Max Load On Residential Panels

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S7VEN

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Hey everybody, have a general question about actual Loads on panels which might be stupid for some..

ex: what is the maximum amp load you can have on a 100 amp panel?

can you max out a residential panel carrying an actual 100 amp load for long periods of time?
or because it is also on a ocpd from the utility company you can only carry 80 amps max (80%) for long periods of time?

being that you can size a panel for over 100 amps, since everything won't be in use at the same time, can it's realistic full load be 100 amps? as in 100 amp reading with a meter

thanks
 
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JoeStillman said:
All of the residential calculation methods in 220 give non-continuous loads (I confirmed this with NFPA).
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Calculations include continuous & non continuous load for the FLA -- Are you implying that a residential load calc per Art 220 can only be 80% of the service OCPD?
 
JoeStillman said:
All of the residential calculation methods in 220 give non-continuous loads (I confirmed this with NFPA).
Click to expand...
Properly stated, the calculations of Article 220 do not factor continuous loads by 125% as required for the determination of minimum OCPD ratings and minimumn conductor sizes.
 
S7VEN said:
Hey everybody, have a general question about actual Loads on panels which might be stupid for some..

ex: what is the maximum amp load you can have on a 100 amp panel?

can you max out a residential panel carrying an actual 100 amp load for long periods of time?
or because it is also on a ocpd from the utility company you can only carry 80 amps max (80%) for long periods of time?

being that you can size a panel for over 100 amps, since everything won't be in use at the same time, can it's realistic full load be 100 amps? as in 100 amp reading with a meter

thanks
Click to expand...

There is no POCO ocpd to speak of. A high voltage transformer fuse won't be any help for overloads at 120/240 volts. We fed "regular" residential 200 amp overhead services with triplex as small as #4 and as large as 4/0. Aluminum, not copper. Length of service was a factor but there was an element of randomness too, no doubt. Burning up a residential service due to overload was an *extremely* rare event for us.

Iron_Ben
 
Most panelboards used in dwellings will eventually fail if loaded to even 80% continuously, especially if it has a plug on main breaker opposed to a bolt on main, just an observation I have had over several years.

Those 100 amp panelboards that hold the main when the questionable load is first added eventually have something fail 5 maybe 10 years later.
 
Smart $ said:
Where'd you get that from???
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(7) 1201240-Volt, Single-Phase Dwelling Services and
Feeders.
For one-family dwellings and the individual
dwe11ing units of two-family and multifamily dwellings,
service and feeder conductors supplied by a single-phase,
120/240-volt system shall be permitted be sized in accordance
with 31 0.15(B)(7)(l) through (4).
(l)
For a service rated 100 through 400 A, the service
conductors supplying the entire load associated with a



one-family dwelling. or the service conductors supplying

the entire load associated with an individual dwelling

unit in a two-family or multifamily dwelling, shall

be permitted to have an ampacity not less than 83 percent

of the service rating.

(2) For a feeder rated 100 through 400 A, the feeder conductors

supplying the entire load associated with a onefamily

dwelling, or the feeder conductors supplying the

entire load associated with an individual dwelling, unit

in a two-family or multifamily dwelling, shall be permitted

to have an ampacity not less than 83 percent of

the feeder rating.

(3) In no case shall a feeder for an individual dwelling unit

be required to have an ampacity greater than that specified

in 310.15(8)(7)(1) or
(2).



(4) Grounded conductors shall be permitted to be sized

smaller than the ungrounded conductors, provided that

the requirements of 220.61 and 230.42 for service conductors

or the requirements of 215.2 and 220.61 for

feeder conductors are met.

 
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