Tap + Breaker or an empty slot.
Use the cubic inches stamped on a plastic or nonmetallic box.
Plaster ring or extension ring. Add the volume marked on it.
Each insulated wire that comes in from outside counts as 1. A loop 12 in or longer counts as 2. Pigtails and wires that never leave the box do not count.
Up to 4 grounds count as 1 allowance of the largest ground. Each ground after that adds 1/4. 2023 NEC 314.16(B)(5).
All internal clamps together count as 1 allowance of the largest wire in the box. Connectors outside the box do not count.
Each switch or outlet counts as 2 allowances of the largest wire connected to it. Two devices on one strap still count as one.
A hickey is the threaded fitting a light fixture hangs from. Each stud or hickey counts as 1 allowance of the largest wire.
Reference only. Check the NEC and local code.
Tap a pipe to edit it.
Distance from the source to the load, not the round trip.
75°C is the usual column because of the termination rating in 110.14(C).
Default 77°F (25°C). Table 8 is published at 167°F (75°C). The result is corrected with Note 2.
Reference only. Check the NEC and local code.
Enter any two. The other two fill in. Typing a third value drops the oldest entry.
1 is unity. Use 0.8 for 80%, not 80. Three-phase multiplies by 1.732.
Reference only. Check the NEC and local code.
Top: length. Right: width. Left and bottom: from the walls. Inside: spacing.
Short summaries of NEC 2023. Check the edition your city adopted. This is not the code text.
Reference only. Check the NEC and local code.
Photos save with your account. Turn this on to put them on the panel PDF and the printout.
No photos for this panel yet. Add one from the camera or gallery.
Odd slots are the left column, even slots the right. One row is a left slot and the slot beside it, and both sides of that row are the same phase. The phase comes from the real slot number, so turning the panel upside down does not change which slot is which phase.
Most 3-phase panels do not accept tandem (twin) breakers. Check the label on the panel.
Colors are not the same on every job. Where more than one system is in the building, post the colors at the gear.
Reference only — follow NEC, panel label, and local code.
Guided sizing follows the 2023 NEC 220.82 optional calculation. General load is 3 VA per square foot, 1,500 VA per small-appliance circuit, 1,500 VA for laundry, and the nameplate of fixed appliances. The first 10,000 VA is at 100% and the rest at 40%. Air conditioning is added at 100% under 220.82(C), and an EV charger at 100% under 220.57. Motor running VA uses Table 430.248. The largest motor start is a separate surge check. It is not added on top of the running total.
Whole house counts every load in the list. Essential loads counts only the ones you check.
Central AC and heat pump presets use Generac's motor table: running amps and locked-rotor amps at 240 V, times 240. A 3-ton unit is 15 A running (3,600 W) and 75 A locked rotor (18,000 W). That 18 kW start matches Generac's public note that a 3-ton unit can need 15–18 kW to start. Half-ton sizes are the midpoint of the published ton steps.
Champion's wattage chart lists a 3-ton unit at only 3,000–3,500 W running and 5,000–6,000 W starting. That is too low for locked-rotor standby sizing. Use the outdoor unit's nameplate LRA × volts when you have it. A later Generac dealer table lists about 100 A (24 kW) for a 3-ton unit.
Kohler publishes one heat pump at 4,700 W running and 10,000 W starting, not a per-ton series. Heat pump presets here follow Generac's 1 hp per ton rule, same as central AC. Edit the watts to the nameplate.
Generac's PWRcell worksheet says a Hyper Engineering Sure Start can suppress locked-rotor amps by as much as 60%. Some kits advertise about 70%. This toggle multiplies AC and heat-pump starting watts by 0.35 (a 65% cut) and leaves every other load alone. Inverter mini-splits are not included. If the kit's sheet gives a different cut, edit the starting watts.
The same standby set is often rated lower on natural gas than on LP. Kohler air-cooled examples: 10 kW LP / 9 kW NG, 14 / 12, 20 / 18, 26 / 24. Enter both nameplate kW and this sheet compares them to the required kW. It does not invent a derate.
This is not a service-entrance calculation. Article 220 load calc is the Load Calc tool. Generator installation is NEC 702 and 445, the transfer equipment, and the manufacturer's sizing sheet.
Estimate only — confirm with manufacturer sizing tools, NEC 702/445 and local code. For service-entrance load calc use Load Calc (NEC 220).
Take or choose a photo of the breakers. A second photo of the directory, a handwritten list, or the door label is optional.
Panel photo
Directory or label (optional)
Check panel orientation
Check each row. A caution mark means that part was hard to read. Tap it for the reason, then confirm or change it. Nothing is saved until you tap Apply. Undo puts the old breakers back.