Per code, can one 200 amp main panel feed two 200 amp sub panels?
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Do you mean have a 200 A main panel and have two 200 A breakers each feeding it's own 200A panel? Not sure why you would do that? If your load is that high on each sub pannel to require a 200A sub you need a larger service on the main.
Or do you mean using 2 200A panels with mains as sub panels but running them off smaller breakers say 70 A each from the main pannel and using the main 200A breaker on the sub pannel as a local disconnect? Inspectors here in BC let you do this.
It really comes down to your load calculation. Have your sub panels sized according to thier load.
have a good one
The concept I am considering is for a new design with 400 amp meter base feeding two 200 amp main panels in a garage / shop area. This is the best location for the meter and to connect service.
One of the 200 amp panels will feed the garage and shop. The other would feed the subpanels in the house.
I would like to have one subpanel for each floor of the house. This is where I would like to connect the two subpanels in the house to the one main panel in the garage / shop.
The walk-out basement will have the heat pump and water heater. The main floor of the house will have the kitchen, office, and master bath. There is a utility room planned for each floor.
My preference would be to wire the sub panels through the bus bars of the main panel.
My current house has something similar. An inside 200 amp sub panel is wired to the bus bars of an outside 200 amp main panel, which is wired directly to the meter base.
As he said, it comes done to load calculation; e.g., you can't run two 200A feeders out of a 200A main panel. If the ampacity of the feeders are smaller, OK, then are the subpanels they serve overloaded?
From a load calculation point of view, I'm not sure that it does make sense.
As long as all of the wiring is correctly sized for the breaker that it is attached to, I don't think there is a limit to how many circuits you can have installed.
I wasn't planning on adding a 200 amp breaker to the panel, just feeding the sub panel directly off the bus bars of the main panel - which are protected by the 200 amp main breaker.
Have you done load calculations? It is the best way to determine how big your sub panels, main and service needs to be.
Can you provide us some details of what will be served on each panel. As an example my house has a 200Amp main panel it serves 700sq' garage (extras to account for 30A 220 plug and a built in Vac), Electric dryer, Electric Range, 1/2 of the 2200sq' of living space on the main floor lights/plugs and 1 15A 220 warmfloor on the deck. The walkout basement has a 50A sub it serves lighting & plugs only for the 1850sq' basement and 1/2 the upstairs. The house uses a natural gas boiler.
Sounds like you may have some good size heating/cooling loads?
Brad
The panels are sized more for the number of available circuits than for the load. My understanding is that a 300 amp service is as expensive as a 400 amp or nearly so.The 200 amp panel for the garage shop is mostly for the 1,500 sq. ft. wood shop / garage with it's tools, and a heat pump for heating and cooling. Tools include built in dust collector, air compressor, table saw, and lots of expected growth.The 200 amp panel for the 2,700 sq. ft. house is for the 5 ton heat pump, electric water heater, and growth. Gas is not an option, propane costs more than the heat pump in our area.The useage is not expected to be anywhere near that high. I just really hate running out of places to add another circuit breaker.
Sure, why not?You said that you have done it before, so why the question?But to clarify it what you are talking about is two main panels in the shop area. One would be for the shop it'self.The other would be only used as a disconect to feed the house. It could be feed by tapping the bus bar. It would run to a sub-panel on one flooor and inturn that sub-panel would be tapped to feed a sub-panel on the other floor.I am really not sure what is available for panels, but I am under the impression that panels with feed through connections can only support one set of wires so that it would have to be daisy chainged as I mentioned above. The disadvantage of that is that if the sub-panel as a main breaker that it will kill the downstream panel also.And I don't think that it the best use of resources.First I don't see any advantage in have a panel per floor. I would look at where the loads are. You might have a panel on the east end and one on the west end for example.And where is the heatpump and air handler with backup heat strips in relation to the main panel. You might want to run those directly to the main panel (and after looking at all of the loads it might be to the shop panel). Realisticly unless you are into heavy duty welding you will never see more than about 40 amps demand for a one person shop (plus heating/cooling).Then maybe a 150 amps to the panel that serves the stove and other kitchen circuits (and whatever else is in that general area) and a 100 amps to panel to serve the othr part of the house.
You really need to do a load calculation I have a 200amp service but I really don't need it I'm well over double actual load. Here's a Word copy of the one I submitted for a permit to give you an idea. I did miss out a couple things at that time but I also included things I didn't install. I hope it attaches Ok.
My panels are spaced NE and SW corners of the house. Up down is easy. 40/80 panels are common so don't worry about running out of breaker space it's the service conductor that will hurt running 50+' on a 200amp sub panel yikes $$$$. I would however encourage you to run a couple vacant 2"or 3" conduit from attic to basement or even Garage to sub for future unexpected large loads.
I assumed that you addressed this to me just because I had posted the last message, but it ain't I that is building this house.But you have made a lot of assumptions that are not true."40/80 panels are common so don't worry about running out of breaker space"In the US panels are limited to 42 poles.And the load calculations are much different.You have to account for kitchen and laundry ciruit (4500 watts), and the dryer is 5000 watts, water heater 4500. Then demand factors come later.http://www.codecheck.com/images/CCWet02big.jpgAnd the biggies the two heat pumps and they probably have backup resistive heat strips.
Good evening EH!
It's all about perspective. I'm up here in BC Canada and the points are true. That was the reason I pointed out call your inspector initially. A load calculation is required on this job for the main service and its subs to balance the cost/bennefit. The method varies but if you run a house on either load calculation its +-10%. What I posted was just an example I had handy.
I lost my point with the 40/80 subpanel(I do that sometimes) it was that amperage rating is not tied to available breaker openings or are they in the US?
I must agree the electric heating/air with coils will throw this particular calc way up. But how much and on which panels?
Have a good evening or morning I guess it depends on your perspective ;-)
Two heat pumps with backup resistive heat strips.
Two laundry rooms each with a clothes dryer.
The water heater is rated for 9,000 watts.
I am trying to avoid the half size and dual breakers if I can. The bottom floor (walk out basement) will be all cement floors, so I want to go with GFI breakers for all outlets (or at least those that don't requre the arc fault). In the shop, many of the tools will have their own dedicated 220 volt breaker. I want GFI breakers for all the 120 volt outlets in the shop. Two GFI breakers for the counter top outlets in the kitchen. Two GFI breakers for the master bathroom outlets. Seperate GFI breaker for whirlpool tub. Three more GFI breakers for the other two and a half baths. Two more GFI breakers for outdoor outlets. It all requires lots of space in the panels.
The subpanel for the upper floor and the one for the bottom floor also end up at the opposite ends of the house.
This is a case of needing to wire for a lot more capacity than I will ever use. I may disable the resistive heat strips in the shop heat pump, but the breaker still needs to be there. For the few hours a year of winter that we normally have, I can live with 50 degree temperatures in the shop. The water tank is extra large (85 gallon) because for about 10 months out of the year, all of the hot water will heated by a heat pump water heater which has a slow recovery rate- and which needs its own breaker.
> First I don't see any advantage in have a panel per floor.
I like doing it that way. You don't have to climb stairs in the dark if you trip a breaker. You don't have to climb stairs in order to turn a breaker off and back on to work on something. Stuff from the upstairs box runs mostly thru the attic, and from the downstairs box mostly thru the crawl space.
-- J.S.
", you can't run two 200A feeders out of a 200A main panel."Why NOT?
Why NOT?
Well, I was assuming the load calculations for both of the two subpanels justify the use of 200A feeders; you usually don't run fat expensive wires like that if you don't have to. In that case the calculation for the Service is gonna be over 200A.
Note I said 'feeders' and not 'subpanels'; common panels with lotsa breaker spaces are rated for 200A, and if you need/want the spaces the sub itself will be rated for 200A.
I was under the impression that he was want to use panels with "feed through" (not sure what the term is) where the bus bars are tapped to feed another panel.In that case it has to 200 amp feeders.But I agree, and said as much in my response to him, that it might not be the most reasonable approach.
In that case I would check with your local inspector. 400 service here is clasified as industrial & not residential.
Make sure you save up some money for your supply conductors for those panels. With the price of copper these days it might be a bit scary.
Sorry my help is limited
There's no safety reason (though there may be some weird code prohibition) to not have two 200A breakers feeding the two panels, though one would be hard pressed to find 200A non-main breakers to fit a residential panel.It's also legal, under certain circumstances, to have a fused/breakered disconnect at the service entrance (with only one breaker), feeding two separate panels, with no other "panel" in-between.And it's certainly legal to use multiple 200A panels (just to get the slots) fed with smaller breakers off another panel, though it would be a good idea to reduce the main breaker in the 200A panel to something not much greater than the feeding breaker.But generally, for a complex setup like this you need a code lawyer -- someone who knows how to read the fine print and file appeals to the great Inspector General.
If Tyranny and Oppression come to this land, it will be in the guise of fighting a foreign enemy. --James Madison
Did some preliminary load calculations which made some changes in my plans.
Anyway, main power comes in at East end of house at the garage which is on the main level. Most of the power is used at the West end of the house - about 70 feet away and in the walk out basement - heat pump, water heater, central vac and so forth.
So, the current thinking is 400 amp service at garage end. One 200 amp disconnect feeds the sub panel next to all the big power hungry devices in the walk out pasement. Second 200 amp main panel feeds a 100 amp sub panel in the shop, and a 100 amp water-tight sub panel in the breezway between the garage and shop for expansion.
That makes much more sense.
First, the sum of the ratings of the sub-panels has no relation at all to the rating of the main panel. I like the idea of using sub-panels. I try to place them in a place close to the circuits that they serve. For this reason, and considering the number of circuits likely to be used, I usually have one sub for the kitchen itself....it's pretty easy to come up with a dozen circuits in a kitchen these days!