Surge Arrestor 100kA, 2-4 Pole, 385V | Onesto SPD

The Onesto BY7-100 Surge Protection Device is a Class II (Type 2) surge arrestor rated at 100kA, the highest discharge rating in the Onesto BY7 range. It is designed to protect main electrical incomers, distribution boards and connected equipment from severe transient overvoltage caused by direct or nearby lightning strikes and major switching surges. Suitable for commercial, industrial and high-risk TN and TT power supply networks, it offers a visual pass/fail status indicator so installers and maintenance teams can check protection status at a glance. Available in 2, 3 and 4 pole configurations at 385V, it is the recommended choice for main board protection on sites with significant lightning exposure, such as farms, elevated structures and large commercial premises.

• Application: Suitable for main incoming board surge protection on high-risk TN/TT networks, 385V
• Key specification: 100kA maximum discharge current (Imax), Class II / Type 2 SPD — the highest rating in the Onesto BY7 range
• Configuration: Available in 2, 3 and 4 pole versions
• Status indicator: Green/red indication window shows functional or failed status
• Mounting: 35mm DIN rail, IP20 enclosure

Key Features

• 100kA maximum discharge current (8/20µs) — the highest capacity available in the Onesto BY7 series, suited to severe lightning risk locations
• Visual green (functional) / red (failed) indication window means the device can be checked without removing it from the DIN rail
• PA66 UL94-V0 flame-retardant housing suited to enclosure and distribution board installation
• Compact DIN rail mounting despite the high discharge capacity
• Suitable for TN and TT earthing systems

Typical Applications

• Main incoming board protection for farms, rural properties and elevated structures with severe lightning exposure
• Large commercial and industrial premises requiring maximum surge protection
• First stage of a coordinated (cascaded) surge protection scheme ahead of downstream 10-40kA SPDs
• Protection of critical control, communications and electronic equipment
• Sites with a documented history of lightning-related equipment damage

Technical Specifications

What's Included

• 1 x Onesto BY7-100 Surge Protection Device (pole configuration as selected)

Please note: DIN rail, distribution board wiring, circuit breakers and installation accessories are not included unless specifically listed above.

Installation & Compatibility Notes

• Confirm your board's earthing system (TN or TT) before ordering — this range is supplied at 385V.
• Select the pole configuration (2P, 3P or 4P) that matches your distribution board and phase configuration.
• For sites with severe lightning exposure, consider a coordinated scheme with a downstream 10-40kA SPD closer to sensitive equipment — contact Zisabo for guidance.
• Installation should be carried out by a suitably qualified electrician in line with local wiring regulations.
• Check the status indicator periodically — a red window means the SPD has operated and must be replaced.

Warranty & Support

This product is supplied with the applicable manufacturer or supplier warranty, subject to correct installation, correct application, and warranty terms.

Zisabo supplies quality plumbing, pump, filtration and electrical products with practical support to help customers choose the correct item for their application. If you are unsure whether this product is suitable, contact us before ordering and our team will assist where possible.

Need help choosing? If you are unsure whether this product is suitable for your board, contact Zisabo with your system voltage, earthing type, pole configuration and lightning risk details, and we will assist where possible.