How does the NEC 220 Home Load Sizer & A/C Surge Calculator work?

Simulates whole-home circuit loads, simultaneous utility demand, and compressor inrush amps to prevent generator breaker trips during outages.

Are the electrical and fuel calculations grounded in official building codes?

Yes. All mathematical models follow National Electrical Code (NEC Article 220, 250, 702) and National Fuel Gas Code (NFPA 54) engineering guidelines.

ReaLoadREVIEWS

Home Backup & Portable Power Guide

Interactive Sizing & Planning Suite

Power Calculators & Home Hookup Sizers

Synced with: GENMAX GM10500XiT

1. Natural Gas Hose Size & Pressure Drop Calculator

Undersized 1/2" hoses restrict gas flow on 25ft runs and starve 450cc+ engines under load. Keep pressure drop below 0.50" Water Column (WC).

Generator Running Watts (NG)Hose Length from Gas Meter (ft)Hose Inner Diameter (ID)90° Brass Elbows / Tees (+5ft eq.)

Pipe Bore & Pressure Drop Comparison (91,800 BTU/hr · 92 CFH)

Interactive Sizing Suite

Power Calculators & Tools

Pre-populated for GENMAX GM10500XiT

Interactive Sizing & Planning Suite

Power Calculators & Home Hookup Sizers

Synced with: GENMAX GM10500XiT

120V / 240V Split-Phase Appliance & Circuit Load Simulator

Interactive Load Test: What Can This Generator Power?

Test Fuel Output:

Continuous Running WattsSafe Load (<85%)

4,600 W / 8,000 W (57%)

Motor Starting Surge(Highest Motor Surge: +2,100 W from 3.5-Ton Central A/C (240V))

6,700 W / 10,500 W (64%)

Pass: GM10500XiT comfortably powers all 6 active appliances on gasoline.

HVAC

3.5-Ton Central A/C (240V)

Running: 2,800 WStarting Surge: 4,900 W (-65%)

HVAC

ECM Gas Furnace Blower (1/2 HP)

Running: 420 WStarting Surge: 850 W

Water & Utility

Submersible Deep Well Pump (1/2 HP 240V)

Running: 780 WStarting Surge: 1,950 W

Kitchen

Energy Star Kitchen Refrigerator

Running: 220 WStarting Surge: 680 W

Kitchen

Garage Chest Deep Freezer

Running: 160 WStarting Surge: 520 W

Water & Utility

Whole-House LED Lights + Starlink + APC UPS

Running: 220 WStarting Surge: 280 W

RV & Tech

Dual 15,000 BTU Rooftop RV A/Cs

Running: 2,900 WStarting Surge: 4,265 W (-65%)

RV & Tech

RV Convection Microwave + Fridge + Converter

Running: 2,150 WStarting Surge: 2,600 W

Jobsite

1.5 HP Air Compressor + 15A Miter & Table Saw

Running: 3,800 WStarting Surge: 7,400 W

Jobsite

Commercial Battery Bank + LED Work Towers

Running: 1,450 WStarting Surge: 1,600 W

Water & Utility

240V Electric Water Heater (4,500W Element)

Running: 4,500 WStarting Surge: 4,500 W

Water & Utility

Basement Sump Pump (1/2 HP 120V)

Running: 800 WStarting Surge: 2,100 W