Load Shed Module Programming

Why this matters

A 24 kW standby generator can serve a typical 200A residential service, but only if the home's peak load fits inside 24 kW (100A at 240V). Most homes built since 2010 with 200A service have peak loads exceeding 100A when AC, electric range, water heater, dryer, and EV charger all run simultaneously. The solution is a load-shed module (also called a "smart management module" or "load priority module") that prevents specific high-draw loads from running on generator power, ensuring the generator stays inside its capacity. Programming the module correctly is the difference between a generator that delivers backup power reliably and one that overloads and shuts down at the worst moment. The skill is brand-specific but follows the same logic across manufacturers.

When to use

Install and program a load-shed module when:

• Generator capacity is less than the home's calculated peak demand
• Customer has EV charger, hot tub, or other high-draw loads
• Customer prefers to back up entire home but does not want to upgrade generator
• The transfer switch is whole-home rather than essentials-only

Do NOT need a load-shed module when:

• Generator is sized for the full home peak (oversized installation)
• Transfer switch is essentials-only (the essential-loads panel handles selectivity)
• Customer accepts that high-draw loads will not run during outages

How load-shed works

A load-shed module monitors the generator's output (typically via current sensors on the generator output lines) and disables specific loads when total demand approaches capacity.

Two methods:

Method 1: Per-circuit disconnect (priority-based)

The module has 1 to 4 individual relays that can disconnect specific circuits. When generator load reaches a threshold, the highest-priority load (the one programmed to drop first) is disconnected. If load remains too high, the next priority drops, and so on. When load drops below the resume threshold, the loads re-energize in reverse priority order.

Typical priorities:

1. Drop first: AC condenser (highest draw, most easily delayed)
2. Drop second: Electric water heater (water stays hot for hours; can be off briefly)
3. Drop third: Electric range / oven (specific cooking events; usually delayable)
4. Drop fourth: EV charger (can wait until utility power returns)

Method 2: Capacity-based shed (overload prevention)

The module reads total generator load. If load exceeds 80 to 90 percent of generator capacity, all "managed" loads drop. As load decreases below the resume threshold, loads come back online in priority order.

Most modern systems use a hybrid: per-circuit priority within capacity-based logic.

Brand-specific modules

Generac Smart Management Module (SMM)

• Used with Generac whole-home generators (Guardian, Protector, EcoGen series)
• Up to 4 SMMs per system (managing 4 separate loads)
• Each SMM is rated for a specific circuit ampacity (15A, 30A, 50A, 60A versions)
• Communicates with the generator controller via dedicated wiring
• Programming via the Generac controller display or PowerZone monitoring

Kohler Power Management

• Used with Kohler Residential generators
• Similar concept; integrated load shedding
• Programming via Kohler controller

Cummins QuietConnect Load Management

• Used with Cummins residential standby
• Cellular-based programming option for some models

GE Symphony III

• Multi-priority module
• Integrated with GE residential standby

Generic third-party

For non-integrated systems (mixed brand or older generator), third-party load shed modules from Siemens, Eaton, and others provide equivalent functionality. Wiring is more complex; verify compatibility.

Procedure: Generac SMM programming example

The Generac Smart Management Module is the most common load-shed module in residential install. The configuration:

Step 1: Determine load priorities with the customer

Walk the panel with the customer; identify candidate loads for management:

The customer-specific priorities are negotiated; what the homeowner values most stays online.

Step 2: Calculate generator capacity reservation

A 24 kW generator delivers 100A at 240V continuous. Reserve 10 to 20 percent for safety margin. Usable continuous: ~80 to 90A.

If the home's "always-on" load (lights, fridge, well pump, electronics) is 30A, then the managed-load capacity is ~50 to 60A.

If the home has a 40A AC + 25A water heater + 50A range as managed loads, total = 115A. Cannot run all simultaneously on the 24 kW generator.

Load priorities determine which can run when. With AC running (40A), the system has 10 to 20A remaining for other loads. Adding the water heater (25A) exceeds; SMM trips the water heater off.

Step 3: Install SMM at each managed load

Each SMM is wired between the panel breaker and the load. The SMM relay opens to disconnect the load.

Wire each SMM:

• Line side: from the panel breaker
• Load side: to the load
• Control: from the generator controller (24V DC signal typically)
• Power: 120V from the generator's stub feed

The SMM physically fits in or near the panel; check available space.

Step 4: Configure priorities at the controller

At the Generac controller:

• Navigate to the System Management menu
• Set SMM priorities (1 = drop first, 4 = drop last)
• Set the shed threshold (typical 80 to 85 percent of generator capacity)
• Set the resume threshold (typical 65 to 70 percent of generator capacity)

The threshold settings create hysteresis: the SMM doesn't toggle on / off rapidly as load changes.

Step 5: Test the configuration

With the generator running on test:

1. Enable a single managed load (e.g., AC condenser): verify SMM keeps it on
2. Add a second managed load (e.g., water heater): verify SMM either keeps both on or sheds the lower-priority
3. Watch the generator load gauge: should not exceed 85 percent
4. Cycle through customer's typical use patterns
5. Verify shed and resume behavior is acceptable

References

• NFPA 70 (NEC) 2023, Article 702 (Optional Standby Systems).
• NFPA 70 (NEC) 2023, Article 750 (Energy Management Systems).
• NFPA 110 (Standard for Emergency and Standby Power Systems).
• IEEE 446 (Recommended Practice for Emergency and Standby Power for Industrial and Commercial Applications).
• Manufacturer literature: Generac Smart Management Module, Kohler Power Management, Cummins QuietConnect, GE Symphony III.
• Manuall internal: Generator Generator Sizing, Generator Whole House Generator Install, Generator Load Shed and Management.