What Is a Service Protection Device?
A plain-language explanation of service protection devices — what SPD and MPD service fuses do, their ratings and why they are sealed by the network.
The service fuse
A service protection device is the fuse that protects the service line and metering installation, sitting between the point of attachment and the meter. SPD (single phase) and MPD (multi phase) enclosed fuse units are the standard formats — sealable, insulated and rated for the service capacity.
SPD or MPD, 80A or 100A
The format follows the phase configuration and the rating follows the network's requirements for the service capacity.
| Device | Phases | Common ratings |
|---|---|---|
| SPD | Single phase | 80A / 100A |
| MPD | Multi / three phase | 80A / 100A per phase |
Sealed by the network
Service fuses are network-sealed equipment. Enclosed units with proper sealing provisions keep the installation compliant and avoid the defect notices that come from open or non-standard fuse holders. EVO stocks SPD and MPD units for the trade — request a quote with your service details.
Frequently Asked Questions
What is the difference between an SPD and an MPD?
An SPD is a single-phase service protection device and an MPD is a multi-phase (three-phase) one. Both are sealable, insulated, enclosed fuse units rated for the service capacity, commonly 80A or 100A per phase.
Should a service fuse be 80A or 100A?
The rating follows the network's requirements for the service capacity, not the installation's maximum demand alone. Standard residential services typically run 80A per phase; upgraded services step to 100A. Always confirm against the local service rules.
Related Products
Meter Panels
AS 1795 insulated bakelite panels, cut to order
Electrical Meter Boxes
Galvanised meter boxes from 300x300 to 600x900
Level 2 Metering Equipment
Gear for Level 2 ASP metering and service work
Current Limiters
Service current limiting for compliant connections
Meter Boxes
Galvanised steel meter boxes
Switchboards
Main switchboards & distribution boards
Meter Surrounds
Panels & surrounds for meter installations
Real Estate & Insurance Repairs
Like-for-like replacements after damage or defect reports
Level 2 ASP Contractors
Disconnect/reconnect, metering and overhead service work
Keep Reading
Service Fuses Explained: SPD and MPD
What SPD and MPD service protection devices do, when 80A or 100A is the right rating, and where they sit in the metering installation.
Neutral Links: Consumer vs Service, and Why Sealable Matters
What a neutral link does, the difference between consumer and service neutral links, and why hole count and sealability matter when ordering.
Solar Metering: What Changes at the Meter Box
Bidirectional metering, main switch requirements and panel space — what a solar installation needs at the metering position.