How many sub panels?

[Junkman]

I have a 200 amp service in the cellar of the home. How many sub panels can I run off of this main panel? I am thinking 60 amp to a upstairs, 100 amp on the side of the main since the main is already full, and a 100 amp out to the garage. Last question... can you run a sub panels off of another sub panel? The reason for this is because when I upgraded the original service by adding a generator disconnect, the inspector said that the original main panel now becomes a sub panel, and that I needed to separate the grounds from the neutrals. I did this at the time. thanks

 

[-JP]

You can have as many "sub panels" as you want to install as long as they are connected correctly.

The key issue to focus on is the utility service must be sized to handle the anticipated load. The service size and limiting factor is the overcurrent device ampacity on the service entrance equipment which in your case appears to be 200 ampere.

You can have a million "sub panels" with a hundred-million ampere connected load all fed from your 200 ampere rated service as long as the total demand of all the panelboards combined does not exceed 160 amperes.

 

[kbs2244]

This brings up something I have been thinking about.
I like to use a lot of low draw circuits.
To get more CB slots can I put a second “main” box next to the existing one and jumper the meter feeds over to it?
I am trying to avoid the work and expanse of install a new “main” box just for more slots.

 

[-JP]

kbs2244:

NO. You can not jump off the existing service disconnect and extend the service entrance conductors to an additional panelboard. This would create an unsafe condition as well as multiple code violations.

JP

 

[Nostraquedeo]

This brings up something I have been thinking about.
I like to use a lot of low draw circuits.
To get more CB slots can I put a second “main” box next to the existing one and jumper the meter feeds over to it?
I am trying to avoid the work and expanse of install a new “main” box just for more slots.

Typically, in this case you would have feed lugs on the opposite site of the main breaker or in-coming lugs. You would basically be creating a second panel section. In your case look at the 10 foot tap rule.....

Secondary conductors can be run up to 10 ft without overcurrent protection, but they must be installed in accordance with the following requirements:
(1) The ampacity of the tap conductor is:
Not less than the computed load in accordance with Article 220, and
Not less than the rating of the device supplied by the tap conductors or the overcurrent protective device at the termination of the tap conductors.
(2) The secondary conductors do not extend beyond the switchboard, panelboard, disconnecting means, or control devices they supply.
(3) The secondary conductors are enclosed in a raceway.

This is appies to a tap, not intercepting the service feeds.

 

[Aceman]

fed from your 200 ampere rated service as long as the total demand of all the panelboards combined does not exceed 160 amperes.

Which code article prevents me from loading my service up to the full 200 amps? There is very little in a home that is considered a continuous load...

 

[Nostraquedeo]

Most likely your main breaker is not going to be rated for 200 amps of continuos load. You might see a fully rated breaker in commercial use, but not very common in residential.

 

[mrb]

Most likely your main breaker is not going to be rated for 200 amps of continuos load. You might see a fully rated breaker in commercial use, but not very common in residential.

cant load a breaker to more than 80% of its rating with continuous load, residential or commercial.

 

[Number21]

There is very little in a home that is considered a continuous load...

Anything that is hard wired and not plugged in is a "continuous load" as far as the NEC is concerned. Lights, appliances, etc...

 

[ddawg16]

Following this idea.....

My garage sub panel is feed from a 50A breaker in my main 200A panel.

I have 4 20A and 2 15A breakers in the sub...total 'potential' energy usage of 110A....if I turned on all my tools at once......but that will never happen....I doubt I ever pull more than 30A at any given moment....

Same for a main panel....assuming you have a 200A main breaker....to total of the breakers in the panel (potential load) can be more than the 200A (and in most houses is already that way)....but in most houses, you don't get close to the 200A (160 continous).

 

[Aceman]

Anything that is hard wired and not plugged in is a "continuous load" as far as the NEC is concerned. Lights, appliances, etc...

Then give me a code article. Because the code article I'm reading from, Art. 100 definitions lists "continuous load" as being a load where the maximum current is expected to continue for 3 hours or more.

How many appliances do that?

Again, which code article is keeping me from using that 200 amp breaker at full ampacity?

 

[kbs2244]

Nostraquedeo:

So if I put the second panel right next to the first and if I come off the load side of the mains on the first panel and go to the line side of the mains on the second panel I am legal?

 

[larry4406]

Right or wrong, all inspected, I have two 200 A panels in my house for 400A service. One has a 100A breaker feeding a sub panel on the other end of the house. That feeds a 100A panel in my detached garage. The garage panel then feeds a 60A sub panel in the garage loft.

The neutral and the ground are not bonded via removal of the ground screw in all panels down stream from the house panel.