Residential Service: Need more than 200 amps

Status
Not open for further replies.

aftershock

Senior Member
Location
Memphis, TN
I couldn't think of a good title, but, here it goes.
I will be wiring a home for a contractor friend of mine.This home will be mainly all electric so I know 1 200 amp panel will not suffice.
First of all, the city will besupplying a 400 amp service. The service equipment will be located away from the house, approx 50 ft. From there the wires feeding any panels within the house will have a 3 inch schedule 80 PVC available as a raceway.
The PVC will come up on an inside wall in the garage. I need to find/figure out a code compliant configuration to accomodate the panels I need. He also wants a back up generator.
Question 1. Is there such thing as a 300 amp panel?
Question 2. Could I actually run the panel feeds for 2 200 amp panels in a 3 inch pipe? Once I get at the panels, How would I seperate and accomodate for a back up generator?
Question 3. Will my ground rod need to be at the service equipment, or at the house, or both?
Question 4. Should I Install a trough at the service equipment with main disconnects for my panels, then bring both feeds through the 3 inch pipe?
Qestion 5. Am I asking too many questions? :oops:
 

dnem

Senior Member
Location
Ohio
Re: Residential Service: Need more than 200 amps

aftershock said:
I couldn't think of a good title, but, here it goes.
I will be wiring a home for a contractor friend of mine.This home will be mainly all electric so I know 1 200 amp panel will not suffice.
First of all, the city will besupplying a 400 amp service. The service equipment will be located away from the house, approx 50 ft. From there the wires feeding any panels within the house will have a 3 inch schedule 80 PVC available as a raceway.
The PVC will come up on an inside wall in the garage. I need to find/figure out a code compliant configuration to accomodate the panels I need. He also wants a back up generator.
Question 1. Is there such thing as a 300 amp panel?
Question 2. Could I actually run the panel feeds for 2 200 amp panels in a 3 inch pipe? Once I get at the panels, How would I seperate and accomodate for a back up generator?
Question 3. Will my ground rod need to be at the service equipment, or at the house, or both?
Question 4. Should I Install a trough at the service equipment with main disconnects for my panels, then bring both feeds through the 3 inch pipe?
Qestion 5. Am I asking too many questions? :oops:

Question 1 A panel with a 300 amp main available isn't hard to find. The thing you need to know is, if a 300 amp panel is available that is affordable for home use or if you're better off with separate smaller panels. I'll let somebody else answer that one. Pricing is a weak point for me.

Question 2 How are you going to deal with the single feed restriction of 225.30 ? Is there an overcurrent device at the meter location that you said was "service equipment" 50 feet away from the house ?

Question 3 House, definitely yes. Possibly at both house and remote service. Once again: Is there an overcurrent device in the "service equipment" 50 feet away from the house ?
If it's just a meter, then you don't need the ground rod unless required by the utility or local code. If it's a meter / OC combo, it needs "All grounding electrodes ... present at each ... structure served shall be bonded ... Where none ... exist ... one or more ... shall be installed" 250.50

Question 4 I want to get more info about how your situation is affected by 225.30 before I add my 2 cents on this one

Question 5 Definitely not ! Ask before you put it in, don't do it once and then get the bad news from the inspector that you have to redo it.

David
 

tshea

Senior Member
Location
Wisconsin
First thing to do is check with the AHJ and find outif there are any local codes, etc.

As for a configuration: 2-200Amp panels are probably more economically than 1 300A panel plus you will have many more spaces in the 200A panels.

One way this could be done is to install a wiring trough where the 3" PVC enters then put both 200A main breaker panels above the trough. Do all the bonding and grounding as required.

You could then run your service wires to the trough in the 3".

Couple questions? Is the meter 50' away from the house? Is this considered the main for the service by local AHJ? Is the PVC and service wires your responsibility or the POCO?
 

stew

Senior Member
325 meter bas 2 2inch pipes thru the wall to 2 200 amp service panels is the way we would do this. very simple and economical. There are lugs in the 325 meter base for this and the base is wide enough that it has 2 kos for the pipes. you can also come out the side of the base and lb into the structure if you want. lots of differnet ways to pipe it but this is in my opinion the easisest and most inexpensive way to get what you need. Now all that being said how do you know without a load calc whether you REALLY need more than 200?
 

stud696981

Senior Member
In regards to the 300 Amp panel.................Lighting and Appliance panels can only be 225 amp max. They are defined as 10% or more of the circuits have a neutral connection. You panel will most likely fit the definition of a lighting and appliance panel.
 

suemarkp

Senior Member
Location
Kent, WA
Occupation
Retired Engineer
For question 2, you need to find out if there are things he will not be able to run from the planned generator, or if there are items he doesn't mind not being able to run. How big will the generator be and what size panel should it feed?

Manual transfer switches (without overcurrent devices) are available in 100A and 200A sizes for a reasonable cost. Putting in a 400A main panel and a 400A transfer switch would costs thousands. Putting in two 200A panels and a 200A transfer switch could be done for about $600 in materials.

If you only need a 300A service and all the generator loads could fit in a 100A panel, then you could put in a 200A panel, and a 100A transfer switch feeding a 100A panel.

A manual transfer switch with no integral overcurrent protection must be adjacent to its main breaker. You'll have two main breakers in this install -- one on each of the two panels (200A/200A or 200A/100A).

If the homeowner can give no guidance, I'd put in a 200A transfer switch on a 200A panel and put the impossible things to power from a generator in the non transfer switch panel (like a heat pump, probably the electric range, probably the clothes dryer, maybe the water heater). Make sure the critical things are in the transfer switch panel (refrigerators/freezers, sump/water pumps, microwave, most 120V receptacles, lighting circuits, security systems, VDV panel, etc).

I'd also install a trough under the panels and transfer switch. This will give you a single place to run your ground electrodes from, as you'll have a full size neutral here to tap from. One #6 to ground rods (or maybe a #2 to a concrete encased electrode), a #2 or #1/0 to the water pipes. You can also run power taps to the panels from here. This allows three full size conductors from the meter, and those can be sized per 310.15(b)(6) if this is a dwelling. I'm not sure if you can use that table if you try to run smaller parallel sets of wire from the meter to the house, because you'll have more than 3 current carrying conductors which gets you into derating territory.
 

petersonra

Senior Member
Location
Northern illinois
Occupation
engineer
stud696981 said:
In regards to the 300 Amp panel.................Lighting and Appliance panels can only be 225 amp max. They are defined as 10% or more of the circuits have a neutral connection.

Where does the code say either of these things?
 

infinity

Moderator
Staff member
Location
New Jersey
Occupation
Journeyman Electrician
stew said:
325 meter bas 2 2inch pipes thru the wall to 2 200 amp service panels is the way we would do this. very simple and economical. There are lugs in the 325 meter base for this and the base is wide enough that it has 2 kos for the pipes. you can also come out the side of the base and lb into the structure if you want. lots of differnet ways to pipe it but this is in my opinion the easisest and most inexpensive way to get what you need. Now all that being said how do you know without a load calc whether you REALLY need more than 200?


If the service equipment is 50' away from the house, as outlined in the OP, than the conductors between the service equipment and the house would be feeders. A building or structure is required to be fed from only one set of feeders. IMO running 2-2" feeders would violate 225.30
 

aftershock

Senior Member
Location
Memphis, TN
Right now, the permanent service equipment has not been build yet. We will be working off of a temporary service with 1 GFI rec.

Anyway,, I got off the phone with the contractor. I am going to have his stub out 2-2" sch 80. I have been racking my brains on trying to figure out the best configuration. He is pouring the footing for this house tomorrow.

The meter will be built and wired from the transformer at about 50' away from the house. I am thinking I will go with a weatherproof trough, 2 200 amp weatherproof diconnects. I guess I will LB out of the backsides of the disconnects and connect from there.

My next step will be figuring out the backup generator. I guess I could go with him placing the generator near the service equipment and place the transfer switch on the load side of one of the diconnects, or place the transfer switch inside the garage between the 2 panels and choose one panel for it to serve.

I am so used to everything being on the house, service and all,, this one is a first for me,, having the service equipment away from the house like this. Also,, this contractor wants to have less (if not no) type of electrical equipment exposed on the outside of the house. Except ofcourse the A/C disconnects and such.
 

Jim W in Tampa

Senior Member
Location
Tampa Florida
I think your adding work and cost.See no reason for disconnect and then a panel.2 panels with main breaker fed from trough inside would be lot easier and cheaper.You could run 2 sets of wires but why not just run i set in 3 inch
 

aftershock

Senior Member
Location
Memphis, TN
Jim W in Tampa said:
I think your adding work and cost.See no reason for disconnect and then a panel.2 panels with main breaker fed from trough inside would be lot easier and cheaper.You could run 2 sets of wires but why not just run i set in 3 inch

Contractor could only find 2.5 inch sch 80 and he is pouring the footing tomorrow. On a quick decision, I instructed him to go ahead and stub 2-2" sch 80, at 32" apart.

I did not think 2.5" would be large enough for the wire to cover 2-200 amp panels.
 

stud696981

Senior Member
stud696981 wrote:
In regards to the 300 Amp panel.................Lighting and Appliance panels can only be 225 amp max. They are defined as 10% or more of the circuits have a neutral connection.


Where does the code say either of these things?
_________________
Bob
------------------------------------------------------------------------------
The part about 10% appears to have changed, the current code doesn't say neutral connections, just 10% supplying lighting and branch circuits.(408.14)

As far as the 225 amp max goes, I can't locate it, either this was something I read in one of my old text books and was deleted from the NEC over time or I got it confused with something else.
 

mikeames

Senior Member
Location
Germantown MD
Occupation
Teacher - Master Electrician - 2017 NEC
I personally would do one laterial from the disconnect in 3" then go to a 300 amp panel that has a feed through bus. Come out the bottom or side and hit a 200 amp main lug panel. The OCP for that panel would be in the 300 amp panel. The buss isnt actually feed through its has a 200 amp tap off a breaker. Its a panel thats specifically designed for these type of residential services.

As for the generator well it could be expensive because of the 400 amp XFR switch, but that burns me up sometimes. People want the big house and the generator but dont want to pay the extra money to have it dones right. They want all the bells and whistles for the same price of a standard 200 amps service with a small xfer switch. With a big hous I would want the whole house feed from the generator so i as the home owner could determine what loads to shead or turn on. Having the critical circuits in one panel gets the job done but limits it.

I, personally maybe because we are in the trade like the flexability of having the power where i want it when I want it. I put my house on a main XFER switch and I have done them the other way for people.
 

dnem

Senior Member
Location
Ohio
Jim W in Tampa said:
I think your adding work and cost.See no reason for disconnect and then a panel.2 panels with main breaker fed from trough inside would be lot easier and cheaper.You could run 2 sets of wires but why not just run i set in 3 inch

"You could run 2 sets of wires ....."
What about 225.30 or if there's no main at the remote meter location 230.2 ?
The two sets of wires would be supplying the two panels independently. Even tho they're in the same conduit, they can't be considered parallel conductors unless they terminate at the same terminations on both ends.

David
 

dnem

Senior Member
Location
Ohio
stud696981 said:
stud696981 wrote:
In regards to the 300 Amp panel.................Lighting and Appliance panels can only be 225 amp max. They are defined as 10% or more of the circuits have a neutral connection.


Where does the code say either of these things?
_________________
Bob
------------------------------------------------------------------------------
The part about 10% appears to have changed, the current code doesn't say neutral connections, just 10% supplying lighting and branch circuits.(408.14)

As far as the 225 amp max goes, I can't locate it, either this was something I read in one of my old text books and was deleted from the NEC over time or I got it confused with something else.

So in a residential building, your main panel would be classified as a lighting and appliance branch-cicuit panelboard 408.34(A).
If there was a GeoThermal heating panel it would be classified as a power panelboard 408.34(B).

My question is this:
Other than the max 42 OC restriction on the lighting panel 408.35, What are the real life everyday situations in which the two panels are treated differently ?

David
 

aftershock

Senior Member
Location
Memphis, TN
:shock:
The inspector came out and failed my temporary meter/panel/GFI rec assy. today.
I ran a ground as well as a neutral from the meter socket to the panel. He wants the ground removed. I placed a 1/2" connector at the bottom of the meter center for the bare ground to go through for the ground rod. He wants the connector removed. They run their grounds bare, and I mean without any condiut for the ground rod. :shock:
I scratch my head on this,, but oh well,, I will make corrections as he wants.

More updates as I go along.
 

Jim W in Tampa

Senior Member
Location
Tampa Florida
aftershock said:
:shock:
The inspector came out and failed my temporary meter/panel/GFI rec assy. today.
I ran a ground as well as a neutral from the meter socket to the panel. He wants the ground removed. I placed a 1/2" connector at the bottom of the meter center for the bare ground to go through for the ground rod. He wants the connector removed. They run their grounds bare, and I mean without any condiut for the ground rod. :shock:
I scratch my head on this,, but oh well,, I will make corrections as he wants.

More updates as I go along.

He had you remove the ground because it would be a parallel neutral.You only run 1 neutral to panel and bond at panel,after that you seperate neutral and grounds.The other part makes no since
 
Status
Not open for further replies.
Top