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Machine Shop Power Budget Calculator - Local Load Rows & Source Warnings

Total up your shop equipment loads, check for phase imbalance, and size your electrical service

Free machine shop power planning screen for early electrical conversations in workshops, fabrication shops, and garages with heavy equipment. Build a local equipment inventory for lathes, mills, welders, plasma tables, air compressors, dust collectors, lighting, and heaters, then compare connected kVA, local diversity assumptions, local shop-duty assumptions, continuous-load planning adders, and service comparison tiers. Outputs are source-gap screens only: actual service sizing, conductor and OCPD selection, largest-motor treatment, phase balance, phase-converter suitability, voltage drop, fault current, utility service, permits, inspections, and energization decisions require the adopted NEC, equipment nameplates/manuals, utility data, product listings, and qualified electrical/AHJ review.

Pro Tip: Use the screen to build a complete nameplate checklist before you call the electrician or utility. Replace every preset HP, amp, duty-cycle, and kW row with actual equipment data, then verify the simultaneous-use basis, largest motor, starting current, VFD or phase-converter behavior, future expansion, and inspection requirements.

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Machine Shop Power Budget Calculator
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How It Works

  1. Build Your Equipment Inventory

    Add each piece of shop equipment, then replace preset rows with nameplate voltage, full-load amps, horsepower, phase, MCA/MOCP, duty-cycle, and manual data where available.

  2. Set Local Usage Assumptions

    Classify rough shop duty and continuous loads as planning assumptions only. Adopted-code demand factors, simultaneous-use basis, and largest-motor handling still require qualified review.

  3. Flag Three-Phase Questions

    Use the warning rows to identify three-phase machines on single-phase service, but verify converter/VFD derating, power quality, grounding, and manufacturer limits separately.

  4. Compare Service Tiers

    Review connected kVA, local diversity screen, local duty screen, and comparison-tier utilization before a formal NEC load calculation, utility request, or service upgrade discussion.

  5. Carry Source Gaps Forward

    Use the export as a checklist for the electrician, engineer, utility, manufacturer, and AHJ. It is not a panel schedule, circuit assignment, conductor size, OCPD selection, or permit drawing.

Built For

  • Home machinists planning electrical service for a garage conversion
  • Fabrication shop owners budgeting a panel upgrade for new equipment
  • Electricians gathering preliminary shop load assumptions before formal code calculations
  • Woodworkers calculating total demand for a shop with tablesaw, jointer, planer, and dust collector
  • Welding shops evaluating whether existing service can handle an additional welding station

Assumptions

  • Preset rows are local placeholders until replaced with actual nameplate and manual data.
  • Local diversity and duty factors are screening heuristics, not validated NEC demand factors.
  • The app does not calculate the Article 430 largest-motor feeder rule, conductor ampacity, OCPD, voltage drop, or phase balance.
  • Phase converter, VFD, CNC power-quality, utility-service, and AHJ requirements remain source gaps.

Limitations

  • Does not perform a full NEC Article 220 or Article 430 load calculation with all applicable demand factors and exceptions.
  • Motor starting inrush (locked rotor amps) is flagged but not used for detailed coordination studies.
  • Harmonic distortion from VFDs and electronic loads is not analyzed for neutral conductor sizing.
  • Utility transformer sizing and service lateral voltage drop are outside the scope of this tool.
  • Does not generate a complete panel schedule or one-line diagram for permit submission.

References

  • NFPA 70 National Electrical Code - source pointer only
  • NFPA 79 Electrical Standard for Industrial Machinery - source pointer only
  • NFPA 70E Electrical Safety in the Workplace - source pointer only
  • NEMA MG 1 motors and generators - source pointer only
  • OSHA 1910.303, 1910.147, and 1910.212 - source pointers only

Frequently Asked Questions

Start by collecting actual nameplate and manual data for every machine, welder, compressor, heater, and lighting load. This screen organizes local assumptions, but the adopted NEC method, largest motor treatment, simultaneous-use basis, conductor/OCPD selection, and AHJ interpretation control the formal result.
The answer depends on real nameplates, simultaneous use, utility service, voltage, phase, starting current, future expansion, and adopted-code review. Treat the displayed service tier as a planning comparison, not a service-upgrade recommendation.
No. The app flags source gaps and applies only local planning screens. A qualified electrician or engineer must apply NEC Article 430 and any local amendments to the actual motor group, feeder, conductor, and overcurrent-protection design.
Use this screen to identify three-phase machine questions. Final utility three-phase, converter, or VFD decisions require manufacturer limits, voltage balance, derating, grounding, power quality, listing, code, utility, and AHJ review.
The local totals can flag a review need, but simultaneous operation depends on actual circuits, conductor and breaker ratings, motor starting behavior, voltage dip, duty cycle, feeder capacity, and inspection requirements.
Disclaimer: This calculator provides preliminary source-gap load screens only. It is not an NEC load calculation of record, permit drawing, service-entrance design, conductor or OCPD selection, phase-converter approval, arc-flash study, utility approval, or AHJ acceptance. Electrical work requires qualified design, permits, inspection, and current source review.

Learn More

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Machine Shop Electrical Planning Guide

Three-phase vs single-phase power, phase converter options, panel sizing for CNC machines, VFD electrical requirements, and grounding for machine tools.

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