Demand Loads for Single Family Dwelling per NFPA 70A

[bearthebuilder3000]

Hi Everyone,

I'm an architect / builder working on a new spec house prototype and I was hoping to get some guidance on how to determine the overall demand load for the electrical panel. I'm pretty well versed in FBC and navigating code in general, but I'm new to electrical design and NFPA 70A has been a bit challenging.

I've put together my panel schedule and figured out all of my connected loads , but I cant seem to figure out which demand factors to apply to which connected loads in order to determine the total demand load for the panel. I've linked a working copy of the plans and schedules. Any insight would be appreciated.

Linked Plan & Schedules - Please disregarding circuit callouts on plans. That was a first pass and has not been updated to match the linked panel schedule

Connected Loads

• Lighting: 1.25 KVA
• Receptacles: 9.42 KVA
  • Only includes 110V receptacles
• Motors: 0.90 KVA
  • (2) 50W exhaust fans (Not sure if this is miscategorized. I've sometimes seen it listed under lighting)
  • (1) 800W Garage Door Opener.
• AC: 1.3 KVA
  • AHU only
• Heating: 5.0 KVA
  • Supplemental heat kit only. Condensing unit omitted as non-coincidental.
• Kitchen: 16.05 KVA
  • Includes small appliance circuits plus all kitchen appliances.
    • Should kitchen appliances be included here or should they be included under receptacles?
• Other: 12.25 KVA
  • Includes water heater, dryer, washer, and smoke detectors
• Total Connected Load = 46,170 VA / 240V = 192.38 A
  • This is where I'm stuck. I've been reviewing NFPA 70A for the last two days but don't understand how to get from the total connected load to the demand load.

 

[Elect117]

To start, it is called NFPA 70 or the NEC. Calling it 70A is a little funny.

You would be referencing article 220 and can use either the standard method or optional method. The standard method starts at 220.40 and the optional method starts at 220.80.

When using the standard method, you move through each permissible reduction and apply it. For example, the lighting, your small appliance branch circuit and laundry circuit loads are allowed to be reduced based on table 220.42.

The optional method is much easier to calculate and typically results in a lower required value.

If you have a copy of the NEC or have NFPA link then you can use the examples in the annex to help.