4 Way Metal Enclosure with 100A Main Switch & 40kA Type 2 Surge Protection

The WMCU440SP is a compact metal surge protection unit combining a 100A main switch with a 2-pole Type 2 SPD rated at 40kA. Designed for installation between the meter and the consumer unit, it provides both safe isolation and surge protection in a single enclosure.

This unit helps bring existing installations in line with the 18th Edition BS 7671 regulations, which require surge protection in most domestic and commercial settings. Built in a durable 4-module steel enclosure, it offers a fast, reliable way to upgrade circuits for compliance and safety.

• Dual protection: 100A main switch plus 40kA Type 2 SPD
• 18th Edition compliant: Suitable for domestic and commercial upgrades
• Compact design: 4-module metal enclosure (130 x 258 x 110mm)
• Pre-assembled: Supplied pre-fitted for quick installation
• Applications: Fits neatly between meter and consumer unit

• Enclosure: 4-module metal, IP-rated steel
• Main Switch: 100A
• Surge Protection Device: Type 2 SPD, 2-pole
• Discharge Capacity: 20kA nominal / 40kA maximum
• Dimensions: 130mm (W) x 258mm (H) x 110mm (D)
• Earthing System: TT, TN-S
• Compliance: BS 7671, 18th Edition
• SKU: WMCU440SP

The WMCU440SP is typically installed between the meter and the main consumer unit, offering isolation and surge protection in one compact housing. Always ensure bonding and SPD earth leads are kept as short as possible to reduce let-through voltage. Installation must be carried out by a qualified electrician in line with 18th Edition regs.

• Pre-assembled for faster installs
• Mount enclosure securely to wall or backboard
• Ensure tails are sized and terminated correctly

What does this unit include?

The WMCU440SP comes with a 100A main switch, 40kA Type 2 SPD, and a 4-module steel enclosure – all pre-assembled for quick installation.

Where should it be installed?

It’s designed to sit between the supply meter and the consumer unit, protecting downstream circuits while providing safe isolation.

Is this 18th Edition compliant?

Yes - it meets the surge protection requirements of BS 7671 (18th Edition) and is suitable for both domestic and commercial applications.

Can I get this in a plastic version?

Yes - Whitecliffe also offers plastic SPD enclosures and alternative sizes. See product WME440SP for the compact metal version.