A reliable construction site power connection is the foundation for safe workflows, predictable schedules, and the efficient use of electrically powered equipment. This applies to tower cranes, lighting, containers, and tools as well as to hydraulic power packs that supply concrete demolition shears or stone splitting machines and concrete splitters with hydraulic power. For planning reference, see hydraulic power units for construction. Good planning, appropriate protection, and clean distribution are crucial to deliver power where it is needed—from concrete demolition and building gutting to special demolition and tunnel construction.
Definition: What is meant by construction site power connection
The construction site power connection is the temporary, compliant connection of the construction power supply to the public power grid. This includes a connection point (for example via a site connection box), the main distribution with protection and metering devices, sub-distributions, cables, plug systems, as well as organizational measures for operation, testing, and maintenance. The goal is a safe, adequately sized power supply adapted to the construction phases with three-phase power (typically 400 V) and single-phase AC power (typically 230 V).
Planning and dimensioning of the site power connection
Dimensioning starts with the load profile: Which consumers run simultaneously, what peaks occur, and how do loads change as construction progresses? In addition to continuous loads (lighting, containers), machines with high inrush current—such as hydraulic power packs for concrete demolition shears or stone splitting machines and concrete splitters—primarily determine the connection capacity.
- Determine power demand: rated power, inrush currents, duty cycle, diversity/simultaneity factors.
- Define network type and supply concept: three-phase 400 V for drives, 230 V for small consumers.
- Plan the distribution structure: main distribution, sub-distributions in work zones, short feeders.
- Limit voltage drop: adequate conductor cross-sections and appropriate cable lengths.
- Plan reserves: for phases with higher utilization or additional machines.
Typical connections in practice are CEE 16 A / 400 V, CEE 32 A / 400 V, and CEE 63 A / 400 V for three-phase equipment as well as 230 V outlets for hand tools and measurement technology. Depending on the design, operating powerful hydraulic power packs may require a higher CEE connection, especially if the pack has high inrush currents or multiple packs are operated in parallel.
Connection, distribution, and protection: safety as a system
A construction power system is more than a panel with sockets. Protective measures against electric shock, overload, and short circuit, suitable grounding, and the mechanical protection of cables are integral components. Installation and testing are the responsibility of qualified professionals according to applicable rules and standards for temporary electrical installations.
Site distribution boards and sub-distributions
The main distribution accommodates meters, residual current devices (RCD), and miniature circuit breakers (MCB). Sub-distributions reduce cable lengths to workplaces—such as areas for concrete demolition, building gutting, tunnel heading, or natural stone extraction—and improve selectivity. Enclosures and plug devices require a suitable degree of protection (e.g., against dust and splash water) and robust construction.
RCD, MCB, and selectivity
RCDs serve personal protection and must be matched to the environment and network type. A selective grading of RCDs and MCBs between main and sub-distribution minimizes the consequences of trips: if a downstream protective device trips, other areas remain in operation. For machines with variable-frequency drives or non-linear loads, the suitability of the RCD types must be considered.
Cables, plug systems, and mechanical protection
Flexible, construction-site-rated cables with sufficient cross-section reduce voltage drop and thermal loading. CEE plug systems for three-phase power and robust 230 V sockets must be protected against moisture, dust, and mechanical impacts. Cable crossings must be secured, and cables routed so they are not pinched, run over, or damaged.
Power quality and operating hydraulic power packs
Hydraulic power packs feed concrete demolition shears, stone splitting machines and concrete splitters (rock and concrete splitters), combination shears, or multi cutters. Their performance depends not only on rated voltage and frequency but also on power quality and cable routing.
- Voltage drop: Excessive voltage drop leads to reduced motor performance and increased current draw. Remedies: larger conductor cross-sections, shorter cable runs, sub-distributions close to the work area.
- Inrush current: Motors can require multiples of rated current. Measures include suitable starting methods, adequately sized CEE feeders, and coordinated protection.
- Power factor (cos φ) and harmonics: Non-linear consumers influence RCD selection and cable sizing. The distribution must be designed accordingly.
- Environmental conditions: Dust, moisture, and temperature affect plug connections and heat dissipation. Regular visual and functional checks must be scheduled.
Constantly available 400 V / 50 Hz are important for pressure- and flow-stable hydraulics. Clean power supply enables precise, material-friendly work—for example, when precisely positioning a concrete demolition shear in special demolition or during the fine-structured splitting of natural stone with stone splitting machines.
Alternative supply: generator sets and hybrid solutions
If no grid connection is available, generator sets are used. Apparent power, inrush capability, voltage regulation, and frequency stability are decisive for selection. Especially for hydraulic power packs, it is worthwhile to realistically assess the load profile (start, peaks, continuous operation).
- Generator capacity sized to the highest simultaneous load, including starting reserves.
- Consider the quality of voltage and frequency regulation to protect motors and electronics.
- Hybrid concepts with energy storage can absorb peaks and allow smaller generator sizing.
- Grounding, protective measures, and testing also apply in generator operation.
In noise-sensitive areas—such as gutting works in existing buildings—a grid-supplied, electrically driven solution can offer advantages in emissions and operating comfort. The choice of supply should be aligned with the location, work windows, and machine setup.
Safety and organization
Construction power installations are temporary and change with construction progress. Organization therefore gains importance: clear responsibilities, documented tests, and orderly cable routing.
- Define responsibilities: who plans, who isolates, who tests and documents.
- Regular visual inspections: plugs, couplers, enclosures, interlocks, markings.
- Test intervals according to applicable requirements, especially for changing installation sites.
- Order and labeling: label distributions, assign circuits, keep emergency stop access clear.
- Sub-distributions near workplaces: short paths, reduced tripping and damage risks.
Practical relevance from application areas
Concrete demolition and special demolition
Here, load peaks vary greatly when hydraulic power packs operate concrete demolition shears during concrete demolition and deconstruction in sectional work. Sub-distributions near the deconstruction location and adequately sized CEE feeders reduce voltage drop and ensure constant hydraulic pressure. Selective protection prevents entire construction sections from shutting down when a device trips.
Building gutting and cutting
In existing buildings, noise and exhaust limits are tight. A grid-supplied operation of packs for cutting and shear work is often advantageous. Portable sub-distributions, splash-water-protected sockets, robust extensions, and safe routing across multiple floors without pinch or trip hazards are important.
Rock excavation and tunnel construction
Humid, abrasive environments and long feeders shape the design. Conductor cross-sections must be sized so splitting machines and combination shears at the heading receive sufficient power. Degrees of protection and RCD selection must match the environment, and cables must be mechanically protected.
Natural stone extraction
With longer distances between the main distribution and the extraction face, voltage drop and mechanical stress increase. Mobile sub-distributors near stone splitting machines or multi cutters improve the supply. Regular testing of plug systems is particularly important due to dust and moisture.
Special operations
In special situations—such as constrained inner-city sites or time-critical sections—predefined load scenarios and checklists help. This ensures that the power supply for hydraulic power packs, lighting, and auxiliary technology is time-coordinated and adequately sized.
Checklist for setting up the site power connection
- Record power demand: rated power, inrush current, diversity factor, reserves.
- Select supply concept: grid connection, generator set, or hybrid; three-phase/single-phase.
- Structure the distribution: main distribution, selective sub-distributions, short paths to workplaces.
- Cable sizing: cross-section, length, permissible voltage drop, degree of protection.
- Protective measures: RCD/MCB selection, grounding, mechanical protection, labeling.
- Check power quality: voltage, frequency, starting behavior under load.
- Documentation and testing: commissioning, regular inspections, change management.
Performance requirements of typical consumers on the construction site
The following points support estimating the load profile in conjunction with hydraulic applications:
- Hydraulic power packs for concrete demolition shears and stone splitting machines and concrete splitters: three-phase supply, high inrush currents, varying load due to material resistance.
- Core drilling and concrete cutting: switching between idle and peak load, sensitive to voltage drops.
- Lighting and ventilation: continuous load, relevant for base load and energy demand.
- Containers, heating, charging equipment: base load with diurnal fluctuations.
A load list mapped to specific distribution boards and plug systems creates transparency and facilitates coordination throughout the project duration.
Planning aligned with products and processes
Construction power is not an end in itself. It enables precise, controlled work steps: A concrete demolition shear needs consistent hydraulic pressure to open concrete structures appropriately; stone splitting machines and concrete splitters benefit from defined energy input for reproducible splitting patterns. If the power supply fluctuates, process quality suffers. Planning the power connection is therefore oriented toward the process: Where do peaks occur? Which sections must run in parallel? Where are reserves sensible?
Those who align the electrical supply with the process chain of concrete demolition, building gutting, cutting, and, if applicable, rock excavation or natural stone processing, minimize downtime and reduce technical risks. This applies to day projects as well as long-term deconstruction projects.