Bosch FLM-420-RLV1-E Relay Interface Module - Low-Volt, LSN, Dual Isolators

Keep your LSN loop running even through wiring faults. The Bosch FLM-420-RLV1-E is a low-voltage relay interface module built into the LSN (Local SecureNet) loop of a security or fire system, allowing devices to switch relays as part of a wider monitored network. Its in-built low current consumption design means it adds minimal load to the overall system it's integrated into.

A key strength of this module is its resilience: two integrated isolators maintain LSN loop functions even if a wire interruption or short-circuit occurs elsewhere on the loop, helping prevent a single fault from taking down the whole system. Switching capacity is rated at up to 5A/30V DC for the DIN rail variant, 1A/30V DC for the in-built variant, and 0.5A/42.4V AC for both variants.

Key features

• In-built, low current consumption relay module
• Two integrated isolators protect LSN loop from faults
• Maintains function through wire interruption or short-circuit
• Switching current up to 5A/30V DC (DIN rail) or 1A/30V DC (in-built)
• 0.5A/42.4V AC switching for both variants

Ideal for

• Bosch LSN-based fire and security systems
• Installers needing fault-tolerant relay switching
• Commercial security and fire alarm installations

Good to know

The module ships complete with a user manual, helping installers correctly wire and configure the relay within the wider LSN loop for reliable, long-term operation.