[pjbadding]

I'm preparing to build a new home that will have 400 Amp service with a main 200 Amp panel and a 200 Amp sub-panel. The home is a long ranch so the main will feed 4 bedrooms, 2 full baths, laundry room and exterior. The sub-panel will be 100' from the main and will feed the kitchen, great room, 1/2 bath and the garage/garage shop. I'm having trouble getting a straight answer on the size of the feeder cable from the main panel to the sub-panel.

What size copper feeder cable will be required between the main panel and sub-panel?

I believe I need a 4 wire feeder cable. Is this correct?

Thanks for your help!

 

[Speedy Petey]

You'll get folks to dispute this since one panel is not carrying the entire load, but here even for a 400A service with two 200A panels we would use 4/0AL (2/0CU) to feed each panel.

If using cable then yes, you need two hots, a neutral and a ground. Typical would be SER cable.

 

[pjbadding]

Is it against code to have 2 200 Amp panels for 400 Amp service?

Is it recommended to have two 200 Amp services with one feeding each 200 Amp panel? If this were done, wouldn't we need two meters with separate service cables from the utility? This just seems like it would add cost more than anything.

 

[pjbadding]

Is it against code to have 2 200 Amp panels for 400 Amp service?

Is it recommended to have two 200 Amp services with one feeding each 200 Amp panel? If this were done, wouldn't we need two meters with separate service cables from the utility? This just seems like it would add cost more than anything.

 

[Speedy Petey]

A 320/400 amp service with one meter, feeding two 200A panels, is absolutely typical and common.

 

[Speedy Petey]

Did you do a load calculation? Do you really need a 400A service?

 

[pjbadding]

I've done a load calculation and I don't need 400 but I need more than 200. My garage shop will have several 240v 30-50 Amp dedicated circuits (table saw, dust collector, welder, electric heater, etc.). I decided on going with 400 as I plan to add a separate Morton building and want to have the ability to add service to the Morton building at that time.

 

[AllanJ]

But one panel would not be a subpanel off of the other, 200 amp, panel.

Both 200 amp panels would be "main" panels, installed next to each other so the top (main) breakers of both may be flipped off at the same time.

 

[pjbadding]

One of the panels will be installed on the other side of the basement which will be 100' away from the SE so my assumption is that the panel located 100' away would be considered a sub-panel and installed as such.

 

[Jim Port]

Then you will need a disconnect next the the other panel. The disconnect will be wired as a service as well as the 200 amp main breaker panel.

 

[pjbadding]

Then you will need a disconnect next the the other panel. The disconnect will be wired as a service as well as the 200 amp main breaker panel.

My assumption is that the sub-panel would have a main breaker similar to the main panel. Does this suffice as the "disconnect" you mentioned?

 

[Jim Port]

The main in the second panel will just be a redundant switch. The services must be grouped so you will have a disconnect next to the first panel.

 

[pjbadding]

The main in the second panel will just be a redundant switch. The services must be grouped so you will have a disconnect next to the first panel.

If I may summarize...A disconnect will be placed next to the main panel. The disconnect will be fed from the main panel and the sub-panel will be fed from the disconnect. I can have a main breaker in the sub-panel if I want to be able to disconnect power to the sub-panel at the sub-panel. Is this correct? What type of "disconnect" is required in this case?

 

[joed]

The disconnect will NOT be fed from the main panel. It will be fed from the 400 amp service.

 

[pjbadding]

The disconnect will NOT be fed from the main panel. It will be fed from the 400 amp service.

OK. Then why not just feed from the 400 amp service to the 2nd 200 Amp Panel and treat them both as separate 200 amp main panels each with a main breaker?

 

[Jim Port]

The services must be grouped adjacent to each other. Since you want one panel in a different location you need a disconnect .

 

[joed]

You can't a have a 100' length of unfused conductors coming right off the 400 amp services. Plus you need to be able to turn all the power from one location with no more than 6 switches.

 

[Know A Little]

If I may summarize...A disconnect will be placed next to the main panel. The disconnect will be fed from the main panel and the sub-panel will be fed from the disconnect. I can have a main breaker in the sub-panel if I want to be able to disconnect power to the sub-panel at the sub-panel. Is this correct? What type of "disconnect" is required in this case?

You can save money in the second panel by buying a Main Lug Panel in lieu of a Main Breaker panel.

 

[pjbadding]

The services must be grouped adjacent to each other. Since you want one panel in a different location you need a disconnect .

Since I'll have more than 6 breakers in the 2nd panel, I believe I will need a main breaker at the panel in addition to the disconnect at the main panel. Is this correct?

I'm just curious, but is this 2nd panel considered a main panel since it's not coming directly off the SE panel?

What type of disconnect is required/suggested for the 2nd panel?

I really appreciate all of the great information you've provided!

 

[Speedy Petey]

Since I'll have more than 6 breakers in the 2nd panel, I believe I will need a main breaker at the panel in addition to the disconnect at the main panel. Is this correct?

As long as the main disconnect is within/on the same structure as the panel NO main or local disconnect is required.

I'm just curious, but is this 2nd panel considered a main panel since it's not coming directly off the SE panel?

It would be a main panel, but it would not be the service equipment since the main disconnect would be separate from it.

What type of disconnect is required/suggested for the 2nd panel?

Any 200A service rated fused disconnect or breaker enclosure. If it will be outdoors it would need to be outdoor rated.