calc.

The OP is about having 2x200A panels.

Actually OP seemed set on the need for 400 amps of service but then asked if 2x200 amp panels is the way to go.

There are a few options for what one may deem to be a 400 amp service.

1. A main 400 amp overcurrent device, with any number of branch circuits or feeders supplied from it - the load will never exceed what the main 400 amp overcurrent device can hold for.

2. Next most popular option is 2- 200 amp main overcurrent devices, works well as long as there is no single load that exceeds 200 amps, which doesn't normally occur that often in dwellings, but you could have a feeder to some major appliances like the HVAC equipment that maybe needs more then 200 amps but the rest of the home has minimal load - then this don't work out so well.

3. total load calculation per art 220 does not exceed 400 amps - yet you run two to six service disconnecting means that can add up to well over 400 amps but only run common supply conductors with an ampacity not exceeding whatever the calculated load is- this is NEC compliant, and is done more then some may think.

Bottom line is the proper way to determine capacity of any service starts with load calculations and then selecting equipment needed to supply that load. Some have a tendency to select a service capacity first then apply the load to that, and it may work most of the time especially for dwellings but occasionally it will bite you if you don't do the load calculation first. It usually costs less to install 600 amp equipment once then it costs to install 400 amp equipment and then find out you needed more capacity.

 

[electrofelon]

It all starts with the load calc.

The OP is about having 2x200A panels.

Right, just saying - and his EC should know this, that a 400 amp service can have other combinations than 2 200's and their sum can exceed 400

 

[kwired]

Right, just saying - and his EC should know this, that a 400 amp service can have other combinations than 2 200's and their sum can exceed 400

I installed a new service to a school building a couple years ago. (just from memory) We supplied a 800 amp main lug I-Line panel with the following "main breakers" installed -
2 -400 amp breakers, 2-125 amp breakers (there was still room for two more "mains" and would still meet the six disconnect rule).
Paralleled service conductors amounted to 750 for ampacity, total load calculation I can not recall exact number but was between 500 and 600 amps, yet we had 1250 amps of main overcurrent devices installed on these 750 amp service conductors. Was code compliant and passed inspection.

I can think of a few more similar installs - this one was just the most recent and easier to recall some of the details.

 

[Miranda]

Wow, still trying to get the hang of this forum. I posted two duplicate messages I didn't intend to (and spent a lot of time typing out two other messages that disappeared when I hit "submit reply", telling me I was not signed in. So I apologize for posting both too much and not enough! Will try again.

 

[mgookin]

And then POCO has to be able to provide that service demand; sounds like he's rural/ remote somewhat.

 

[kwired]

Wow, still trying to get the hang of this forum. I posted two duplicate messages I didn't intend to (and spent a lot of time typing out two other messages that disappeared when I hit "submit reply", telling me I was not signed in. So I apologize for posting both too much and not enough! Will try again.

One trick for a long post or at least one that takes a little time to compose for whatever reason is to compose it in a separate application like a word processor or even just a text document and then copy and paste into the forum composition window. Then if something goes wrong and you lose it somehow, you just copy and paste again instead of spending a lot of time composing it again.

 

[Miranda]

Thank you for all your responses. I'm sure we will do thorough load calculations once I choose an electrician. The house is still in design phase so I am just trying to get an idea of how the whole electrical plan may come together and how it will work with a generator. I see that there are many ways to divide the loads across two panels.

The house is about 4000 sf in a warm climate. Most comparable homes in the area are built with 200A, but I'm told 400A would be a good idea even if not determined to be necessary. It is all electric except for propane cooktop. No backup heat (strips are installed in heat pumps but never gets cold enough to use them) 7 tons was a max/high guesstimate as are many of the values given, since the house is still in design phase.

The generator is just for light loads (one well pump, fans, fridges), no heating, no cooling, no cooking. Occasionally we will run a larger load separately, for example, before a bath, we will shut off everything else and cut o the 30A breaker for the hot water heater and run it 45 minutes to heat a 40 gal tank of water. Same applies for the clothes dryer, but ONLY if everything else is shut off. This has worked well for us in the past with a portable genset.

Fuel has to last a couple weeks sometimes, so "smallish" is mandatory. Big whole house generators burn too much fuel to keep on hand.

You guys here are exceptional, because you take the time to interract with other pros and share knowledge. That really sets you apart as the professionals that you are. I can't say that the majority of contractors I have worked with actually take the time to determine the client's actual needs or offer options. They just do it "the way we've always done it" and install what is on the truck, or what works best for their bottom line, which is not necessarily in the client's best interests. Some of them are great craftsmen, but crappy communicators. Others are smooth talkers but crappy contractors (these are the ones that come highly recommended by friends and family until 5 years later when everything they did falls apart). At any rate, I have learned that everything goes more smoothly if I educate myself to get a good idea of what I want/need before I sit down with the contractor.

 

[Miranda]

And then POCO has to be able to provide that service demand; sounds like he's rural/ remote somewhat.

Indeed....rural, remote, hot wet and low. The hardest part is finding contractors (all trades) willing to come out here. The funniest part is when they take three weeks to send me a quote that is easily triple what it should be because they really don't want to come back. Why do people do that? If you don't want the job just tell me. No point wasting everybody's time typing up some bogus inflated bid.

 

[electricalist]

If you pay the price they want to do. For that price. If you get bid that high consistantly then the price is the going rate.

 

[Miranda]

And then POCO has to be able to provide that service demand; sounds like he's rural/ remote somewhat.

If you pay the price they want to do. For that price. If you get bid that high consistantly then the price is the going rate.

No, I'm not talking about consistently high bids because of the locale, I'm talking about the guy that makes you wait three weeks then bids 23K when everybody else is around 7K. I could pay the 7K guy 10K and fly him in every day by helicopter for that. What is the point of that? The point is he is booked up and doesn't need the work, but if I'm stupid enough to pay that he'll bump somebody else down the schedule and get right to you. That's not free market economics, that's just wrongness. I wouldn't want to work for someone stupid enough to fall for that. Couldn't sleep at night if I did that to people. And since I'm not that stupid, all he accomplishes is a reputation for being overpriced and/or ripping people off....plus a whole lot of extra miles on his truck for bids that don't bear fruit.

 

[electricalist]

Ok.

 

[readydave8]

No, I'm not talking about consistently high bids because of the locale, I'm talking about the guy that makes you wait three weeks then bids 23K when everybody else is around 7K. I could pay the 7K guy 10K and fly him in every day by helicopter for that. What is the point of that? The point is he is booked up and doesn't need the work, but if I'm stupid enough to pay that he'll bump somebody else down the schedule and get right to you. That's not free market economics, that's just wrongness. I wouldn't want to work for someone stupid enough to fall for that. Couldn't sleep at night if I did that to people. And since I'm not that stupid, all he accomplishes is a reputation for being overpriced and/or ripping people off....plus a whole lot of extra miles on his truck for bids that don't bear fruit.

May have something to do with supply and demand?

 

[kwired]

No, I'm not talking about consistently high bids because of the locale, I'm talking about the guy that makes you wait three weeks then bids 23K when everybody else is around 7K. I could pay the 7K guy 10K and fly him in every day by helicopter for that. What is the point of that? The point is he is booked up and doesn't need the work, but if I'm stupid enough to pay that he'll bump somebody else down the schedule and get right to you. That's not free market economics, that's just wrongness. I wouldn't want to work for someone stupid enough to fall for that. Couldn't sleep at night if I did that to people. And since I'm not that stupid, all he accomplishes is a reputation for being overpriced and/or ripping people off....plus a whole lot of extra miles on his truck for bids that don't bear fruit.

I have been on both ends of this before. If I am lower then everyone else I have to ask myself what did I miss and hope I don't lose my butt on that job. If I am high it may be that I either don't want the job that bad, was busy and didn't have time to give a accurate estimate but gave what I though was still safe enough to help ensure I don't lose if I should get the job, and often times I just don't have complete information on what I will be installing - I then assume worst case and bid accordingly. This is especially true for residential work around here - I never really bid those jobs but do give many high estimates based on relatively incomplete plans -usually all I get is a basic floor plan and never anything that has any significant electrical details whatsoever, also no heating or cooling so you have to guess what you will also need to provide for that.

I often explain some of this to potential customers, some just think you are high and that is fine - I maybe don't want to work for those people anyway, but I also find it is easier to tell them the price will be less then the estimate then to try to ask them for more then what your estimate was.

 

[electricalist]

Kwired that's what I was trying to imply.
Not every one bids high to get over on the customer.
I have yet to hear a for sure equipment requirement, so I'm sure any one looking at bidding it can't give a number that's fair.
Quote it low and they'll hold you to it. Bid it high and you're greedy.

 

[mgookin]

If you're a first-time (and possibly one-time) customer to that EC, he's going to bid you higher. You get market rate once you become a regular customer and pay your bills as agreed.

A large custom home on the waterfront is going to pay more. There are unknowns and unexpecteds and even if you do get paid for change orders, just the notion that it's going to take a lot of time sorting all that out resulting in project delays (and more travel), longer carrying time, etc. brings a premium.

And then there's the philosophy "If he's on the water - he's got money" as my EC buddy used to say 30 years ago when some rich guy wants him to wire a dock for a boatlift & lights.

So you may have a few things going against you which are going to cost you a little more.

Good luck with your project; it sounds like a fun one.