Cut-Out (Service Head)

What is a Cut-Out?

The cut-out, also known as the service head or main fuse, is the termination point of the Distribution Network Operator's (DNO) electricity supply cable. It marks the boundary between DNO-owned equipment and the customer's electrical installation.

Cut-Out Components

A typical cut-out contains:

• Service fuse - Main protective device (usually 60A, 80A, or 100A)
• Neutral link - Connection for neutral conductor
• Terminal connections - For meter tails
• Sealed enclosure - DNO security seal

Why Cut-Outs Matter for Installers

For renewable energy installations, the cut-out is significant because:

• Isolation point - Where supply is disconnected for safe working
• Capacity check - Fuse rating affects system sizing
• Upgrade requirement - May need upgrading for larger systems
• Access restrictions - Traditionally DNO-only access

SIP and Cut-Out Access

Without SIP accreditation, only DNO personnel can:

• Remove the service fuse
• Break the DNO seal
• Re-seal after work completion

With SIP accreditation, your engineers can perform these operations, eliminating DNO waiting times.

Cut-Out Safety

Working at the cut-out requires:

• Appropriate PPE and tools
• Competence in isolation procedures
• Understanding of supply arrangements
• Knowledge of re-energisation protocols

This is why SIP accreditation includes rigorous safety training.

Common Cut-Out Issues

• Aged equipment requiring replacement
• Inadequate fuse rating for new loads
• Access difficulties in meter cupboards
• PME (TN-C-S) earthing considerations