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Discussion Starter · #1 ·
I have installed a few 200 amp services before, but this 320 amp service will be a first for me. Around here all the meter sockets and first disconnects are outside on a board. I’m installing a 320 amp meter and would like to feed three sub panels from one panel used for all my disconnects. The three sub panels would be a (1) 200 amp for the home, (1) 150 amp for garage and room above and (1) 150 amp for a shop building. Not sure of what I would use for the disconnects. Can I put them all in one panel with the appropriate sized breakers?
 

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Usually you are only allowed to tap the meter twice. The total amps of the 2 mains can be 400 amps. If you can get by with 125 amps to garage and shop, you can put a 200 amp panel with 2- 125 amp breakers. A 2nd 200 amp for the house.
 

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Discussion Starter · #3 ·
Thanks for the feedback. Can I also put breakers in one of the disconnect panels for things like the septic tank pump and well pump or do the need to come off one of the sub panels?
 

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Depending on continuous load to shop and garage, you can come off of the panel feeding garage and shop. I am referring to using a 200 amp main breaker panel, not just a single disconnect
 

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Thanks for the feedback. Can I also put breakers in one of the disconnect panels for things like the septic tank pump and well pump or do the need to come off one of the sub panels?
I think that you two are not understanding each other. What I believe that Marndt is asking can he place all of the disconnects for the 3 feeder supplied panels and 2 branch circuits in a single panel as the Service Disconnecting Means. As a practical matter you can not unless that panel is fitted with a 400 ampere main breaker or supplied through a separate 400 ampere enclosed breaker or fused switch. The code permits the use of up to 6 Service Disconnects grouped in one location for Service Disconnecting Means. Since a 400 ampere main breaker panel would be phenomenally expensive you will want to make use of the 6 disconnecting means rule to install either fused switches or circuit breakers to control the loads you need to supply. The choice between enclosed breakers and fused switches will be based upon which type of Over Current Protective Device (OCPD) will be the most cost effective. The ampacity of an electrical service is not the amperage you would obtain by adding up the ratings of all of the disconnects. It is based on a calculation of the load which they must supply. So far you have mentioned 3 feeders and 2 branch circuits to be supplied by this new service. You will want 5 separately enclosed breakers or fused switches to supply the feeders for each building, and the branch circuits for the sewage lift pump, and the well pump. You can mount all five circuit breaker enclosures or fused switches under a trough into which the service entry conductors have been run from the load terminals of the Meter socket. Those will be tapped for the line sides of four of the disconnects. The branch circuit or feeder disconnect for the well pump is specifically permitted to be located away from the other 4 disconnects in order to make it more likely that the water pump's power will not be cut off by a fire in one of the buildings. For that reason you may want to consider having a meter socket with 2 sets of load terminals. One set of larger conductors will go into a Service Equipment Enclosure type of wiring trough. The other set of Service Entry Conductors will be run from the second set of meter load terminals to the separated disconnect for the water well. That disconnect could be located at the well head itself or on the wall of a well house or at an underground well vault that would also contain the water pressure tank/s. The well house or vault to contain the pressure tanks and the well pump controls would assure that water for first aid fire extinguishment is not made unavailable by the fire that you would want to use the water to extinguish. If the support for the service equipment is located at least 25 feet away from the closest building then you may consider that remote enough from any possibly burning building to have little chance of being disabled by a fire in the nearest structure. From experience gained in 45+ years of volunteer fire suppression service I would suggest 50 feet away from the closest structure.

Your going to have to measure the distance from the service equipment location to each of the 3 buildings. That is based on the garage with an upper room being a separate building from the house and the shop. Please let us know right away if that is not true. Those distances are needed for us to suggest what size wires you will need supply each building.

Is the room over the garage a dwelling? If it will have bathing, cooking, and sleeping facilities then the answer is yes. That only matters if the garage is a separate building. There are online calculators to find the amperage required for a dwelling. Google Dwelling Electrical Service calculator.

Tom Horne
 

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Maybe it is because my POCO's have a list of acceptable equipment posted or maybe it is because I am an electrician. No one can really answer your questions with out knowing what the POCO will accept and a site plan. We have available to us this product.
Several MFG's make products similar to this. You can have breakers installed for disconnects or you can save some money and use the pull out fuses shown.

Do you even know your available fault current?
 

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Discussion Starter · #8 ·
I think that you two are not understanding each other. What I believe that Marndt is asking can he place all of the disconnects for the 3 feeder supplied panels and 2 branch circuits in a single panel as the Service Disconnecting Means. As a practical matter you can not unless that panel is fitted with a 400 ampere main breaker or supplied through a separate 400 ampere enclosed breaker or fused switch. The code permits the use of up to 6 Service Disconnects grouped in one location for Service Disconnecting Means. Since a 400 ampere main breaker panel would be phenomenally expensive you will want to make use of the 6 disconnecting means rule to install either fused switches or circuit breakers to control the loads you need to supply. The choice between enclosed breakers and fused switches will be based upon which type of Over Current Protective Device (OCPD) will be the most cost effective. The ampacity of an electrical service is not the amperage you would obtain by adding up the ratings of all of the disconnects. It is based on a calculation of the load which they must supply. So far you have mentioned 3 feeders and 2 branch circuits to be supplied by this new service. You will want 5 separately enclosed breakers or fused switches to supply the feeders for each building, and the branch circuits for the sewage lift pump, and the well pump. You can mount all five circuit breaker enclosures or fused switches under a trough into which the service entry conductors have been run from the load terminals of the Meter socket. Those will be tapped for the line sides of four of the disconnects. The branch circuit or feeder disconnect for the well pump is specifically permitted to be located away from the other 4 disconnects in order to make it more likely that the water pump's power will not be cut off by a fire in one of the buildings. For that reason you may want to consider having a meter socket with 2 sets of load terminals. One set of larger conductors will go into a Service Equipment Enclosure type of wiring trough. The other set of Service Entry Conductors will be run from the second set of meter load terminals to the separated disconnect for the water well. That disconnect could be located at the well head itself or on the wall of a well house or at an underground well vault that would also contain the water pressure tank/s. The well house or vault to contain the pressure tanks and the well pump controls would assure that water for first aid fire extinguishment is not made unavailable by the fire that you would want to use the water to extinguish. If the support for the service equipment is located at least 25 feet away from the closest building then you may consider that remote enough from any possibly burning building to have little chance of being disabled by a fire in the nearest structure. From experience gained in 45+ years of volunteer fire suppression service I would suggest 50 feet away from the closest structure.

Your going to have to measure the distance from the service equipment location to each of the 3 buildings. That is based on the garage with an upper room being a separate building from the house and the shop. Please let us know right away if that is not true. Those distances are needed for us to suggest what size wires you will need supply each building.

Is the room over the garage a dwelling? If it will have bathing, cooking, and sleeping facilities then the answer is yes. That only matters if the garage is a separate building. There are online calculators to find the amperage required for a dwelling. Google Dwelling Electrical Service calculator.

Tom Horne
Thanks Tom
So the garage with the room over it is attached to the home and is planned to be a dwelling in the future. It’s about 25-30 feet from where the outdoor service will be. The run to where the service will inter the home is another 75 feet away so that’s why I was thinking to add the sub panel directly off the main service outside vs. another sub panel off the 200 amp main breaker panel for the home. I did also find this all on one unit (RC816D400SL) that has the meter socket and 8 spaces for breakers. Would that be a viable alternative to the two panel solution? I have no issues with the two panel solution just wonder if it’s an option. Availability of all these products will likely drive me to the final solution. Also if I understand you correctly I could use 150 amp breakers to the garage and shop as long to the total load isn’t over 200 amps. Is that correct? Same idea as the total amps of all your breakers could add up to more than what the main disconnect is but the total load is under.
Mike
 

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Thanks Tom
So the garage with the room over it is attached to the home and is planned to be a dwelling in the future. It’s about 25-30 feet from where the outdoor service will be. The run to where the service will enter the home is another 75 feet away so that’s why I was thinking to add the sub panel directly off the main service outside vs. another sub panel off the 200 amp main breaker panel for the home. I did also find this all on one unit (RC816D400SL) that has the meter socket and 8 spaces for breakers. Would that be a viable alternative to the two panel solution? I have no issues with the two panel solution just wonder if it’s an option. Availability of all these products will likely drive me to the final solution. Also if I understand you correctly I could use 150 amp breakers to the garage and shop as long to the total load isn’t over 200 amps. Is that correct? Same idea as the total amps of all your breakers could add up to more than what the main disconnect is but the total load is under.
Mike
That is an interesting solution but at ~$1200 you might still benefit by comparing the cost of the all in one with the cost of separate components. That Meter Mains assembly might still come out less costly than the 3 enclosed breakers or switches with a small Main Lug Only (MLO) panel for the water pump and the sewage equipment which would be supplied from a Double Pole Breaker in the factory feed through pane.

Keep in mind that although the feeder to the house can be sized from the residential service conductor size table the feeder to the shop will have to be sized from the standard ampacity tables. 200 amperes to the house can be carried by a single set of 4/0 Aluminum wires, 200 amperes to the shop would have to be run using 250 MCM wires.

What you need to do or have done is a load calculation for each of the 2 buildings. If the calculation for the house, including its garage and overhead room comes out to ~150 Amps or less then I would think a single 200 ampere feeder to the house would be enough. If it begins to creep up closer to the 200 ampere maximum breaker size for this assembly you might want to arrange the loads differently by using different meter mains equipment or go back to my earlier suggestion of installing individually enclosed circuit breakers or fused switches. The location of the well and the sewage equipment may suggest which of the feeders you want to have those 2 loads supplied from.

My instinct would be to have a 200 ampere feeder run to the house supplied through the 2 feed through lugs in the factory installed panel. I would make the the garage panel the main load center, since it's the closest, and run a feeder from the garage panel to the more distant panel in the house. Since that feeder would only have to carry the loads supplied from the more distant panel it might end up being smaller than the 200 ampere feed line from the factory installed feed through lugs of the Meter Mains assembly. Running a feeder separately to each panel will waste both time and money because you would have feeders running in parallel were the one to the panel at the other end of the house could be the only ones for that portion of the supply if it is supplied from the panel in the garage.

The additional reason to have only 1 feeder to the house is that if you have 2 neither of them can be sized from the residential service and feeder wire size table. The wire size for the first feeder segment between the meter mains and the Garage panel would have to be sized 3/0 for 150 Ampere feeder to the garage, that you first asked about, and 250 MCM for the 200 ampere feeder to the other end of the house that you also asked about.

The remaining issue that comes up in my mind is a standby generator connection. The optimum solution for that would be to have an interlock which will fit into the built in panel with the house supplied from a 4 space 150 ampere breaker and the sewage equipment and well pump supplied from a small panel fed by a 2 pole breaker. The other 2 pole breaker would supply the busbars with power from the generator.

When a power interruption occurs you would open the main breaker, move the interlock to the standby power position which latches the main breaker in the open position, connect a portable generator to the interlocked 2 pole tied down breaker, start the generator, close the standby breaker, and use any loads that the generator is capable of powering. Because the houses feeder supply breaker and the small panel with the water pump and sewage equipment would all be on the same set of busbars you would be able to keep the water pump and sewage equipment operating along with selected loads in the house.

Please advise if your property is located within ~5 miles of a fire station that has 24 hour staffing 365 days of the year. If it isn't I'll have additional suggestions on how to wire your water well pump.

Remember all depends on the results of the service load calculation. Without it any further advice would be purely speculative.

Tom Horne
 

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I have installed a few 200 amp services before, but this 320 amp service will be a first for me. Around here all the meter sockets and first disconnects are outside on a board. I’m installing a 320 amp meter and would like to feed three sub panels from one panel used for all my disconnects.
The 150A breakers make it really awkward. I would rethink.

First, it's "CLASS 320" which is a 400A service. This is a nomenclature issue between NEC and power company. For continuous loads NEC applies a 125% derate on a device by device basis. Say you have a 24A EVSE, NEC calls that a 30A load. So by NEC rules, a 400A service is 400A intermittent 320A continuous. The power company calls that 320A. TomaYto tomaHto.

Virtually all 400A services are installed as two 200A main breakers, because those are affordable and 400A main breakers are thousands of dollars. Going with a 400A main breaker and 400A panel and have 200, 150 and 150 amp breakers in that, would be financially suicidal but it's your money.

Generally, separate disconnects are not used. The main breaker doubles as the disconnect, because it's significantly cheaper to do it that way.

Often this is simply two 200A main panels side by side.

However a new product exists, the 400A ranch panel. It contains

  • a meter pan (optional)
  • A 100-200A breaker feeding only lugs (not populated; you install a 100A breaker for 300A service or a 200A breaker for 400A service).
  • Another 200A breaker (supplied) feeding
  • 8 breaker spaces
  • "thru lugs" to bring full 200A to wherever

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So for instance, you might take the 200A top breaker and use its lugs to send all 200A to the house.

Then use the 8-space sub panel to peel off 125A to each of the two buildings you mentioned. Then have 4 free spaces for whatever. Why do I say "125A"? Because you picked 150A out of thin air but it happens to be the most awkward and expensive number you could've picked. 150A branch circuit breakers are rare and very costly, and take 4 breaker spaces.

If you really want 150A to one of the two buildings, I would upgrade that building's feed to 200A and come off the thru lugs at the bottom of the mini-panel. Then keep the 125A breaker for the other building. The feeder will cost more, but not much more at your distances, and it'll altogether eliminate the cost of the 150A breaker. And you'll have 200A at the building instead of 150A. Shared of course.

If you really want 150A to both buildings, then I would see if the vendor will let you replace the 200A lugs at the bottom there with double lugs, and send 200A wire and feeder to both buildings. Same reasoning. If they won't let you use double-lugs then use 3-port Polaris.

I have no issues with the two panel solution just wonder if it’s an option.
Either way, really. I'm kind of partial to separates honestly, so it isn't such a production when you have to replace anything.

They make a simpler 200A version of the Ranch Panel that does not have the meter pan, does have a 200A main, 8 breaker spaces and thru lugs. You could use 2 of those side by side, or simply a discrete 200A breaker only for one side.
 

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Discussion Starter · #11 ·
Thanks, Tom, SeHarper, and others,

This discussion is really helpful!
I did do a couple of online load calculators and I'm running around 160 amps on the house and garage. In regards to amps would probably do it, without much headroom. It's mainly a wood shop and 100 amps would likly do it without much headroom. I have three machines that commonly run at the same time. The three machines consist of two 30 amp breakers and a 40 amp breaker. I know most of the load is at startup and there would have at least a few seconds between them at start-up. I do have plans for a molder that would likely be another 40 amps.
I agree with both of you that the all-in-one solution is nice but expensive and availability might be tough, so the independent panels are likely the way to go and they are available. Tom, in regards to the well after thinking about it some more I will probably need to connect that well to the house panel in the basement where the pressure tank is and I did include the well in my load calculation for the house. You did mention making it ready for a generator, I think that's a great idea and would like to hear more about how that would be done. I am familiar with the panel interlock you mentioned, never installed one, but it looks straightforward. Not sure how to do the rest of the generator setup.

I thought a picture might help with the discussion. Let me know your thoughts on what needs changing. Not sure if I have the wire sizes correct. The POCO wants a #6 bare copper ground wire from the meters to the transformer. Someone mentioned the POCO might have a list of accetable equipment, wouldn't be nice but they don't. My goal is to get this 100% on the design and then add the equipment details and get it over to them for a review. Same with the inspector when I'm ready to pull the permit. Hopefull that will make this go smooth and get it started on the right foot.
Thanks again for all your help!
Mike

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The three machines consist of two 30 amp breakers and a 40 amp breaker. I know most of the load is at startup and there would have at least a few seconds between them at start-up. I do have plans for a molder that would likely be another 40 amps.
You don't do a Load Calculation based on breaker trip. You do it based on nameplate data off the machine or motor. Motors on a dedicated circuit often have oversized breakers, to reduce probability of nuisance trips from motor startup surge. Breakers have 3 jobs: overload protection, short-circuit protection, and bolted-ground-fault protection. Oversizing a breaker destroys overload protection, but that's fine when the motor has its own on-board overload protection (which tends to work better anyway, as it's aware of the internal temperature of the motor).

The momentary startup load of a motor is already factored into panel and system sizing, and you don't need to account for that. If multiple motors starting at once cause a feed breaker trip, add start delays.

Tom, in regards to the well after thinking about it some more I will probably need to connect that well to the house panel in the basement where the pressure tank is and I did include the well in my load calculation for the house.
You only need a signal line to the pressure tank to tell the well when to run. However, if you power the well out of the house, that will make it easier later when you try to add a generator or home battery system and want to power the well. You need to have everything to be powered off a generator coming out of the same panel - can't split a generator to feed 2 panels (without crazy stuff with transformers).

I thought a picture might help with the discussion. Let me know your thoughts on what needs changing.
I have my doubts that the 225A panel will buy you anything. You'd need a meter pan with double lugs where lugs are rated for 225A. They generally expect dual 200A panels, or if the power company is offering 350A ("Class 280?")service, then a 200/150.

That said, I don't see any reason you can't use a 150A main-breaker panel as a sly way to get a 150A breaker there.

If it were me, I'd have the 200A to the house bypass the garage altogether and then have a separate line coming from here to power only the garage. The reason is so you can have the ADU (in-law apartment) and garage on a separate feeder from the house. You'll thank me later if you ever get a tenant in there and want to do sub-metering.

House and ADU and garage on 200A feels like too much of a cram. Future stuff happens. You never know what's going to come.

Diversity of load counts too. You're not gonna run all 3 shop tools at the same time as you're running the car lift and garage heater.
 

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Discussion Starter · #13 ·
So my plan was put a panel in the garage for it and the ADU and the house would be a sub-panel off of it. Are you suggesting powering the garage and ADU off one of the disconnect panels?

thanks for you input.
Mike
 

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Yeah, that way the garage dwelling and house aren't forced to share 200A, which seems a little tight for now and future needs.

Plus I think you are overestimating the load in the shop as I discussed. So it seems to me like having the garage share a 200A panel with the shop instead of the house makes more sense. Perhaps I am misunderstanding your loads.

Keep in mind you're only allowed one feeder per building.
 

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Discussion Starter · #15 ·
Got it. I think that’s good suggestion. So let’s say I go with a 100 amp panel in the garage which is likely plenty, how large of a panel can I put in the garage/ADU. Could I go with 150 amp? I guess both runs are tied to 200 amp panel so that’s the limiting factor either way
 

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My thread here might interest you....

SE Harper is generally right on the money, but the picture of the meter main he posted isn't 2020 compliant, if you're on the 2020 code. This is the one I'll be using and is 2020 compliant:

https://s3.amazonaws.com/dcc-data-e...ng Flyer/SIE_FL_230-71_MeterMain.pdf?10102022

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Surge protection is no longer optional, it's now required. The Siemens FS140 seems to be the best one on the market at the moment. I have 2 on back order, Got them on Amazon for $195 before they raised the price $65 :(.
 

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Discussion Starter · #18 ·
Thank You, All this helps. I did read through your thread and there is a lot to consume there. I will go over it a couple of more times. I do have a few questions now.
1. Did you get this installed yet? If you did how did it go?
2. I like the meter socket you used, but I was wondering if you see any issue with the one I'm proposing? I don;t have an issue changing, availability might dive the choose in the end.
3. Do I have an issue with the second panel in the attached garage/ADU? (1 feeder issue)
4. I still don't feel confident in my wire sizing. Any comments or suggestions would be greatly appreciated.

BTW it looks like the FS140 is back to the $200 range.
MIke
 

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If you're not comfortable with 4/0 wire - and honestly I have concerns if you read 310.15(B)(7) closely - then use 250 kcmil Al - that's a no-brainer as it is natively 205A wire, and we're not relying on residential derates at all.
 

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If you're not comfortable with 4/0 wire - and honestly I have concerns if you read 310.15(B)(7) closely - then use 250 kcmil Al - that's a no-brainer as it is natively 205A wire, and we're not relying on residential derates at all.
At the local SH here, 4/0-4/0-4/0-2/0 is $6/ft
250-250-250-3/0 is $7.50/ft.

Really not a huge price difference, or a large chunk of the overall costs involved.
 
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