Critical and general loads are not yet separated
Life safety, fire protection, security, pumps, cold chain, controls, UPS loads and comfort loads need clear priorities and separate feeder boundaries.
Power-System Component / Protected Load Connection
Low-Voltage Distribution and Critical-Load Segmentation
Starting the generator is only the first step. The distribution system receives power from the generator, ATS or paralleling bus, then protects, meters and directs it to prioritized load circuits so critical equipment returns in the right order.
Incomers and Bus CouplersCritical-Load ZonesFeeder ProtectionExpansion Reserve
Why Distribution Design Matters
To deliver standby power to the correct circuits, define load zones, protection and cable boundaries together
A generator rating does not reveal which circuits start together, which loads must recover first or how a downstream fault should be isolated. Those decisions belong in the distribution design.
A generator, ATS or paralleling system must connect to the existing electrical room
The project needs defined incomers, bus relationships, outgoing feeders, cable routes, protection coordination and service space.
Only total connected kW is available, without circuit loads or starting data
Total kW does not show simultaneity, motor starting or restoration sequence and can lead to nuisance trips or generator overload.
The switchboard is being selected only by rated current
Fault current, breaking capacity, selective protection, busbar withstand and grounding must also match the project and local acceptance requirements.
Complete Route from Source to Load
Generator output becomes a manageable supply only after the incomer, busbar, protection and outgoing feeders work as one chain
Every stage should correspond to the single-line diagram, control sequence and installed equipment. Otherwise adequate generator capacity can still be defeated by unclear interfaces, protection trips or simultaneous load restoration.
Generator, ATS or paralleling bus provides the source
Confirm voltage, frequency, phases, available capacity, grounding method and fault conditions.
Main incomer provides connection and primary protection
The main breaker isolates and protects the board while reporting status to upstream and downstream controls.
Busbar sections and couplers organize sources and zones
Segment the bus around capacity, operating modes and fault boundaries so one fault does not remove every critical load.
Outgoing feeders distribute power to each circuit
Each breaker is selected around equipment current, cable capacity, starting method and protection requirements.
Loads return in prioritized stages
Restore life-safety and control loads first, then add pumps, lifts, chillers and other large loads without creating a second overload.
Status, faults and electrical data remain traceable
Voltage, current, breaker status, alarms and events support routine inspection and fault analysis.
Switchboard and System Configurations
From a single-generator output board to zoned multi-source distribution, configure the lineup around source relationships and load boundaries
Do not start from one standard cabinet. First define the relationship among the generator, ATS, paralleling bus, existing low-voltage system and critical loads.
Generator Incomer and Outgoing Distribution
Connect one generator to a defined set of critical circuits with a main breaker, busbar, metering and feeder protection.
Critical-Load Board Downstream of the ATS
After the ATS selects utility or generator power, distribute standby supply to fire, security, pumps, UPS loads and essential equipment by priority.
Paralleling Bus and Zoned Switchboard Lineup
Manage total capacity, fault isolation and area loads through a common bus, bus couplers and outgoing switchboards.
Integrated Plant-Room or Container Distribution
Combine incomers, control, distribution, cable interfaces and service space for new electrical rooms, outdoor packages and retrofit projects.
High-voltage output requires a separate review of voltage level, transformers, vacuum circuit breakers, relay protection, grounding and local acceptance rules. A low-voltage switchboard design should not be reused as a high-voltage solution.
Load Priorities and Critical Parameters
Define which loads must recover first, then verify eight distribution conditions
Low-voltage distribution is not a simple conversion from generator kW to one main-breaker current. Circuit simultaneity, starting demand, fault conditions, cable length and selective protection must be assessed together.
Tier 1 LoadsLife safety, fire protection, security, emergency lighting, core communications and essential controls.
Tier 2 LoadsCold chain, essential pumps, selected lifts, ventilation and operating auxiliaries that can return in sequence.
Delayable LoadsLarge motors, chillers, compressors and selected production equipment added after the generator stabilizes.
Sheddable LoadsNormal HVAC, landscape systems, noncritical receptacles and comfort loads that may remain off during an emergency.
Voltage, Frequency and PhasesMatch the generator, ATS, transformer and connected equipment
Rated Current and Demand FactorUse maximum simultaneous demand plus realistic expansion reserve
Fault Current and Breaking CapacityDefine breaker, busbar and enclosure withstand requirements
Selective Protection and SettingsClear a fault in the smallest practical circuit area
Busbar Section and Temperature RiseVerify material, joints, supports, clearances and heat dissipation
Cable Size and DistanceInclude ampacity, voltage drop, installation method and starting demand
Cable Entry and Service SpaceReserve terminal, bending, inspection and future-expansion space
Grounding, Neutral and MonitoringDefine the arrangement under the project and local electrical rules
Inside the Switchboard
Distribution reliability depends on verifiable breakers, busbars, protection and wiring
Customers do not need to design the switchboard, but they should be able to verify the main components, circuit labels, service clearances and test records before accepting the system.
Main Incomer Breaker
Connects and isolates the source; rating and breaking capacity must match the system.
Busbars and Bus Couplers
Organize sources and load zones while material, section, support and joints determine temperature rise and fault withstand.
Outgoing Breakers
Protect each feeder according to circuit current, cable capacity and equipment characteristics.
Metering and Status Display
Show voltage, frequency, phase currents, power and breaker positions for operating decisions.
Protection and Control Logic
Responds to overcurrent, earth faults and abnormal voltage and coordinates with ATS and paralleling controls.
Terminals, Wire Numbers and Segregation
Clear terminal blocks, circuit identification and functional separation reduce commissioning and maintenance errors.
Enclosure and Service Space
Strength, ventilation, protection, access and cable-bending space affect long-term maintainability.
Circuit Labels and Test Records
Single-line diagrams, settings, insulation, function and loaded-test results create a traceable handover.
Six Project Inputs
Provide the single-line diagram, circuit loads and site conditions so the switchboard can match the project
Generator, ATS and paralleling data
Provide capacity, voltage, frequency, phases, operating mode, grounding and connection location.
Circuit-by-circuit equipment and priorities
List operating current, starting method, simultaneity and required restoration order for each load.
Existing single line and protection data
Share existing drawings, panel photos, breaker models and settings, and available cable information.
Electrical room, panel location and cable entry
Confirm delivery access, installation dimensions, service clearances, cable trenches, entry direction and environment.
Spare circuits and future capacity
Define planned loads, spare ways, busbar margin, terminals and phased-implementation boundaries.
Protection, functional and loaded testing
Define insulation, phase sequence, interlocks, protection, circuit verification and load-restoration test methods.
Typical Distribution Tasks
Critical loads differ by facility, so zoning and restoration sequences must be defined for each project
Place life safety, UPS and cooling auxiliaries on clearly identified critical buses
Separate no-break loads, UPS-backed loads and staged-restoration equipment while keeping faults locally isolatable.
Separate fire, common-area, tenant and comfort loads
Restore fire protection, security, emergency lighting, essential lifts and pumps first, then add other circuits within generator capacity.
Restore PLC and process protection before large motors
Organize controls, cooling, drainage, compressed air and production loads in the process sequence to reduce voltage dips and trips.
Review the low-voltage distribution concept around the single-line diagram, critical loads and site conditions
Share source capacity, circuit loads and priorities, existing drawings, breaker and cable data, room dimensions, cable-entry direction and expansion plans. HOHANK engineers will define the switchboard lineup, protection, busbars, cabling and test scope.