Breaker Panel Load Limits

[mrfixit247]

How do you deterimine how many breakers at certain amps is the max load limit for a panel? Thanks in advance.

[Wgoodrich]

If a dwelling main service panel then you would perform a dwelling demand load calculation. Remember that not all breaker loads will be used at the same time. This is called intermittent load. Much the same applies if it is a commercial or industrial service.

Tell us what type of service you have then we can guide you trhough the proper demand load calculation to tell you the minimum service size requried per the NEC then you can make an informed decision as to whether you need or want to upgrade you service or add load to it.

Commercial demand load is calculated much different that residential demand load. We need what type of building this service supplies power to, then we can help guide you.

Even though you may have a 1000 amps worth of breakers in a panel does not mean your panel is overloaded. The NEC sets guidelines as to adjusting for hte intermittent loads.

Hope this helps

Wg

[mrfixit247]

The Service Panel Is For A Hotel The Main Breaker Is 225.
Want It to Service More HVAC Wall Units Heat 15.7/14.2 Cooling 5.8/6.3 amps About 15 Units Plus What Ever Else In The Loadcenter Already

[imported_Ron]

mrfixit247,
You call it a load center, does it have only a handfull of breaker positions? Could it even handle the 30 pole positions required for the 15 units (assuming 208V single phase)?
Could we apply 220.30(C) or the table 220.32.
I would guess the demand factor permitted by the table 220.32, of 40%, could be applied assuming each of the 15 units where in different dwellings. That total plus the existing load might exceed the 225A feeder/panelboard rating.

[Wgoodrich]

Ron, you are partially correct about part of this building being intermittent load allowed to be calculated at 100% however a hotel does not meet the definition of a dwelling whether multifamily or single family.

We would be allowed to calculate the general lighting in 220.3.A at 100% without the continuous load adjustment of the 25% of continuous yet anything outside those sleeping rooms will have to be considered as continuous in calculations same as any other commercial building.

What we need now is total square feet of sleeping area multiplied by number of sleeping areas.

Then we need any appliances or cooking set up in each sleeping room.

Then we need a list of each non sleeping room, size and loads in each room more than 600 watts and fastened in place.

Then we need accurate existing heat or cooling and any other appliance or motor loads in that building plus the future added loads he has told us about.

We need also to know if this building is served single phase or three phase service.

Then we can calculate the commercial demand load using 220.3.A then 230.42.A then 220.21 then 220.3.B then 220.13 then 220.14 then 220.20 to calculate if this is only single phase. If it is three phase then we will have to balance the load onto three phases.

Ron, the Code you were searching for to allow diversification is found in noncoincidental load adjustment allowed found in 220.21.

Hope this helps

Wg

[mrfixit247]

Thanks For Your Help and Knowledge