The module size you need depends on the total number of DIN-rail devices in your installation. Each single-pole MCB occupies 1 module (17.5mm wide); a double-pole device or RCBO occupies 2 modules; a 3-pole MCCB occupies 3 modules. To calculate the required size, count: (1) the main incoming switch (usually 2 modules for a double-pole isolator or MCCB in single-phase, or 3 modules for a 3-pole device in three-phase), (2) all outgoing MCBs and RCBOs (1 or 2 modules each), and (3) any optional devices such as surge protectors (SPDs), timers, or DIN-rail contactors. Add 10–20% spare capacity for future circuit additions. PZ30 sizes available: 6, 10, 14, 18, and 24 modules. As a rough guide: a small studio or one-bedroom apartment typically needs 6–10 modules; a standard 3-bedroom house needs 14–18 modules; a large house or small office with many circuits needs 18–24 modules. Always consult a qualified electrician to determine the exact module count based on your electrical design.

Flush mounting (also called recessed mounting) means the steel box body is embedded into a cavity in the wall, with only the plastic front panel sitting flush with the wall surface. This gives a clean, unobtrusive finish and is the standard choice for new-build installations where wall cavities are accessible during construction. The wall opening must be sized to match the box dimensions. Surface mounting means the entire box is mounted on the surface of the wall, with an optional surface-mount frame or plinth to provide cable access from the rear. Surface mounting is used in retrofit or renovation projects where chasing the wall is impractical, in concrete or solid-wall buildings, or in industrial premises where the box must remain accessible. Both mounting methods provide the same electrical performance; the choice is purely aesthetic and practical. When ordering, specify "flush" or "surface" and, for surface mounting, whether you need the optional surface-mount frame.

The MCB trip curve determines the instantaneous tripping current and should be matched to the load type: (1) Type B — trips between 3 and 5 times the rated current. Suitable for purely resistive loads such as lighting circuits, socket outlets, and general domestic power. This is the most common choice for residential installations. (2) Type C — trips between 5 and 10 times the rated current. Suitable for inductive loads with moderate inrush current such as fluorescent lighting, small motors, and commercial equipment. Type C is commonly used in commercial and industrial installations. (3) Type D — trips between 10 and 20 times the rated current. Suitable for highly inductive loads with high inrush current such as large motors, transformers, and X-ray equipment. Using the wrong trip curve can cause nuisance tripping (if the curve is too sensitive for the load) or delayed protection (if too insensitive). For residential PZ30 boards, Type B is standard for most circuits; Type C may be required for circuits supplying motors or fluorescent lighting banks. Always follow the electrical design and local wiring regulations.

Both approaches provide earth-leakage (residual current) protection and overcurrent protection, but they differ in configuration and module usage: (1) RCBO (Residual Current Circuit Breaker with Overcurrent protection) — a single device that combines RCCB and MCB functions in one unit, occupying 1 or 2 modules per circuit. It provides individual earth-leakage protection for each circuit, meaning a fault on one circuit trips only that circuit, leaving others energized. RCBOs are more expensive per circuit but offer better discrimination and use less wiring. (2) Separate RCCB + MCB — one upstream RCCB (typically 2 modules) protects a group of downstream MCB circuits. This is more cost-effective for multiple circuits but means a fault on any one circuit trips the entire group. Many PZ30 installations use a split-load arrangement: one RCCB protecting the power/socket circuits and another RCCB protecting the lighting circuits, with individual MCBs for each final circuit. For circuits requiring individual protection (e.g., wet areas, outdoor sockets, or critical equipment), an RCBO is preferred. Your electrician should determine the optimal arrangement based on the circuit layout and local regulations.

Yes, the PZ30 can be configured for three-phase (380V/400V) installations. For three-phase, the main incoming switch is a 3-pole or 4-pole MCCB (occupying 3 or 4 modules), and outgoing 3-pole MCBs are used for three-phase loads (e.g., motors, three-phase sockets), while single-pole MCBs distribute each phase to single-phase circuits. The pre-installed N and PE terminal bars provide the required neutral and earth connections for both three-phase and single-phase circuits. For three-phase installations, a larger module size (typically 14 modules or above) is usually required to accommodate the 3-pole main switch and the additional single-pole circuits across three phases. Ensure the main busbar and terminal bars are rated for the three-phase fault current. For higher-current three-phase installations above 100A, consider the XL-21 or GGD cabinet instead of the PZ30, as the PZ30 is limited to 63A/100A main incoming current.

The PZ30 and GHM are both low voltage distribution boxes, but they target different applications: (1) PZ30 — a compact terminal distribution box with a plastic front panel and steel body, designed for final circuit distribution in residential and small commercial premises. It uses DIN-rail mounted MCBs/RCBOs only, has a maximum main current of 100A, 6–24 modules, and is typically flush-mounted into walls. Its primary role is the final consumer unit or fuse board. (2) GHM — a more industrial distribution box available in IP30/IP40/IP54 ratings, supporting up to 630A main busbar and accommodating MCCBs, contactors, relays, and control transformers in addition to MCBs. It is wall-mounted or floor-standing and used for sub-main distribution, small motor control, and commercial/industrial applications where higher currents or control components are needed. In a building's distribution hierarchy, the GHM (or XL-21) acts as a sub-main board feeding multiple PZ30 final distribution boards on each floor or in each apartment. Choose PZ30 for final consumer circuits up to 100A, and GHM for sub-main or light industrial applications up to 630A.