AutoCAD Load Schedule LISP: Circuits, Breakers and Phases

Traces the circuits on an electrical plan and builds a load schedule with points, load, cable, breaker and phase balance.

LOADSCHED is an AutoCAD load schedule LISP for building wiring plans. It reads the symbol legend, traces the circuits you pick on the plan, and works out the number of points, load, current, cable size and breaker for each circuit. A summary then gives the installed load, demand load, main breaker, main cable and an R/S/T phase assignment. The report is saved as a CSV file and can also be drawn into the drawing as a table.

The workflow has three commands. LOADSCHED-LEGEND asks you to window the legend table; every block is paired with its nearest description text and classified by keywords: lighting (luminaire, light, lamp, downlight, LED, emergency ...), socket (socket, outlet, receptacle), appliance (washer, dishwasher, oven, water heater, A/C, pump ...), switch, junction box, and low-voltage items (phone, TV, data, fire alarm, camera, doorbell ...). Low-voltage items are ignored, switches and junction boxes are counted but carry no load. Wattage is read from text such as '2x36W' or '18W' in the description, or from block attributes. When no wattage is given, sockets default to 300 W and appliances to a value by name, for example 2500 W for washers and dryers, 2000 W for ovens and water heaters, 1500 W for air conditioners.

In LOADSCHED-CIRCUIT you pick just one line per circuit. The tool finds every connected LINE, LWPOLYLINE and POLYLINE on the same layer with the same color, joining end-to-end and end-to-body connections; lines that only cross each other mid-span are treated as different circuits. Legend blocks around the traced lines are collected into the circuit. If a branch is missed, click it to add it to the same circuit, then right-click to move on to the next one.

Circuit current is load divided by 220 V. Lighting-only circuits get 3x1.5 mm² cable and a B10A breaker; socket, appliance and mixed circuits get 3x2.5 mm² and C16A. Cable length is taken from the traced geometry and converted to metres using INSUNITS (centimetres if INSUNITS is not set). The tool warns when a lighting circuit has more than 9 points, a socket circuit more than 7 sockets, or a circuit exceeds 2000 W. Demand load uses 60% of the first 8 kW and 40% of the rest, the three-phase demand current is P/526 (380 V, power factor 0.8), and the main breaker and main cable are picked from a lookup table.

Be aware that these rules come from the Turkish wiring regulation (Elektrik İç Tesisleri Yönetmeliği) for 220/380 V systems, not from the NEC or BS 7671. The tool takes the tedium out of filling in a schedule, but it is not a substitute for engineering judgement: check cable sizes, breakers and phase balance against your local code before issuing drawings.

How to use it

1. Load loadsched.lsp with APPLOAD; the LOADSCHED command lists the workflow and the current settings.
2. Run LOADSCHED-LEGEND and click the lower-left and upper-right corners of the legend table.
3. Review the type and wattage listed for each block, and fix the description of any entry shown as ??? before reading the legend again.
4. Run LOADSCHED-CIRCUIT and pick any line of the first circuit; all connected lines are highlighted.
5. If a branch is not highlighted, click it to add it to the same circuit.
6. Right-click to close the circuit; points, load, current, cable, breaker and any warnings appear on the command line.
7. Repeat for the remaining circuits, then right-click on an empty circuit to finish and read the summary.
8. Run LOADSCHED-EXPORT to save the CSV file, and answer Yes if you want the table drawn at a point and text height you choose.

Notes and tips

• Circuit lines must share the same layer and the same color setting; a ByLayer line and a line with an explicit color are treated as different, even if they look identical.
• Lines count as connected within a 1.5-unit tolerance, and blocks are searched within a 25-unit margin around each line. Adjust both with LOADSCHED-SET if your drawing uses a different scale.
• Because the block search uses each line's bounding box plus the margin, a symbol on a neighboring circuit that sits very close can be picked up; check the per-circuit listing.
• Phases are assigned in circuit order as R, S, T, R ... with no load-balancing optimization. Use the imbalance figure and rearrange phases in the CSV if needed.
• The English build writes a comma-separated CSV with a decimal point, which opens directly in US-locale Excel.
• Legend and circuit data live only in memory for the current session; after reopening the drawing, run the legend and circuit steps again.

Frequently asked questions