demand load of exsisting panel.

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tschepers

Member
Location
South Florida
installed a new 400a service, due to an existing 100a sub panel fed by a 100a auto transfer switch, the inspector wants a panel schedule with demand loads for this panel, how do i do come up with the demand loads:-?
 

bob

Senior Member
Location
Alabama
installed a new 400a service, due to an existing 100a sub panel fed by a 100a auto transfer switch, the inspector wants a panel schedule with demand loads for this panel, how do i do come up with the demand loads:-?
Is this residential or commercial load?
 

mcclary's electrical

Senior Member
Location
VA
installed a new 400a service, due to an existing 100a sub panel fed by a 100a auto transfer switch, the inspector wants a panel schedule with demand loads for this panel, how do i do come up with the demand loads:-?


The WH is continuous demand unless it's over 125 gallon
The heat is continous demand
The rest are normal calc. loads


unless this is commercial, then there could be more(ofcouse I could have forgot some
 

Hameedulla-Ekhlas

Senior Member
Location
AFG
installed a new 400a service, due to an existing 100a sub panel fed by a 100a auto transfer switch, the inspector wants a panel schedule with demand loads for this panel, how do i do come up with the demand loads:-?
Use NEC-2008 and find out the new demand load and check the existing load.
Every electrical system designs after applying demand factor and find out the existing load plus the new demand load. If you can not calculate ask help from an electrical engineer to do the calculation properly.
 

chris kennedy

Senior Member
Location
Miami Fla.
Occupation
60 yr old tool twisting electrician
installed a new 400a service, due to an existing 100a sub panel fed by a 100a auto transfer switch, the inspector wants a panel schedule with demand loads for this panel, how do i do come up with the demand loads:-?
Whats on the 100A sub? What jurisdiction are you working in?
 

realolman

Senior Member
That's interesting.

due to an existing 100a sub panel fed by a 100a auto transfer switch, the inspector wants a panel schedule with demand loads for this panel, how do i do come up with the demand loads
because there is a 100 a sub panel that is fed by a 100 a automatic transfer switch, he wants a panel schedule with demand loads. So his concern is what?... that the sub panel's load is more than 80 amps continuous? Or that the feeding panel is overloaded? Or that the generator is too small?. You need to know what he's concerned about .


You're going to have to identify the loads. Any load that will be there for more than 3 hours is continuous. Any loads that will likely not appear together do not need to be added together... for example, you wouldn't think you'd have air conditioning and heating on at the same time. Any loads that CAN'T be turned on at the same time because of the way they are wired, don't need to both be added... just the largest.

Once you find out what he's concerned about, I think you ought to be able to satisfy the inspector yourself, without an engineer..
 

petersonra

Senior Member
Location
Northern illinois
Occupation
engineer
installed a new 400a service, due to an existing 100a sub panel fed by a 100a auto transfer switch, the inspector wants a panel schedule with demand loads for this panel, how do i do come up with the demand loads:-?
How does he get off demanding anything for something existing?

OTOH, you are going to have to do a load calculation for the new service anyway, and that would mean you have to include what's on that subpanel, so it should not be a big deal to give him what he wants.
 

Smart $

Esteemed Member
Location
Ohio
How does he get off demanding anything for something existing?

...
Actually, to confirm Code compliance he must request a load calculation or its NEC approved alternate, if previously not submitted. There is no guarantee it is as it was installed (and Code-compliant when installed), and to prove such would essentially require the calc' or its alternate anyway.
 

chris kennedy

Senior Member
Location
Miami Fla.
Occupation
60 yr old tool twisting electrician
What jurisdiction are you working in?
That's interesting.



because there is a 100 a sub panel that is fed by a 100 a automatic transfer switch, he wants a panel schedule with demand loads. So his concern is what?...
The concern is that the genny can handle the whole load if someone is not home to do manual load shedding. This is as per Broward County Board of Rules & Appeals Policy # 06-01 issued by Tarry Baker effective 11/01/06. Thats why I asked in which jurisdiction.
 

Cavie

Senior Member
Location
SW Florida
installed a new 400a service, due to an existing 100a sub panel fed by a 100a auto transfer switch, the inspector wants a panel schedule with demand loads for this panel, how do i do come up with the demand loads:-?
The demand load the inspector wants is the connected load that will be utilized by the 100 amp panel when fed by the generator. Add up all the loads that are connected to the 100 amp panel. Don't count the breaker sizes, count the connected load that is likely to be used. The idea is to not overload the generator with the auto transfer.
 

inspector141

Senior Member
Location
Westminster, MD
You need to follow the rules spelled out in 220.87 (2008 NEC)
220.87 is permissable, but only with a recordable meter over a long duration during its peak times. Alot of work for a simple calculation. But, section III of article 220 might put calculation over 100 amps and if that is the case, then this might be a compliant alternative to get the calc below 100 amps.

220.80, which someone mentioned in an earlier post, is not permissable because the sub panel does not serve the entire load of the dwelling unit.

This leaves article 220, section III if recordable ammeter is not viable.

Marty
 
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